Journal articles: 'Flexural punching'

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Ozden, Sevket, Ugur Ersoy, and Turan Ozturan. "Punching shear tests of normal- and high-strength concrete flat plates." Canadian Journal of Civil Engineering 33, no. 11 (November 1, 2006): 1389–400. http://dx.doi.org/10.1139/l06-089.

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Experimental research was conducted to investigate the punching shear performance of flat plates. A large number of slab specimens of normal- and high-strength concrete were tested under concentric and eccentric loads. The effects of flexural reinforcement and the use of steel fiber reinforcement were investigated. Experimental expressions were developed for the computation of residual slab strength. Experimentally observed punching shear capacities were compared with those from the provisions of Canadian Standards Association (CSA) standard CSA-A23.3-04. The results indicate that concrete strength plays an important role in punching capacity and slab rigidity. Slabs with a higher percentage of flexural reinforcement show an increase in punching capacity. The use of steel fibers results in improved strength and stiffness while also enhancing the postpeak deformability and residual strength. The empirical expressions developed provide reasonably good predictions of residual slab capacities. CSA-A23.3-04 expressions result in conservative punching shear capacity predictions for concentrically loaded slabs and provide good agreement with the experimentally observed punching shear capacities for eccentrically loaded slabs.Key words: reinforced concrete, flat plate, punching shear, strength, high-strength concrete, eccentric loading, slab re inforcement ratio, steel fiber reinforced concrete.

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Ju, Minkwan, Kyoungsoo Park, and Cheolwoo Park. "Punching Shear Behavior of Two-Way Concrete Slabs Reinforced with Glass-Fiber-Reinforced Polymer (GFRP) Bars." Polymers 10, no. 8 (August 9, 2018): 893. http://dx.doi.org/10.3390/polym10080893.

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This study investigated the punching shear behavior of full-scale, two-way concrete slabs reinforced with glass fiber reinforced polymer (GFRP) bars, which are known as noncorrosive reinforcement. The relatively low modulus of elasticity of GFRP bars affects the large deflection of flexural members, however, applying these to two-way concrete slabs can compensate the weakness of the flexural stiffness due to an arching action with supporting girders. The test results demonstrated that the two-way concrete slabs with GFRP bars satisfied the allowable deflection and crack width under the service load specified by the design specification even in the state of the minimum reinforcement ratio. Previous predicting equations and design equations largely overestimated the measured punching shear strength when the slab was supported by reinforced concrete (RC) girders. The strength difference can be explained by the fact that the flexural behavior of the supporting RC beam girders reduces the punching shear strength because of the additional deflection of RC beam girders. Therefore, for more realistic estimations of the punching shear strength of two-way concrete slabs with GFRP bars, the boundary conditions of the concrete slabs should be carefully considered. This is because the stiffness degradation of supporting RC beam girders may influence the punching shear strength.

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Pang, Rui, Longji Dang, Hongmei Ni, Shuting Liang, and Qianqian Li. "Experimental study on punching shear behavior of hollow floor slab-column reinforced connection." Advances in Structural Engineering 22, no. 7 (December 21, 2018): 1531–43. http://dx.doi.org/10.1177/1369433218819565.

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This article presents an experimental study on hollow floor slab-column-reinforced connections, which are enhanced by installing locally solid zone of slab around the column and hidden beam in the floor. To investigate the punching-shear behavior of hollow floor slab-column-reinforced connections, six hollow floor slab-column-reinforced connections under vertical load were conducted on three types of connections with different thickness, namely, two hollow floor slab-column-reinforced connections without punching component, two hollow floor slab-column-reinforced connections with bent-up steel bars, and two hollow floor slab-column-reinforced connections with welding section steel cross bridging. Meanwhile, the strength, stiffness, failure mode, and ductility of hollow floor slab-column-reinforced connections with punching components were obtained and compared with the hollow floor slab-column-reinforced connections without punching component. The results showed that hollow floor slