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Lyčka, Lukáš. "Punching Shear of Flat Slabs." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-408019.
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The use of flat slabs in constructions due to its many functional and economic advantages is wide-spread. Behavior of flat slabs in shear and flexure is a fairly complex problem. Therefore, the punching shear failure belongs to one of the most critical aspects in the design of concrete buildings. Over the last decades several buildings have collapsed due to the failure of the punching shear strength, resulting in loss of lives and financial damages. These disasters revealed gaps in the current (or former) design codes and recommendations. As a part of theoretical framework of the dissertation a method for predicting the punching shear strength of flat slabs was developed. Several experiments on scaled down slabs were conducted in order to verify the proposed method and for optimization of its parameters. Proposed method in development predicts the punching shear for slabs without shear reinforcement according to the EC2 and replaces the area of the shear crack with a system of struts and ties.
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Shao, Xiao-yun. "Punching shear strength of reinforced concrete slab." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/10727.
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This thesis presents the results of punching shear tests performed on a 2 x 2 bay continuous slab with/and without supplementary supports. On the basis of these tests, the code method of calculating the ultimate strength of interior, edge and corner column connections of flat slab were investigated. The thickness of the specimen was 140 mm and the spans length were 2743 mm. The ACI 318-89, BS 8110-85 and CEB-FIP 90 Codes were critically reviewed by comparing with the experiment results and results from the literature. It was found that in general the Code predictions are reasonable but for corner column connections the ACI Code over-estimates the ultimate shear capacity of the slab and BS 8110-85 requirements for edge and corner column connections are simplistic. The experimental results show that the supplementary supports can increase the ultimate punching shear capacity when the supports are properly located.
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Habibi, Farshad. "Post-punching shear response of two-way slabs." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110632.
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This thesis investigates the post-punching behaviour of reinforced concrete slab-column connections. Seven interior slab-column connections were tested to study the effects of slab thickness, the length of structural integrity reinforcing bars, the distribution of structural integrity reinforcement in slabs with rectangular columns and the placement of structural integrity reinforcement in slabs with drop panels. Results from this test series and from tests by other researchers were compared with predictions using the CSA A23.3-04 design equations for both punching shear and post-punching resistance. The test results demonstrated that the provision of structural integrity reinforcement in accordance with the requirements of CSA A23.3-04 resulted in significant post-punching resistance and the design equations provide a reasonable estimate of this resistance. In addition, an analytical model for predicting the post-punching shear response of slab-column connections is presented which accounts for the individual contributions of each layer of top reinforcement and each layer of the structural integrity reinforcement. The contribution of each layer of top and integrity reinforcement is governed by three different failure modes, including rupture of the bars, concrete breakout of the bars and pullout of the bars. The predictions are compared with experimental results and the results obtained by the CSA A23.3 Standard design method. There was a good agreement between the predicted results and the experimental results.Cette thèse examine le comportement après poinçonnement des raccords dalle-colonne en béton armé dans le but de fournir le renforcement adéquat pour assurer l'intégrité structurale. Les résultats d'essais sur sept raccords dalle-colonne intérieurs sont présentés. L'étude portait sur les effets de l'épaisseur de la dalle, de la longueur des barres d'armature pour l'intégrité structurale, de la distribution de l'armature d'intégrité structurale dans les dalles avec colonnes rectangulaires et sur le placement de l'armature d'intégrité structurale dans les dalles avec des goussets. Les résultats de cette série d'essai et ceux d'autres chercheurs ont été comparés aux prévisions des équations de calcul de la norme CSA A23.3-04 pour le cisaillement par poinçonnement et la résistance après poinçonnement. Les résultats des essais montrent que la clause d'armature d'intégrité structurale selon les exigences de la norme CSA A23.3-04 produit une résistance importante après poinçonnement; les équations de calcul ont également fourni une estimation raisonnable de cette résistance. De plus, un modèle analytique permettant de prédire la réponse post-poinçonnement des connexions dalle-poteau est présenté. Ce modèle tient compte de la contribution de chaque lit d'armatures supérieures et chaque lit d'armature d'intégrité structurale. Cette contribution des deux lits d'armature est dictée par trois modes de rupture : rupture des armatures, rupture tronconique du béton et rupture par défaut d'ancrage des armatures. Les prédictions du modèle sont comparées aux résultats expérimentaux et aux résultats obtenus à l'aide de la méthode de dimensionnement de la norme CSA. La corrélation entre les prédictions de la méthode et les résultats expérimentaux est excellente.
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Kennedy, Brian Wayne. "Punching shear of high-strength concrete slabs with perforations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq21178.pdf.
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Xiang, Zhen Xian. "Punching shear strength of waffle slabs at internal columns." Thesis, University of Leeds, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367299.
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Harris, Devin K. "Characterization of Punching Shear Capacity of Thin Uhpc Plates." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/36366.
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UHPC (ultra-high performance concrete) is a relatively new type of concrete that exhibits mechanical properties that are far superior to those of conventional concrete and in some cases rival those of steel. The main characteristics that distinguish UHPC from conventional reinforced concrete are the improved compressive strength, the tensile strength, the addition of steel fibers, and the resistance to corrosion and degradation. The mechanical properties of UHPC allow for smaller, thinner, lighter sections to be designed while strength is maintained or improved. The use of UHPC has been limited to a few structural applications due to the high cost of the materials and the lack of established design guidelines.
A proposed material model based on material and finite element models has served as the foundation of this research effort. The model was used to minimize the dimension of an optimum section in order to limit the material usage and maximize the performance. In the model, the top flange served as the riding surface and contained no reinforcing steel to resist shear. The lack of steel reinforcement allowed for the possibility of a punching shear failure to occur from the application of a point load such as a wheel tire patch load. The model and optimized section served as the foundation for this research, the characterization of punching shear capacity of thin UHPC plates.
A total of 12 UHPC slabs were tested to failure to determine the boundary between a flexural failure and a punching shear failure. The variables considered were the slab thickness and loading plate dimensions. The results of the testing were compared to existing models for punching shears and other failure modes, with varying success. The test results aided in the development of a design equation for the prediction of punching shear in UHPC slabs. After evaluation of the test results, recommendations are made as to which model predicts the punching shear capacity of UHPC slabs and the minimum slab thickness required to prevent a punching shear failure.Master of Science
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Aalto, Jonatan, and Elisabeth Neuman. "Comparison of Punching Shear Design Provisions for Flat Slabs." Thesis, KTH, Betongbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215631.
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Abstract A new generation of EN 1992-1-1 (2004) also known as Eurocode 2 is under development and currently there is a set of proposed provisions regarding section 6.4 about punching shear, PT1prEN 1992-1-1(2017). It was of interest to compare the proposal with the current punching shear design provisions. The aim of this master thesis was to compare the punching shear resistance obtained in accordance with both design codes. Furthermore the eect of some parameters on the resistance was to be compared. It was also of interest to evaluate the userfriendliness of the proposal. In order to meet the aim, a case study of a real at slab with drop panels was performed together with a parametric study of a pure ctive at slab. The parametric study was performed for inner, edge and corner columns in the cases prestressed, without and with shear reinforcement. It was concluded that the distance av from the column axis to the contra exural location has a big in uence on the punching shear resistance. The factor ddg considering concrete type and aggregate properties also has a big impact on the resistance. The simplied estimation of av according to 6.4.3(2) in PT1prEN 1992-1-1 (2017) may be inaccurate in some cases. The length b0 of the control perimeter has a larger eect on the resistance in EN 1992-1-1 (2004) than in PT1prEN 1992-1-1 (2017). In PT1prEN 1992-1-1 (2017), studs located outside the second row has no impact on the resistance. The tensioning force in a prestressed at slab has a larger in uence on the resistance in PT1prEN 1992-1-1 (2017) than in EN 1992-1-1 (2004). Furthermore, the reinforcement ratio is increased by the tendons, and thus aect the resistance in PT1prEN 1992-1-1 (2017). Clearer provisions for the denition of the support strip bs for corners and ends of walls are needed in PT1prEN 1992-1-1 (2017). It may be questionable if the reduction of the perimeter for a large supported area in accordance with 6.4.2(4) in PT1prEN 1992-1-1 (2017) underestimates the resistance v in some cases. Considering the work-load with PT1prEN 1992-1-1 (2017), more parameters are included. However, they may not require that much eort to obtain. Keywords: Punching shear, resistance, concrete, at slab, design provisions, Eurocode 2, case study, parametric study, shear reinforcement, prestressed vi
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Tazaly, Zeinab. "Punching Shear Capacity of Fibre Reinforced Concrete Slabs with Conventional Reinforcement : Computational analysis of punching models." Thesis, KTH, Bro- och stålbyggnad, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118825.
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Steel fibre reinforced concrete is not a novel concept, it has been around since the mid-1900s, but despite its great success in shotcrete-reinforced rock walls and industrial floors it has not made any impact on either beams or elevated slab. Apparently, the absence of standards is the main reason. However, the combination of steel fibre reinforced concrete and conventional reinforcement has in many researches shown to emphasize good bearing capacrty. In this thesis, two punching shear capacity models have been analysed and adapted on 136 test slabs perfomred by previous researchers. The first punching model altemative is proposed in DAfStB - BetonKalender 201l, and the second punching model alternative is established in Swedish Concrete Association - Report No. 4 1994. Due to missing information of the experimental measured residual tensile strength, a theoretical residual tensile strength was estimated in two different manners to be able to adapt the DAfStB punching model altemative on the refereed test slabs. The first solution is an derivation of a suggestion made by Silfiverbrand (2000) and the second solution is drawn from a proposal made by Choi etal. (2007). The result indicates that the SCA punching model alternative is easier to adapt and provides the most representative result. Also DAfStb altemative with the second solution of estimating the residual strength contributes to arbitrary result, however due to the uncertainty of the estimation of the residual tensile strength, the SCA punching model is recommended to be applied until further investigation can confirm the accuracy of the DAfStB alternative with experimentally obtained residual tensile strength.
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Li, Kevin Ka Lun 1975. "Influence of size on punching shear strength of concrete slabs." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30259.
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The punching shear behaviour of interior slab-column connections in flat plates is investigated. The response of six two-way slab specimens, which were designed such that they would fail in punching shear, are presented. The parameter introduced in the experimental program is member depth. The effects of this parameter on the punching shear capacity of slab elements are investigated. The results show a strong "size effect", with deeper members having a smaller shear stresses at failure than shallow ones.Test results obtained from this experimental program are compared with the punching shear predictions of the Canadian CSA A23.3-94 Standard, the American ACI 318-95 Code, the British BS 8110-85 Standard and the European CEB-FIP 1990 Model Code. Predictions were also made using computer program "Response 2000", assuming an equivalent beam analogy to represent the slab. It is concluded that the shear design of slabs, according to the current Canadian and American codes, can be unconservative under certain conditions, particularity for thick slabs. It is recommended that the punching shear expressions of the CSA Standard and the ACI Code be modified to take into account the "size effect" on the punching shear strength of slabs.
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Li, Kevin Ka Lun. "Influence of size on punching shear strength of concrete slabs." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0033/MQ64235.pdf.
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Hussein, Ahmad Fikri. "Punching shear strength at edge columns in ribbed flat slabs." Thesis, University of Leeds, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367699.
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Gomes, Ronaldo Barros. "Punching resistance of reinforced concrete flat slabs with shear reinforcement." Thesis, University of Westminster, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303158.
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Diangha, Maurice Nkinyam Boh. "Punching shear modes of failure in impacted reinforced concrete beams." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245559.
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Kuang, Jun Shang. "Punching shear failure of concrete slabs with compressive membrane action." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240241.
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Smith, Holly Kate Mcleod. "Punching shear of flat reinforced-concrete slabs under fire conditions." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20962.
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This thesis examines punching shear response of reinforced-concrete flat slabs under fire conditions. The shear behaviour of concrete in fire is relatively poorly understood compared to its flexural response. Failures such as the Gretzenbach car park failure in Switzerland (2004) have prompted concerns over the punching shear capacity of flat slabs in fire. The shear behaviour of reinforced-concrete in fire depends on degradation of the individual material properties with temperature, their interaction, and more recently recognised, the effects of restrained thermal expansion. Through experimental testing this thesis aims to build a foundation understanding of the punching shear behaviour of flat reinforced-concrete slabs in fire conditions. A series of shear blocks, tested after exposure to elevated temperature (realistic fire temperature), were used to develop an understanding of the effects of elevated temperature on the shear transfer performance of reinforced-concrete. These tests allowed the complex interplay of shear-carrying mechanisms at ambient temperature to be extended to the case of post-elevated temperature. Fifteen slab-column punching shear specimens were tested under both applied load and extreme heating. In particular, the effects of restrained thermal expansion were experimentally investigated by altering the support conditions of the slab-column specimens. A purpose-built restraint frame allowed the boundary support conditions to be either fully restrained or unrestrained. This experimental series is the only series to have tested restrained specimens at elevated temperatures, though previous researchers have simulated the thermal restraint effects and reported the importance of restrained thermal expansion and curvature on the behaviour of punching shear. Parameters of slab thickness and reinforcement ratio were also varied to investigate their respective impacts on punching shear behaviour at elevated temperature. The thicker 100 mm reinforced slabs failed in punching shear, whereas the 50 mm and 75 mm thick slabs failed in flexure-shear mechanisms and the unreinforced slabs failed in flexure. Clear behavioural differences were observed between specimens with different support conditions. Unrestrained 100 mm thick slabs under sustained load failed soon after heating began, whereas none of the corresponding restrained specimens failed during heating. One restrained, heavily reinforced specimen failed during cooling, whilst under sustained load. This is the first recorded punching shear failure during the cooling phase of an elevated temperature test and may also be the first recorded test specimen ever to have failed during the cooling phase of an elevated temperature test. This failure highlights the unknown and potentially unsafe behaviour of structures during the cooling phase. Further structural investigation of the cooling behaviour of concrete flat slabs after exposure to fire, needs to be undertaken. Most of the specimens’ central deflection was away from the heat source (in the direction of loading) during the whole test, irrespective of support condition. The test setup was assessed to investigate the unusual slab-column deflection away from the heat source, however the complex behaviour observed during the tests cannot currently be explained. It is assumed that the degradation in concrete properties and non-linear material behaviour dominates over the thermal expansion of the slabs. Quantitative and qualitative comparisons are presented, though the quantitative data is impacted by size effect, non-repeatable heating application between tests and jack friction influences on specimens with low capacities. Eurocode 2 punching shear prescriptive elevated temperature design, extends the ambient temperature equation for elevated temperature use, by degrading the temperature-dependant parameters by factors. Support conditions are not considered, with the code specifically telling the designer not to consider in-plane thermal expansion effects, therefore consequently ignoring the premature punching shear failure that can occur. Furthermore, the ambient temperature equation is based on the regression of available experimental data at the time and does not consider the reinforcement as a shear transfer mechanism. The experimental capacities of the 100 mm thick, reinforced slabs that failed in pure punching shear mechanism were similar to the Eurocode 2 punching shear prescriptive design capacity, when directly compared. The unrestrained support condition was shown to be consistently, not conservatively predicted by Eurocode 2, whereas the restrained support condition capacities were conservatively predicted. It is comforting to know that the Eurocode 2 design predicts the restrained supported slabs conservatively, as real buildings are more likely to have supports closer to the restrained condition rather than the unrestrained support condition. A sensitivity analysis of the Eurocode 2 prescriptive design equation shows it is highly sensitive to the concrete strength degradation and not the variable, cp, which was used to make a support condition comparison in this thesis. This indicates how the Eurocode 2 equation for punching shear capacity lacks in its consideration of whole structural behaviour. The Critical Shear Crack Theory has been proposed as the background to a harmonised shear design approach, called Model Code 2010. The Critical Shear Crack Theory was safe in predicting the experimental punching shear capacities. There were large variances for the 100 mm thick slabs, however they are consistent with the original model comparison to test data. An expansion of the Critical Shear Crack Theory for elevated temperature requires further validation with experimental restrained thermal expansion tests, such as those presented in this thesis. Finally, a digital image correlation technique has been proven to be a reliable method to measure structural displacements of concrete at elevated temperatures. Digital image correlation allowed the crack locations and slab rotation angles to be visualized throughout testing. No other measurement techniques are able to provide similar versatility in fire testing such as that presented herein.
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Salim, Wijaya. "Punching shear failure in reinforced concrete slabs with membrane restraint." Thesis, University of Bristol, 2006. http://hdl.handle.net/1983/e2a8f32a-0fc2-40ee-8183-a9100122e429.
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Kamaraldin, Khaled. "Punching shear and moment transfer in reinforced concrete flat slabs." Thesis, University of Westminster, 1990. https://westminsterresearch.westminster.ac.uk/item/94vwq/punching-shear-and-moment-transfer-in-reinforced-concrete-flat-slabs.
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Thuresson, Sofia. "Parametric optimization of reinforced concrete slabs subjected to punching shear." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279466.
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The construction industry is currently developing and evolving towards more automated and optimized processes in the project design phase. One reason for this development is that computational power is becoming a more precise and accessible tool and its applications are multiplying daily. Complex structural engineering problems are typically time-consuming with large scale calculations, resulting in a limited number of evaluated solutions. Quality solutions are based on engineering experience, assumptions and previous knowledge of the subject.The use of parametric design within a structural design problem is a way of coping with complex solutions. Its methodology strips down each problem to basic solvable parameters, allowing the structure to be controlled and recombined to achieve an optimal solution.This thesis introduces the concept of parametric design and optimization in structural engineering practice, explaining how the software application works and presenting a case study carried out to evaluate the result. In this thesis a parametric model was built using the Dynamo software to handle a design process involving a common structural engineering problem. The structural problem investigated is a reinforced concrete slab supported by a centre column that is exposed to punching shear failure. The results provided are used for comparisons and as indicators of whether a more effective and better design has been achieved. Such indicators included less materials and therefore less financial cost and/or fewer environmental impacts, while maintaining the structural strength. A parametric model allows the user to easily modify and adapt any type of structure modification, making it the perfect tool to apply to an optimization process.The purpose of this thesis was to find a more effective way to solve a complex problem and to increase the number of solutions and evaluations of the problem compared to a more conventional method. The focus was to develop a parametric model of a reinforced concrete slab subjected to punching shear, which would be able to implement optimization in terms of time spent on the project and therefore also the cost of the structure and environmental impact.The result of this case study suggests a great potential for cost savings. The created parametric model proved in its current state to be a useful and helpful tool for the designer of reinforced concrete slab subjected to punching shear. The result showed several solutions that meet both the economical and the punching shear failure goals and which were optimized using the parametrical model. Many solutions were provided and evaluated beyond what could have been done in a project using a conventional method. For a structure of this type, a parametric strategy will help the engineer to achieve more optimal solutions.Just nu utvecklas Byggbranschen mot mer automatiserade och optimerade processer i projektdesignfasen. Denna utveckling beror till stor del på teknikutveckling i form av bättre datorprogram och tillgänglighet för dessa. Traditionellt sett löses komplexa konstruktionsproblem med hjälp av tidskrävande och storskaliga beräkningar, vilka sedan resulterar i ett begränsat antal utvärderade lösningar. Kvalitets lösningar bygger då på teknisk erfarenhet, antaganden och tidigare kunskaper inom ämnet.Användning av parametrisk design inom ett konstruktionsproblem är ett sätt att hantera komplexa lösningar. Dess metod avgränsar varje problem ner till ett antal lösbara parametrar, vilket gör att strukturen kan kontrolleras och rekombineras för att uppnå en optimal lösning.Denna avhandling introducerar begreppet parametrisk design och optimering i konstruktionsteknik, den förklarar hur programvaran fungerar och presenterar en fallstudie som genomförts för att utvärdera resultatet. I denna avhandling byggdes en parametrisk modell med hjälp av programvaran Dynamo för att hantera en designprocess av ett vanligt konstruktionsproblem. Det strukturella problemet som undersökts är en armerad betongplatta som stöds av en mittpelare, utsatt för genomstansning. Resultaten används för att utvärdera om en bättre design med avseende på materialanvändning har uppnåtts. Minimering av materialanvändning anses vara en bra parameter att undersöka eftersom det ger lägre kostnader och/eller lägre miljöpåverkan, detta undersöks under förutsättning att konstruktionens hållfasthet bibehålls. En parametrisk modell gör det möjligt för användaren att enkelt modifiera en konstruktionslösning med avseende på olika parametrar. Detta gör det till det perfekta verktyget att tillämpa en optimeringsprocess på.Syftet med denna avhandling var att hitta ett mer effektivt sätt att lösa ett komplext problem och att multiplicera antalet lösningar och utvärderingar av problemet jämfört med en mer konventionell metod. Fokus var att utveckla en parametrisk modell av en armerad betongplatta utsatt för genomstansning, som kommer att kunna genomföra optimering med avseende på tid som spenderas på projektet och därmed också kostnaden för konstruktionen och miljöpåverkan.Resultatet av denna fallstudie tyder på att det finns en stor möjlighet till kostnadsbesparingar och anses därför vara ett mycket hjälpsamt verktyg för en konstruktör. Resultatet visade flera lösningar som uppfyllde de konstruktionsmässiga kraven samtidigt som de gav en lägre materialanvändning tack vare optimeringen. Många lösningar tillhandahölls och utvärderades utöver vad som kunde ha gjorts i ett projekt med en konventionell metod. En parametrisk strategi kommer att hjälpa ingenjören att optimera lösningen för en konstruktion av denna typ.
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Kallage, Mahmoud Rezai. "Punching shear strength of continuous post-tensioned concrete flat plate." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6605.
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A two bay by two bay continuous, unbonded post-tensioned flat plate was constructed and loaded to failure. The slab was designed in accordance with the provisions of ACI 319-89 except that no supplementary bonded reinforcing steel was provided. The prestressing tendons were uniformly distributed in one direction and banded in span/6 column strips in the other direction. In both directions the average prestress on the concrete was 3.5 MPa. The dimensions of each bay were 2.75 m, the slab thickness was 89 mm, mean concrete cylinder strength was 44 MPa. The load was applied monotonically until punching shear occurred at an edge column on the side parallel to banded tendons. The failed column was shored and the slab reloaded until punching shear occurred at the interior column. The lack of supplementary bonded reinforcing steel in regions of moment transfer had no apparent detrimental effects so it must be concluded that the prestress was effective right to the edge of the concrete. The use of 100% banded tendons in one direction and uniform distribution in the other direction had no adverse effects on either the flexural or punching shear behaviour. The literature was reviewed to locate experimental results of punching shear tests for isolated prestressed concrete flat plates, continuous prestressed flat plate systems and tests of flat plate column connections under shear and moment transfer. The strength capacities calculated using the provisions of ACI 318-89, CSA A23.3-84M, BS8110-85 and the CEB Model Code 1990 were compared to the test results and those from the literature review.
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Megally, Sami Hanna. "Punching shear resistance of concrete slabs to gravity and earthquake forces." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0008/NQ34686.pdf.
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Sha'at, Emad. "Punching shear strength of reinforced concrete flat slabs at edge columns." Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261880.
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Abdullah, Ahmad Mahmoud. "Analysis of repaired/strengthened R.C. structures using composite materials : punching shear." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/analysis-of-repairedstrengthened-rc-structures-using-composite-materials-punching-shear(6fd3f27c-ef35-4996-9707-09187ad10e9f).html.
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Fibre reinforced plastics (FRP) have been used widely in civil engineering in order to improve the structural response (deformation and stress). Most of the current codes for the strengthening of RC structures do not provide enough provision for the design of the column-slab connections strengthened with externally bonded reinforcement (EBR) due to the lack of research covering this area. This study is to investigate, both experimentally and analytically, the effectiveness of bonding pre-stressed carbon fibre plates to the tension surface of concrete column-slab connections in both the serviceability and ultimate limit state. The experimental programme comprises five full-scale specimens that are designed and fabricated to simulate an interior column-slab connection. The prestressing technique, application procedure and prestressing device are described in detail in this study. Different prestressing forces are applied to the FRP plates bonded to the concrete substrate. The structural response of the strengthened specimens are compared with a reference specimen in terms of punching shear strength, deflection profile, strain, crack opening displacement and failure modes. Furthermore, a finite element model using ABAQUS is built to obtain a further insight into the punching behaviour of the test slabs. Both experimental and numerical results are compared, and a parametric study on the effect of the FRP-concrete interface on the structural integrity is conducted. Results are also compared with Eurocode 2 and ACI for the prediction of the punching strength. It was found that bonding of prestressed FRP plates to the tensile face of the concrete slabs improved the serviceability, but was not able to enhance the ultimate behaviour as much as the non-prestressed FRP plates. The development of the critical diagonal crack (CDC) was the main reason for diminishing the ultimate strength of the strengthened slabs.
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Zamani, Zavieh Shahram. "Punching shear strength of edge column connections of rectangular flat plates." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26550.
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Edge column slab connections of continuous flat plate structures, under combined shear and moment transfer, can be susceptible to failure by punching shear. A 2 bay by 2 bay, rectangular flat plate, panel aspect ratio 2:1, was fabricated and loaded to failure under a simulated uniformly distributed load. The edge and corner columns were supported so that the reactions and reactive moments could be measured. The interior column, no moment transfer, punching shear strength was less than inferred from previous research. Based upon the strain gauge results neither the long or short direction flexural reinforcements yielded. The fact that the interior column was rectangular in section was a complication.
Comparison of the measured reactions to those calculated by finite element analysis, FEM, and a modified direct design method, RDDM shows that both methods predict the reactions with acceptable accuracy. (Abstract shortened by UMI.)
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Al-Quraishi, Hussein Abbas Azeez [Verfasser]. "Punching Shear Behavior of UHPC Flat Slabs / Hussein Abbas Azeez Al-Quraishi." Kassel : Universitätsbibliothek Kassel, 2014. http://d-nb.info/1060472589/34.
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Fong, Dickson Wen Jing. "Punching shear in waffle slabs in the presence of biaxial moment transfer." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/51640/.
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An extensive amount of works have been carried out to develop the current understanding in punching shear mechanism noted in reinforced concrete slabs. However, despite the increasing popularity of waffle slabs, the current understanding about punching behaviour is mainly focused on solid flat slabs, and only limited amount of works have been carried out on waffle slabs and in the presence of biaxial moment. Thus, there is a need to carry out a research in this area to aid the understanding about punching mechanism of waffle slabs in the presence of biaxial moment for the internal column and edge column connections. The experimental work carried out in this research included destructive testing of thirty-eight 1/10th scale model waffle slab specimens, which consists of fifteen internal column slabs and twenty-three edge column slabs. The main variables were, for the internal column slab, the principle angles of biaxial moment transfer, the column eccentricity, the column orientation and the size of solid sections, and for the edge column slab, the principle angles of biaxial moment transfer, the column eccentricity, the column location and the size of solid sections. From the experimental investigations, three distinct failure mechanisms were observed: the concentric punching at internal column mechanism; the eccentric punching at internal column mechanism; and the edge punching mechanism. In general, the observed punching shear failure mechanisms of waffle slabs were found identical to solid flat slabs; but the punching shear capacities reduced due to some losses in potential failure surface within the waffle section. The principle angle of biaxial moment transfer was found varying the shear surface area that was being mobilized, thus affecting the punching capacity of the slabs. An analytical study was carried out, using an upper-bound plastic model, to simulate the observed punching shear mechanisms, and hence, to predict the punching capacity of the slabs. A theoretical model was developed for each of the identified failure mechanism. In addition, three design models based on the current UK code, Eurocode 2, have been developed. In all cases, these models have achieved good agreements with the test results.
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Al, Ajami Abdulhamid. "Punching shear of concrete flat slabs reinforced with fibre reinforced polymer bars." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/16864.
Full textAbstract:
Fibre reinforcement polymers (FRP) are non-corrodible materials used instead of
conventional steel and have been approved to be an effective way to overcome
corrosion problems. FRP, in most cases, can have a higher tensile strength, but
a lower tensile modulus of elasticity compared to that of conventional steel bars.
This study aimed to examine flat slab specimens reinforced with glass fibre
reinforced polymer (GFRP) and steel bar materials for punching shear behaviour.
Six full-scale two-way slab specimens were constructed and tested under
concentric load up to failure. One of the main objectives is to study the effect of
reinforcement spacing with the same reinforcement ratio on the punching shear
strength. In addition, two other parameters were considered, namely, slab depth,
and compressive strength of concrete.
The punching shear provisions of two code of practises CSA S806 (Canadian
Standards 2012) and JSCE (JSCE et al. 1997) reasonably predicted the load
capacity of GFRP reinforced concrete flat slab, whereas, ACI 440 (ACI
Committee 440 2015) showed very conservative load capacity prediction.
On the other hand, a dynamic explicit solver in nonlinear finite element (FE)
modelling is used to analyse a connection of column to concrete flat slabs
reinforced with GFRP bars in terms of ultimate punching load. All FE modelling was performed in 3D with the appropriate adoption of element size and mesh.
The numerical and experimental results were compared in order to evaluate the
developed FE, aiming to predict the behaviour of punching shear in the concrete
flat slab. In addition, a parametric study was created to explore the behaviour of
GFRP reinforced concrete flat slab with three parameters, namely, concrete
strength, shear load perimeter to effective depth ratio, and, flexural reinforcement
ratio. It was concluded that the developed models could accurately capture the
behaviour of GFRP reinforced concrete flat slabs subjected to a concentrated
load.
Artificial Neural Networks (ANN) is used in this research to predict punching
shear strength, and the results were shown to match more closely with the
experimental results. A parametric study was performed to investigate the effects
of five parameters on punching shear capacity of GFRP reinforced concrete flat
slab. The parametric investigation revealed that the effective depth has the most
substantial impact on the load carrying capacity of the punching shear followed
by reinforcement ratio, column perimeter, the compressive strength of the
concrete, and, the elastic modulus of the reinforcement.
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Jalal, Pasha, and Jose Andres Perez. "Punching shear in concrete flat slabs supported on slender edge steel columns." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278546.
Full textAbstract:
Punching shear is a failure mechanism caused by concentrated loads, creating a crack pattern that resembles a cone shape or piece of pie starting from the top surface of the slab and prolongs downwards. When the total shear force is greater than the shear resistance of the slab, it may eventually lead to punching shear failure. It can be visualized as the column punches through the slab. Punching shear is very brittle and occurs all of a sudden. It is believed that the slab is subjected to hogging moments over the column in both directions, i.e. parallel and perpendicular to the free edge. Non-linear finite element analyses (NLFEA) has been used to study the cracking and failure mechanism for the reinforced slab. It is a slab over the edge support without clamping stiffness, therefore simulating the slab shear mechanism over a slender steel column is carried out in this study. The analyses has been performed using the software ATENA 3D Engineering developed by Červenka Consulting. Since the symmetry has been taken into account over an edge column, only one half of the cross-section has been modeled, with a symmetry line passing vertically through the slab and column. It can be summarized that the failure encountered around the column has a conical shape crack pattern similar to the ones encountered when punching shear occurs. However, it is important to note that this failure is not due to classic punching shear, but instead due to shear cracks developing around the column in both directions, both parallel and perpendicular to the free-edge. Three models (C1, C2, and C3) are studied to evaluate the impact that the length of the lower leg of the c-bar reinforcement has during failure. As mentioned earlier above, the crack propagation during punching shear begins from the upper surface of the slab and prolongs downwards diagonally towards the bottom of the slab and adjacent to the column. However, the crack propagation in the strip perpendicular to the free edge in all three models initiate from the bottom and propagate upwards. It can be concluded that the length reduction of the lower leg of the c-bars as a consequence reduced the shear strength capacity of the slab around the steel-plate. The reason for this is due to a reduction in maximum peak load when the lower leg of the c-bars were reduced. Consequently, this leads to a decrease in shear strength capacity of the slab and an earlier failure, where the inner-span was not able to take additional loads which could have led to greater deflections.Genomstansning är en brottmekanism orsakad av koncentrerade laster, vilket skapar ett sprickmönster i likhet med en konfrom ellet en bit av paj som börjar från den övre ytan av plattan och förlängs nedåt. När den totala skjuvkraften är större än skjuvmotståndet i plattan , kan det så småningom leda till ett genomstansningsbrott. Det kan visualiseras som att pelaren stansar eller slår igenom plattan. Genomstansning är ett mycket sprött brott och inträffar helt plötsligt. Det antas att plattan utsätts för negativt moment ovanför pelaren i båda riktningarna, d.v.s såväl parallellt som vinkelrät mot den fria kanten. Icke-linjära finita elementanalyser (NLFEA) har använts för att studera sprickbildnings och brottmekanismen för den förstärkta plattan. Det är en platta över kantstödet utan någon fast inspänd styvhet, därför simuleras skjuvmekanismen för plattan över en slank stålpelare i denna studie. Analyserna har utförts med programvaran ATENA 3D Engineering som utvecklats av Červenka Consulting. Eftersom hänsyn har tagits till symmetrin över en kantpelare har endast halva tvärsnittet modellerats, med en symmetrilinje som går vertikalt genom plattan och pelaren. Det kan sammanfattas att brottet som påträffas runt pelaren har en konisk form med ett sprickamönster som liknar de som påträffas vid genomstansning. Det är dock viktigt att notera att detta brott inte orsakats av klassisk genomstansning, utan istället på grund av skjuvsprickor som utvecklast runt pelaren i båda riktningarna, såväl parallellt som vinkelrät mot den fria kanten. Som det tidigare nämnts ovanför börjar sprickan vid genomstansning från plattans övre yta och förlängs nedåt diagonalt mot bottenplattan och intill pelaren. Sprickmönstret i remsan vinkelrät mot den fria kanten i alla tre modellerna (C1, C2 och C3) initierar dock från botten och sprids uppåt. Slutsatsen kan dras att längdminskningen av c-stängernas underben minskade skjuvhållfastheten hos betongplattan runt pelaren. Anledningen till detta beror på en minskning av maximal toppbelastning när c-stängernas underben reducerades. Följaktligen leder detta till en minskning av skjuvhållfastheten och ett tidigare brott, där den inre spännvidden inte kunda ta ytterligare belastningar som kunde ha lett till större nedböjningar.
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Pettigrew, Christopher S. "Flexural, Shear, and Punching Shear Capacity of Three 48-Year-Old Prestressed Lightweight Concrete Double-Tee Bridge Girders." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3852.
Full textAbstract:
The Icy Springs Bridge in Coalville, Utah carries 2nd South Street over the Weber River west of Interstate 80. The bridge is owned by Coalville City and was originally constructed in 1965 as a single-span 51-foot long bridge using prestressed concrete double-tee girders. In the fall of 2013 the original bridge was replaced with a new 80-foot long single span bridge using prestressed concrete decked bulb-tee girders. The original girders were salvaged and transported to the Systems, Materials, and Structural Health Lab (SMASH Lab) where a series of tests were performed to determine the total losses in the prestressing of the strands, the flexural and shear capacities of the girders, and the punching shear capacity of the reinforced concrete deck. The results of these tests were compared to the values calculated using methods outlined in the 2012 American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specifications, the current bridge design code used by most departments of transportation, and a finite element model using the computer program ANSYS. For the shear and punching shear test results, the AASHTO LRFD Bridge Design Specifications was conservative and was able to predict the type of failure that occurred. However, the tested flexural results were below the calculated flexural capacities using the AASHTO LRFD Bridge Design Specifications. A finite element model was created and calibrated to the test results for the various loading and support conditions. The actual tested material properties were compared to the material properties used in the finite element analyses to determine the difference between the actual girders and the theoretical models. Funding for this project was provided by the Utah Transportation Center.
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Zorlu, Merve. "Evaluation Of Punching Shear Strength Design And Modelling Approaches For Slab-column Connections." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614889/index.pdf.
Full textAbstract:
Flat plate systems are constructed with slabs directly supported on columns. Since
there are no beams in the system, the behavior of connections between the slabs and
columns play a crucial role. Due to the sudden and brittle nature of punching shear
failures, slab-column connection design must be conducted with proper safety
precautions. The first part of this study aims to evaluate the safety level of different
design expressions in the codes. Fir this purpose, the ability of ACI 318-11, TS-500
and Eurocode-2 to estimate punching shear strength was examined in light of
experimental results compiled from previous research. Interior and exterior
connections were examined in the course of the study. In the second part of the
study, beam and shell models were calibrated to simulate the load-deformation
response of interior slab-column connections in light of experimental results. In the
final part of this thesis, a typical floor plan of a flat plate system was analyzed to
investigate the possibility of a progressivefailure mechanism after punching failure
takes place at a slab-column connection. Minimum post-punching capacity required
to avoid progressive punching failure in a floor was estimated. It is believed that, the
results of this study can be helpful in guiding engineers in understanding the safety
inherent in punching shear design expressions and to take necessary precautions
against progressive collapse.
30
Šalna, Remigijus. "Influence of steel fibers on punching shear strength of beamless reinforced concrete slabs." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20081119_134617-00531.
Full textAbstract:
The dissertation examines the influence of steel fibers on the punching shear strength of reinforced concrete slabs. The analysis of punching shear models and strength-deformation models of composite materials was used for research. Also, punching shear experimental tests of real dimensions were made. The aim of dissertation is to propose the punching shear strength model, estimating type, strength, different anchoring and geometrical characteristics of steel fibers, as well as plastic strains of steel fiber reinforced concrete. To implement the aim of the paper, the following tasks were solved: stress and strain state of existing punching shear strength models were analyzed, strength-deformation models of composite materials were explored, experiments to confirm the suggested model were conducted.
The dissertation consists of six chapters including the final chapter of conclusions.
First chapter is dedicated to the introduction of the problem and its topicality. Also, purposes and tasks of the paper are formulated, the methods employed and the novelty of solutions is described, the author‘s publications and dissertation structure is presented.
Second chapter covers the analysis of existing punching shear strength methods and models. The aim and tasks of the work are formulated in the end of the chapter.
The third chapter describes theoretical investigation of steel fiber reinforced concrete strength-deformation characteristics. Based on the accomplished analysis, theoretical... [to full text]Disertacijoje nagrinėjama dispersinio armavimo įtaka gelžbetoninių besijinių perdangos plokščių praspaudimo stipriui. Tyrimams buvo naudota literatūroje pateikiamų praspaudimo bei kompozitinių medžiagų stiprio bei deformacijų skaičiavimo modelių analizė. Taip pat atlikti realių matmenų eksperimentiniai plokščių praspaudimo tyrimai. Disertacijos darbo tikslas – pasiūlyti praspaudimo stiprio skaičiavimo modelį, leidžiantį įvertinti dispersinės armatūros tipą, jos stiprį, skirtingas inkaravimosi ir geometrines savybes bei dispersiškai armuotame betone pasireiškiančias plastines deformacijas. Siekiant šio tikslo buvo sprendžiami tokie uždaviniai: atlikta praspaudimo skaičiavimo metodų bei esamų praspaudimo modelių įtempių ir deformacijų būvio analizė, dispersiškai armuoto betono stiprio bei deformacijų esamų modelių ir metodų analizė, atlikti eksperimentiniai tyrimai modeliui patikrinti. Disertaciją sudaro šeši skyriai. Paskutinysis iš jų – rezultatų apibendrinimas. Pirmajame (įvadiniame) skyriuje nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas ir uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi autoriaus pranešimai bei publikacijos, disertacijos struktūra. Antrasis skyrius skirtas praspaudimo skaičiavimo metodų ir modelių analizei. Jo pabaigoje formuluojami disertacijos uždaviniai. Trečiajame skyriuje teoriškai nagrinėjamos dispersiškai armuoto betono stiprio ir deformacinės savybės. Atliktus analizę pasiūlytas dispersiškai armuoto betono stiprio ir... [toliau žr. visą tekstą]
31
Ngekpe, B. E. "Punching shear failure of reinforced concrete flat slabs supported on steel edge column." Thesis, Coventry University, 2016. http://curve.coventry.ac.uk/open/items/5f0f9112-1838-448f-a245-cacc0bc3a9f5/1.
Full textAbstract:
This study examines punching shear failure at edge supported flat slab. Due to the significant dearth of research on punching shear at edge steel column, this study focuses on the design and performance of a novel shearhead system proposed for edge connection. By considering multi-stage processes and parameters that influence punching shear failure, both numerical and experimental studies were adopted. Firstly linear finite element analysis was employed to study the relationship between the continuous structure and the representative specimen; in order to support decisions on boundary conditions that create the similitude. A nonlinear (NLFEA) model was proposed where various concrete material constitutive models were compared and contrasted. The Total Strain crack model was adopted on the ground that it accounts for the tensile strength of cracked concrete which was ignored in previous theoretical model that lead to poor prediction of punching shear. By considering the appropriate material constitutive model for concrete and steel, material parameters, appropriate modelling scheme capable of predicting punching shear was formulated. The adopted modelling scheme was validated using previous research work. Numerical results reveal that punching shear is influenced most significantly by concrete tensile strength, fracture energy. The shearhead assembly was design with using ACI318-05 and Newzealand codes recommendations with some modifications. These are only codes that provide design guidance on shearhead. Experimental and numerical results show that the shearhead contributes appreciably to punching shear capacity of the edge connection. Various design codes on punching shear were compared; Eurocode 2 provides a good prediction of punching shear at edge support; which correlate well with experimental result. Hence, it was adopted to propose an equation for punching shear for edge connection with shearheads. Most importantly, appropriate design guidance and analytical equation have been proposed for shearhead connection. The design guidance and equation would enable practising Engineers to design shearheads without going through the rigor of experimental or numerical investigation. This study has contributed appreciably to the applicability of steel column in flat slab construction.
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Grira, Mongi. "A critical review of the symmetric punching shear of reinforced concrete flat slabs." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/6038.
Full textAbstract:
An experimental investigation on model slabs and on a 1/3 scale composite bridge deck showed that the ultimate punching shear load depends on the shape of the loaded area, the compressive strength of concrete, the flexural reinforcement ratio and on the arrangement of steel bars. Punching failure follows the formation of an inclined failure surface from the edge of the loaded area to the opposite slab face running through the effective depth at a mean angle of 22 to 30 degrees. A study of the application of the yield line theory proves that flexure theory alone is not recommended to treat local failure because of the violent and nonductile nature of punching shear failure. An explanation of the application of the strut and tie model to symmetric punching shear is given to provide a base for future experimental programs and the development of this approach. The mechanism of symmetric punching of slabs without shear reinforcement is described based on observations from tests. An empirical equation to determine the ultimate punching load of flat slabs is proposed. It is concluded that the proposed equation can predict the ultimate punching shear loads of flat slabs with confidence similar to Kinnunen and Nylander's model. Present North American codes should be updated to express the state of present day knowledge, particularly with the inclusion of the influence of the flexural reinforcement. (Abstract shortened by UMI.)
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Sudarsana, I. Ketut. "Punching shear in edge and corner column slab connections of flat plate structures." Thesis, University of Ottawa (Canada), 2001. http://hdl.handle.net/10393/6326.
Full textAbstract:
The behavior and strength of edge and corner column slab connections of flat plate structures subjected to shear force only, moment only as well as combined shear force and moment were investigated. A two bay by two bay flat plate structure (nine columns) and eight isolated edge column slab connections were constructed and tested to failure. After the tests of the four edge column connections of the continuous slab were completed, the edge connections were repaired using two types of concretes (normal concrete and CAB expansive concrete) and tested to failure. Interaction diagrams between shear force and unbalanced moment at edge column slab connections based on building code provisions (ACI 318-99, CSA A23.3-94 and CEB-FIP MC90) and three alternative approaches (Regan's approach, the Truss Model and the Strip Model) proposed in the literature are examined using the results of the present experimental work. Interaction diagrams for corner connections calculated using Regan's approach and the building code provisions are compared with the experimental results. The shear strength of edge and corner connections is calculated according to ACI 318-99, CSA A23.3-85, BS8110-85, CEB-FIP MC90 and the alternative approaches of Regan, Sherif, Gardner, Elgabry, the Truss Model and the Strip Model. All alternative approach predictions of shear strength of edge connections, except Sheril's, are conservative. The average ratio of measured shear strength to calculated shear strength ranges from 0.90 to 1.30 with coefficients of variation (COV) ranging from 0.18 to 0.40. Gardner's approach, that considered a linear shear stress distribution as in ACI 318-99, with a critical shear section taken at the column perimeter or perimeter of loaded area gives the most conservative and the least scatter of the test results compared with the other proposed approaches. The measured shear strengths of the corner connections are compared to the calculated shear strengths based on the building code provisions and five alternative approaches available in the literature (i.e. Ingvarsson's, Regan's, Zaghlool's, Gardner's and Desayi's approach). On the basis of the present test results, the effects of load eccentricity (M/V) and reinforcement ratio (rho avg) on shear strength of edge column slab connections are investigated. The reduction in shear capacity of edge connections due to the increase in M/V ratios approximates a logarithmic function. The effect of the reinforcement ratio on the shear strength of the present tests on the edge and corner connections calculated using the North American codes is not obvious. However, tests by Zaghlool (1973) and Regan (1981) show that the shear strength increased with an increase in reinforcement ratio. The strength and stiffness of repaired edge connections were investigated using the four, previously failed, edge connections of the continuous slab specimen. Connections repaired using normal concrete can have similar strength and stiffness as the original connections. However, the connections repaired using the CAH expansive concrete exhibited less strength and stiffness compared to the original edge connections.
34
Zhang, Xuesong, and n/a. "Punching Shear Failure Analysis of Reinforced Concrete Flat Plates Using Simplified Ust Failure Criterion." Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051104.153239.
Full textAbstract:
Failure criteria play a vital role in the numerical analysis of reinforced concrete structures. The current failure criteria can be classified into two types, namely the empirical and theoretical failure criteria. Empirical failure criteria normally lack reasonable theoretical backgrounds, while theoretical ones either involve too many parameters or ignore the effects of intermediate principal stress on the concrete strength. Based on the octahedral shear stress model and the concrete tensile strength under the state of triaxial and uniaxial stress, a new failure criterion, that is, the simplified unified strength theory (UST), is developed by simplifiing the five-parameter UST for the analysis of reinforced concrete structures. According to the simplified UST failure criterion, the concrete strength is influenced by the maximum and intermediate principal shear stresses together with the corresponding normal stresses. Moreover, the effect of hydrostatic pressure on the concrete strength is also taken into account. The failure criterion involves three concrete strengths, namely the uniaxial tensile and compressive strengths and the equal biaxial compressive strength. In the numerical analysis, a degenerated shell element with the layered approach is adopted for the simulation of concrete structures. In the layered approach, concrete is divided into several layers over the thickness of the elements and reinforcing steel is smeared into the corresponding number of layers of equivalent thickness. In each concrete layer, three-dimensional stresses are calculated at the integration points. For the material modelling, concrete is treated as isotropic material until cracking occurs. Cracked concrete is treated as an orthotropic material incorporating tension stiffening and the reduction of cracked shear stiffness. Meanwhile, the smeared craclc model is employed. The bending reinforcements and the stirrups are simulated using a trilinear material model. To verify the correctness of the simplified UST failure criterion, comparisons are made with concrete triaxial empirical results as well as with the Kupfer and the Ottosen failure criteria. Finally, the proposed failure criterion is used for the flexural analysis of simply supported reinforced concrete beams. Also conducted are the punching shear analyses of single- and multi-column-slab connections and of half-scale flat plate models. In view of its accuracy and capabilities, the simplified UST failure criterion may be used to analyse beam- and slab-type reinforced concrete structures.
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Bono, Matthew P. (Matthew Paul). "Tilt-up concrete panels : an investigation of flexural stresses and punching shear during lifting." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/66823.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 75).
Tilt-up construction is becoming more popular in the United States due to its ease of construction, reliability, and relatively low construction and maintenance costs. In its most typical form, a concrete panel is cast on the ground. After the concrete sets and has reached a prescribed compressive or flexural strength, a crane lifts the panel off the ground and hoists it into place. The flexural stresses during liftoff are often times greater than those corresponding to service loads. Concentrations of high shear stress and the associated punching shear in the vicinity of the pick points could result in pullout. For these reasons, it is particularly important to design the concrete and steel reinforcement to handle the flexural and shear stresses associated with panel erection. This thesis investigates the flexural stresses and punching shear of a concrete panel designed for tilt-up. Finite element models confirm static hand calculations, and experimental results indicate that these models appropriately predicted erection stresses. The acceptability of the design provided is confirmed.
by Matthew P. Bono.
M.Eng.
36
Vosoughian, Saeed. "The effect of pre-stressing location on punching shear capacity of concrete flat slabs." Thesis, KTH, Betongbyggnad, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263243.
Full textAbstract:
Implementing pre-stressing cables is a viable option aiming at controlling deformation and cracking of concrete flat slabs in serviceability limit state. The pre-stressing cables also contribute to punching shear capacity of the slab when they are located in vicinity of the column. The positive influence of pre-stressing cables on punching capacity of the concrete slabs is mainly due to the vertical component of inclined cables, compressive in-plane stresses and counter acting bending moments near the support region. The method presented in Eurocode 2 to determine the punching capacity of the pre-stressed concrete flat slabs considers the in-plane compressive stresses but totally neglects the effect of counter acting moments. The effect of vertical forces introduced by inclined cables is only considered when they are within the distance 2d from the face of the column. This area is called basic control area in the Eurocode 2. In this master thesis nonlinear finite element analysis is carried out to study the effect of pre-stressing cables on punching shear capacity of concrete slabs respecting the distance of cables from the face of the column. To attain this objective, the concrete damage plasticity model is implemented to model the concrete. The results indicate that until the distance of 6d from the face of the column the contribution of pre-stressing cables in punching shear capacity of slabs is significant. Furthermore, comparing the numerical results with the punching shear capacity of slabs predicted by Eurocode 2 reveals that Eurocode tremendously underestimates the punching shear capacity when the cables are located outside the basic control area.
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ElGendy, Mohammed. "Punching shear behaviour of slab-column edge connections reinforced with fibre-reinforced polymer (FRP) composite bars." Canadian Society of Civil Engineering, 2014. http://hdl.handle.net/1993/24092.
Full textAbstract:
The use of fibre reinforced polymer (FRP) composites as an alternate to steel has proved to be an effective solution to the corrosion problem. However, FRP bars have low axial and transverse stiffness compared to steel bars which results in a lower shear capacity of FRP reinforced concrete (RC) elements compared to steel-RC elements.
Flat plate systems are commonly used to take advantages of the absence of beams. They, however, are susceptible to punching shear failure where the column suddenly punches through the slab.
An experimental program was conducted to investigate the punching shear behaviour of slab-column edge connections. Nine isolated full-scale slab-column edge connections were constructed and tested to failure. One connection was reinforced with steel flexural reinforcement, six with GFRP flexural reinforcement and two with GFRP flexural and shear reinforcement. The parameters investigated were the flexural reinforcement type and ratio, the moment-to-shear ratio and the shear reinforcement spacing.
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Fernández, Sánchez Pablo Gonzalo. "Study on the shear and punching-shear strength of reinforced concrete slabs subjected to point loads and in-plane tensile forces." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/673351.
Full textAbstract:
Reinforced concrete members, especially when subjected to concentrated loads, can fail in shear. This is an undesirable and brittle failure mode preventing the structure from deforming and reaching higher load levels. It is therefore important to investigate and understand the nature of shear failures in RC beams and slabs, which are typically not provided with shear reinforcement. Despite the exhaustive research work carried out since the beginning of the XXth century, the shear behavior of reinforced concrete elements is still not fully clear. The complex kinematics and the different contribution of the widely accepted shear resisting actions, which depend, among other parameters, on the load level and the geometry of the specimens, are part of those uncertainties that have provoked the lack of consensus that currently exist around the shear problem in structural engineering.
In this context, this thesis focuses on the shear behavior of reinforced concrete slabs without shear reinforcement subjected to point loads. On the one hand, part of the work carried out during this investigation deals with shear in one way slabs supported on linear supports. Thanks to the experimental work conducted in the last two decades, a significant database of test results is now available, which has allowed to develop and verify a new mechanical model to predict the shear strength of RC one-way slabs without shear reinforcement. It takes into account a significant number of variables involved in the phenomenon and is applicable to is applicable to simply supported slabs, cantilever slabs and situations with partial restraint to the rotation. The model is divided into two sub-models. One for loads applied close to supports, where the direct transmission of the load to the support plays an important role in the shear strength and a second one for loads applied away from supports where the possibility of a shear failure is assumed to coexist with the possibility of a local punching failure.
On the other hand, the second part of the investigation deals with the shear behavior of reinforced concrete slabs subjected to the simultaneous action of in plane tensile stresses and out-of-plane point loads. This load case has not been exhaustively studied throughout the years, and in order to contribute to gain insight into this aspects of shear design, the mechanical model recently developed at UPC for the prediction of the punching-shear strength of two-way slabs has been extended to the case of simultaneous in-plane tensile forces. A set of experimental test for the validation of the model for the particular case of uniaxial in-plane tension is also presented. In addition to that, the particular case of one-way simply supported slabs subjected to transverse tensile stresses has also been experimentally studied. This is a seldom studied load case and the conducted set of test will help to understand the overall behavior of these elements under this particular loading condition.Los elementos de hormigón armado, especialmente cuando están sometidos a la acción de cargas puntuales, pueden alcanzar su resistencia última a esfuerzo cortante, lo cual limita su capacidad para deformarse y resistir valores de carga mayores. Este es un modo de fallo frágil y repentino, por lo que debe ser evitado. Así pues, es importante seguir investigando y comprender la naturaleza de la respuesta de vigas y losas de hormigón armado ante solicitaciones de este tipo, sobre todo cuando no están provistas de armadura de cortante. A pesar de la gran cantidad de campañas experimentales llevadas a cabo desde principios del siglo XX, el comportamiento a cortante y punzonamiento de los elementos estructurales de hormigón armado no está todavía del todo claro. La compleja cinemática y la diferente contribución de los mecanismos resistentes ampliamente aceptados, la cual depende, entre otros factores, del nivel de carga y de la geometría de los especímenes, son parte de esas incertidumbres que han provocado la falta de consenso que existe actualmente dentro del campo de la ingeniería estructural. En este contexto, esta tesis se centra en el comportamiento a cortante de losas de hormigón armado sin armadura de cortante sometidas a la acción de cargas puntuales. Por un lado, parte del trabajo realizado durante esta investigación está orientado al cortante en losas unidireccionales apoyadas sobre apoyos lineales. Gracias a todas las campañas experimentales realizadas en las últimas dos décadas, una significativa base de datos de resultados experimentales se encuentra disponible en la literatura, lo que ha permitido desarrollar y verificar un nuevo modelo mecánico para predecir la resistencia última a cortante de este tipo de elementos. Dicho modelo tiene en cuenta un número importante de variables involucradas en el fenómeno y es aplicable a losas simplemente apoyadas, en ménsula, y apoyadas en apoyos con restricción parcial al giro. El modelo se ha dividido en dos sub-modelos para facilitar su desarrollo. Uno para cargas aplicadas cerca de los apoyos, donde la transmisión directa de la carga al apoyo juega un papel importante, y un segundo para cargas aplicadas lejos de los apoyos, en donde se asume que la posibilidad del fallo por cortante coexiste con la posibilidad de un fallo local por punzonamiento. Por otro lado, la segunda parte de la investigación está focalizada en el comportamiento a cortante de losas de hormigón armado sometidas simultáneamente a la acción de cargas puntuales y tracciones en su plano. Este caso de carga no ha sido demasiado investigado a lo largo de las últimas décadas, y con la intención de contribuir a comprender esta compleja interacción, el modelo mecánico recientemente desarrollado en la UPC, para la predicción de la resistencia a punzonamiento en losas bidireccionales, ha sido extendido a este caso particular de cargas y validado con los resultados de campañas experimentales disponibles en la literatura y el conjunto de ensayos realizados como parte de esta investigación para el caso particular de tracciones unidireccionales. Adicionalmente, el efecto de las tracciones transversales en el plano en la resistencia a cortante de losas unidireccionales también ha sido estudiado experimentalmente. Esta combinación de cargas no ha sido apenas investigada y un nuevo grupo de ensayos experimentales puede contribuir a comprender el comportamiento global de este tipo de elementos ante este caso particular de carga.
Enginyeria de la construcció
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Schreiber, Sascha K. "Punching shear capacity of slab-column connections with steel-fibre reinforcement under lateral cyclic loading." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60493.pdf.
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Pei, Shuangxi. "An investigation into the punching shear failure in R.C. waffle slabs subjected to concentrated load." Thesis, University of Abertay Dundee, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240614.
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Schmidt, Philipp [Verfasser], Josef [Akademischer Betreuer] Hegger, and Jürgen [Akademischer Betreuer] Feix. "Punching in shear-reinforced flat slabs and column bases / Philipp Schmidt ; Josef Hegger, Jürgen Feix." Aachen : Universitätsbibliothek der RWTH Aachen, 2020. http://d-nb.info/1227993129/34.
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Samad, Shahab. "Engineering properties of binary cement concretes and their effect on punching shear of flat slabs." Thesis, Kingston University, 2013. http://eprints.kingston.ac.uk/26572/.
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Concrete is the most important building material in the world due to the fact that it is versatile and gives architectural freedom. For sustainable construction solutions concrete is the material of choice if the embodied CO2 content is considered. In concrete, cement is the main constituent and due to the limit on the availability of natural minerals used, the energy released and the CO2 emissions produced during its manufacture, it can be partially replaced using industrial by-products e.g. Pulverised Fuel Ash (PFA), Ground Granulated Blast furnace Slag (GGBS) and silica fume. The effects of the partial replacement of cement with these industrial by products on fresh and hardened properties of concrete cured under summer and winter environments are established and compared with the Portland cement (PC) concrete. Early age strength of concrete containing GGBS and PFA is less than the PC concrete, which would prevent its use in the in the post tensioned concrete and in fast-track construction, where early removal of formwork, or early application of load to the structure are the main requirements. For this reason, and due to the demand of high strength concrete in construction, for its improved durability properties, concrete containing GGBS and PFA was produced by keeping the water/cement ratio low and a superplasticiser was used to achieve the required workability. At low water/cement ratio, concrete containing GGBS up to 50 % and PFA Lip to 30 % can achieve the required early age strength for the removal of formwork if cured properly. At the age of 28 days, the flexural strength and modulus of elasticity of concrete in which PC is partially replaced with GGBS and PFA are increased in comparison to where this is not carried out. For practical applications of the sustainable concrete mixes in structural concrete production and due to the limited data availability on punching shear strength, concrete containing GGBS and PFA in flat slab specimens were tested for this property. In flat slabs without beams, the design criteria is often the resistance against punching shear failure at the column/slab connection. Punching failure is the separation of the portion of the slab surrounding the column from the rest and is a brittle failure. Experimental punching shear results are compared to the estimates of BS 8110, BS EN1992-1-1 and ACI 318 and it was found that the estimates of ACI318 and BS 8110, ignoring the partial safety factors, are close to the experimental results and the estimates of BS EN 1992-1-1 are over conservative. Based on the test results of punching shear resistance of flat slabs, and the materials used, it is concluded that concrete containing GGBS up to 50 % and PFA up to 30 % can be used in flat slabs without any special design requirements and the design rules given in different codes of practice can be used without modifications. It is evaluated that for a concrete, designed for characteristic strength of 30 MPa, a reduction of 152 kg/m3 of CO2 and 0.65 GJ/m30f energy consumption can be achieved by replacing PC with 50 % GGBS and a reduction of 62.5 kg/m3 of C02 and 0.27 GJ/m3 of energy can be achieved by using 30 % PFA concrete.
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Hassan, Mohamed Ashour Wardany. "Punching shear behaviour of concrete two-way slabs reinforced with glass fiber-reinforced polymer (GFRP) bars." Thèse, Université de Sherbrooke, 2013. http://hdl.handle.net/11143/6129.
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Deterioration of reinforced-concrete (RC) structures due to corrosion of steel limits the service-life and increases the rehabilitation costs. Concrete slabs in parking structures deteriorate faster than any other structural elements because of direct exposure to high concentrations of chlorides used for snow and ice removal-during winter seasons. The use of fiber-reinforced polymer (FRP) bars as an alternative to conventional steel has emerged as a realistic and cost-effective solution to overcome the corrosion problems, particularly for concrete structure exposed to harsh environmental conditions. Design of RC flat slabs is often compromised by their ability to resist shear stresses at the punching-shear surface area. The connections between slabs and supporting columns could be susceptible to high shear stresses and might cause brittle and sudden punching-shear failure. These connections may become the starting points leading to catastrophic punching-shear failure of a flat slab system when the steel reinforcement corrodes. Extensive research work has been conducted on the punching-shear behaviour of steel-reinforced flat slabs. The punching-shear strength of RC flat slabs reinforced with glass fiber-reinforced polymer (GFRP) bars, however, is yet to be fully investigated and understood. This is due to the limited research work on the subject and to the numerous parameters affecting punching-shear behaviour. In addition, the current FRP design codes and guidelines do not provide rational design models addressing the contribution of the FRP as shear reinforcement (stirrups) for FRP-RC flat slabs. Thus, this study aims at investigating the punching-shear behaviour of concrete two-way slabs reinforced in flexure with GFRP bars. The investigation included two-way test specimens without shear reinforcement and others with carbon or glass FRP stirrups to evaluate the performance of specimens without shear reinforcement and the effect of shear reinforcement on the punching-capacity and performance. To achieve this, experimental and analytical studies were conducted. The experimental program included twenty-six interior slab-column connections reinforced with GFRP bars and two specimens reinforced with steel bars for comparisons. The specimens were tested through two phases. Phase I, focused on the two-way slabs without shear reinforcement and the investigated parameters were: (i) flexural reinforcement ratio (ranged from 0.34% to 1.66%) and type (steel and GFRP); (ii) GFRP compression reinforcement; (iii) slab thickness (200 mm and 350 mm); (v) column dimensions (300 × 300 mm and 450 × 450 mm); (iv) concrete strength (normal and high-strength concretes). Phase II, focused on the use of FRP shear reinforcement (stirrups) and its effectiveness and contribution to the punching-shear capacity. The test variables considered in Phase II were: (i) the material of stirrups (carbon and glass FRP); (ii) shear reinforcement ratio; (iii) stirrup spacing; (iv) the effect of flexural reinforcement ratio on the effectiveness of the shear reinforcement. The effect of the different parameters considered in the two phases of the experimental work were presented and discussed in four journal papers. Moreover, the test results and the findings contributed to the first field implementation of GFRP bars in two flat slabs parking garages in Québec's city, which were Québec's city hall (Québec, Canada, 2010) and La Chancelière parking garage (the world's first flat-slab parking garage totally reinforced with GFRP bars) (Québec, Canada, 2011). On the other hand, the analytical study included assessing the accuracy of the current punching-shear design provisions through comparing the test results of the specimens tested herein and 35 specimens from literature. The provisions included CSA 8806-12 (2012), ACI 440 (2006), BS 8110 (1997), and JSCE (1997).
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Lim, Boon Tiong. "Punching shear capacity of flat slab-column junctions (a study by 3-D non-linear finite element analysis)." Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/1708/.
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This thesis presents a study of punching shear capacity of flat slab-column junctions. A three dimensional non-linear finite element program based on 20 node isoparametric solid element was used for the investigation. The non-linear 3-D elastic isotropic model proposed by Motsovos was used to describe the behaviour of concrete before cracking or crushing. After cracking, a yield criteria for 2-D model similar to Kupfer-Hilsdorf was used and concrete was assumed to be anisotropic. No softening in compression is assumed. Smeared crack approach with simple tension stiffening and shear retention equations were employed to mimic the post-cracking behaviour of concrete. Reinforcing bars were represented by one dimensional element embedded in the solid elements and for both tension and compression, linear elastic-plastic behaviour is assumed. A comparison was first made between the predictions of slab behaviour using Kotsovos' model (In-house program) and plasticity based model used in the commercial package ABAQUS. From this it was concluded that Kotsovos' concrete model is a good model for the three dimensional analysis of the punching shear problem but the ABAQUS model was unsuitable. In order to achieve an accurate and economical solution for the non-linear analysis, a parametric study was carried out to choose a suitable analytical model. After having chosen the "best" concrete model, over 175 slabs from different sources were analysed using a constant set parameters. The analysis includes various types connections (interior, edge and corner) with and without shear reinforcement, subjected to shear force alone or to a combination of shear force and unbalanced moment. These slabs cover most of the factors affecting punching shear strength, such as slab thickness, flexural reinforcement ratios, concrete strength, and column size. This study also includes the effect of in-plane restraint on punching shear strength of slabs.
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Labib, Wafa Abdelmajeed. "An experimental study and finite analysis of punching shear failure in steel fibre-reinforced concrete ground-suspended floor slabs." Thesis, Liverpool John Moores University, 2008. http://researchonline.ljmu.ac.uk/5893/.
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The present research is concerned with investigating the structural effect of using steel fibre-reinforcement on the punching shear behaviour of ground-suspended slabs with internal columns. The main objectives of this research were to develop a constitutive model for steel fibre-reinforcement (SFRC), to study experimentally the punching shear behaviour of SFRC with no longitudinal reinforcement and to develop a finite element model that can accurately predict the behaviour of SFRC slabs subjected to punching shear. In this respect, a literature review of the work undertaken by previous researchers on punching shear behaviour of concrete slabs is presented. After that, a constitutive model for SFRC was developed. This is followed by a preliminary finite element analysis (FEA) and experimental study of SFRC slabs. Finally, a finite element model was developed. The literature review revealed that little work has been carried out to study the effect of fibre-reinforcement on the punching shear capacity of concrete slabs. Furthermore, structures, hence a thorough investigation in this area was mandatory. A constitutive model for SFRC in post-cracking stage was developed. This enables one to estimate the tension stiffening behaviour of SFRC based on a simple beam bending test and a statistical model developed in this research, this constitutive model was used later on in the modelling of the SFRC slabs using FEA. In the preliminary FEA, sufficient information for the size and the design of test specimens that were used in the experimental programme was produced. In the experimental study, eight steel fibre-reinforced concrete slab-column connection specimens were tested. The variables of the test specimens include the concrete compressive strength, fibre dosage and fibre aspect-ration.
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Silva, Carolina Ribeiro da. "Punção em lajes de concreto armado com furo e transferência de momento: comparação de normas." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-12032018-085200/.
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O crescente uso de lajes sem vigas (lisa com ou sem capitel) como solução estrutural de edificações, justificado por questões econômicas e construtivas, têm destacado a importância do estudo desses elementos estruturais. Já as desvantagens desse sistema estrutural estão associadas às altas tensões geradas na região próxima dos pilares, originando o fenômeno de punção. As normas atuais especificam uma seção íntegra resistente para dimensionamento à punção, entretanto, devido principalmente à passagem de instalações hidráulicas e elétricas através dos pavimentos, é necessária a execução de furações, em alguns casos muito próximas ao contorno dos pilares, o que implica diretamente na redução dessa seção e da resistência das lajes. Portanto, são necessários modelos de cálculo específicos para isso. A NBR 6118 tem critérios para esse problema, mas são antigos e precisam ser modernizados. Assim, comparando os dados experimentais de algumas pesquisas com as cargas últimas estimadas para normas vigentes (fib MC2010:2013, EC2:2004, ACI-318:2014 e NBR 6118:2014), este trabalho teve como objetivo identificar limitações das normas estudadas e verificar a eventual possibilidade de melhorias. Com base nos resultados observados foi proposta uma alteração para a NBR 6118: 2014 no cálculo da punção para lajes lisas com furo(s) na região do pilar, de modo que seja considerado no dimensionamento o momento gerado pela excentricidade do perímetro crítico devido à presença de furo(s) na laje.The increasing use of flat slabs (slabs without beams with or without drop panel) as a structural solution of buildings, justified by economic and constructive issues, has highlighted the importance of the study of these structural elements. The disadvantages of this structural system are associated with high stresses generated in the region near of the columns, causing the punching shear phenomenon. The current standards specify a resistant section for punching shear design, however, due mainly to the passage of hydraulic and electric installations through the floors, it is necessary to execute holes, in some cases very close to the boundaries of the columns, which reduces this section and the slab strength. Therefore, it is necessary to specify calculation models for that. The NBR 6118 has criteria for this problem, nonetheless it is old and needs to be modernized. Comparing experimental data from some researches, with the estimated ultimate loads for current standards (fib MC2010: 2013, EC2: 2004, ACI-318: 2014 and NBR 6118: 2014), this work had as objective to identify limitations of the standards studied and verify possible improvements. Based on the observed results, it was proposed a modification for NBR 6118: 2014 in the design of the punching shear of flat slabs with hole(s) near of the column, considering the moment caused by the eccentricity of the critical perimeter due to the presence of hole(s) in the slab.
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Melges, José Luiz Pinheiro. "Punção em lajes: exemplos de cálculo e análise teórico-experimental." Universidade de São Paulo, 1995. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-25042018-115908/.
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Atualmente, alguns códigos como o CEB/90 e o texto base da NB-1/94 (ainda em fase de apreciação pelo meio técnico) têm apresentado inovações com relação à verificação da resistência à punção. Fez-se então, neste trabalho, uma análise do texto base da NB-1/94 referente à punção, comparando suas recomendações com algumas das fornecidas pelo CEB/90. Observou-se uma certa divergência entre os dois códigos com relação a pilares de borda e de canto, fornecendo o CEB/90 um tratamento mais simplificado para essas duas situações. Além disso, observa-se que, ao contrário do CEB/90, o texto base não menciona as seguintes recomendações: utilização de uma armadura a ser disposta ao longo das bordas livres da laje, destinada a combater esforços de torção, e limitação da resistência do concreto em 50 MPa para essas verificações. Observou-se, ainda, uma omissão desses dois códigos com relação à situação de pilares internos submetidos a momentos fletores atuando em duas direções diferentes. Sugere-se, ainda, ao texto base, a inclusão de expressões que visem a facilitar e agilizar a sua aplicação. Após essa análise, foram apresentados exemplos de cálculo para pilares internos, de borda e de canto, tanto com como sem armadura de punção, verificados segundo as recomendações do texto base da NB-1/94, do EUROCODE N.2, do CEB/90 e do ACI 318/89. Por fim, comparam-se resultados experimentais com valores dados por estes códigos, visando determinar suas respectivas eficiências frente a alguns parâmetros, tais como, por exemplo, a presença de armadura transversal ou a relação entre os lados do pilar. Verifica-se que a utilização de armaduras de combate à punção pode elevar substancialmente o valor da resistência da ligação, além de torná-la mais dúctil. As observações referentes à comparação entre os valores fornecidos através de ensaios e os dados pelos códigos devem ser levadas em consideração apenas como uma indicação de seus respectivos comportamentos, necessitando-se de mais dados para uma afirmação mais conclusiva.Nowadays, some standards like CEB/90 and the Brazilian code basic text NB-1/94 (not approved yet) have presented some innovations for the punching shear strength. In this work, a comparative analysis is presented about the NB1-94 basic text recommendations and some presented by the CEB/90. Some differences are noted between the NB1-94 basic text and the CEB/90 recommendations relatives to corner and edge columns. The CEB/90 has a simplified treatment for these situations. lt is noted that, in opposition to the CEB/90, the NB1-94 basic text about punching shear strength does not mention an additional reinforcement to be placed at the free edges of the slab, to provide torsion strength, and neither have a limit value of 50 MPa for the concrete compressive strength. lt is also noted that the CEB/90 and the NB1-94 basic text do not have a recommendation for internal columns with bending moments acting on two different directions. lt is suggested that the NB1-94 basic text includes some expressions that can make its application easier and faster. After this analysis, some examples are presented with internal, edge and corner columns, with and without shear reinforcement, verified by the NB1-94 basic text, the EUROCODE N.2, the CEB/90 and the ACI 318/89 recommendations. Finally, a comparative analysis between some experimental results and those given by the codes is presented. The experimental results were related to some parameters like, for instance, the presence of shear reinforcement or the column sides ratio. lt is verified that the shear reinforcement utilization can give more resistance and ductility to the connection. Finally, it is noted that the observations about the comparison between the experimental results and the values given by the codes can just be taken like a behavior indication for the connections. For conclusive affirmations, more experimental analysis are necessary.
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Kueres, Dominik [Verfasser], Josef [Akademischer Betreuer] Hegger, Boyan [Akademischer Betreuer] Mihaylov, and Robert [Akademischer Betreuer] Vollum. "Two-parameter kinematic theory for punching shear in reinforced concrete slabs / Dominik Alexander Kueres ; Josef Hegger, Boyan Mihaylov, Robert Vollum." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1180731204/34.
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Antunes, Filipe. "Estudo da perfuração de chapas grossas de aço ASTM A-36." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/173781.
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O presente trabalho estuda a variação do diâmetro inicial e diâmetro final de um furo puncionado feito em uma chapa de aço ASTM A-36 com 12,7 mm de espessura. São propostas três geometrias diferentes de punção fabricados em aço AISI D2 e AISI S1 com diâmetro inicial 20 mm e final 22 mm. Os punções foram fabricados para realizarem o processo de puncionamento e brochamento com penetrações de avanço (asf) de 0,2 mm, 0,5 mm e 1 mm. O objetivo principal é reduzir a conicidade dos furos puncionados atualmente através do método convencional. As folgas entre punção e matriz (w) utilizadas foram de 3,1%, 7,8% e 15,7% da espessura da chapa de testes respectivamente. Para avaliação do desempenho de cada ferramenta, todos os furos puncionados foram medidos e tabelados. Entre os resultados encontrados, constatou-se que os punções com brochamento apresentam melhores valores que os convencionais em todos parâmetros analisados. As regiões de cisalhamento (Zc) e região de ruptura abrupta (Zr) também sofreram influência direta em função da geometria utilizada.The present work studies the variation of the initial diameter and final diameter of a punched hole made in an ASTM A-36 steel sheet with 12.7 mm of thickness. Three different punches geometries are proposed and manufactured from AISI D2 and AISI S1 steel with initial diameter 20 mm and final diameter 22 mm. The punches were manufactured to carry out the punching and broaching process with feed penetrations (asf) of 0.2 mm, 0.5 mm and 1 mm. The main objective is to reduce the conicity of the punched holes currently through the conventional method. The clearance between punch and die (w) used were 3.1%, 7.8% and 15.7% of the thickness of the test plate respectively. To evaluate the performance of each tool, all punched holes were measured and tabulated. Among the results, it was observed that the punches with a broaching showed better values than the conventional ones in all analyzed parameters. The regions of shear (Zc) and region of abrupt rupture (Zr) also had a direct influence in function of the geometry used.
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Holanda, Kristiane Mattar Accetti. "Análise dos mecanismos resistentes e das similaridades de efeitos da adição de fibras de aço na resistência e na ductilidade à punção de lajes-cogumelo e ao cisalhamento de vigas de concreto." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-08022003-170132/.
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Um dos principais problemas das lajes-cogumelo refere-se à ruína por puncionamento da ligação laje-pilar. Esta forma de ruína deve ser evitada, proporcionando-se às lajes as melhores condições para o desenvolvimento de mecanismos de escoamento das armaduras e de ruína por flexão, antes da ocorrência da ruína por cisalhamento. A introdução de fibras de aço em elementos de concreto submetidos a solicitações tangenciais proporciona melhoria de desempenho, seja pelo aumento da capacidade resistente, seja pela alteração da forma de ruína. Pretende-se contribuir com o avanço do conhecimento sobre o assunto, explorando aspectos como a análise das similaridades dos efeitos da adição de fibras de aço na resistência e na ductilidade de lajes-cogumelo à punção, com aqueles que se observam no cisalhamento de vigas prismáticas análogas. Abordam-se os casos de ligações laje-pilar interno sem armadura de punção, variando-se a resistência do concreto, a taxa e o tipo de fibra utilizado. A partir dos resultados experimentais, verificou-se que existe uma similaridade de comportamento estrutural entre esses dois elementos e concluiu-se que é possível utilizar ensaios de cisalhamento em vigas prismáticas para se obter indicadores a serem utilizados nos ensaios de punção de lajes. Foi efetuada uma análise da adaptabilidade de modelos teóricos existentes sobre cisalhamento em vigas e punção em lajes, com vistas à consideração do efeito da adição de fibras de aço ao concreto. Com base nesses modelos, foram estabelecidos critérios quantitativos para avaliação da resistência e da ductilidade das ligações laje-pilar.One of the main problems of flat slabs concerns the punching shear failure of the slab-column connection. This form of failure must be avoided, providing flat slabs with the best conditions for the development of yielding mechanisms of the flexural reinforcement before the occurrence of shear failure. The addition of steel fibers to concrete elements subjected to tangential stress provides performance improvement, by either the resistant capacity increase or the failure mode alteration. It is intended to contribute to the advance of the subject knowledge, by exploring aspects as the analysis of similarities of the steel fiber addition effects on both strength and ductility of flat slabs to punching shear with those observed in the shear of analogous prismatic beams. The cases approached include internal slab-column connections without shear reinforcement, and the variables investigated included concrete strength, fiber volume and type of steel fiber. From the experimental results, it was possible to verify that there exists a similarity of structural behavior between these two elements and the shear tests in prismatic beams can be used to get indicators to be utilized in punching shear tests of flat slabs. An adaptability analysis of the existing theoretical models on shear in beams and punching shear in flat slabs was carried out in order to consider the steel fibers addition effect on the concrete. Based on these models, quantitative criteria for the evaluation of both strength and ductility of the slab-column connections were established.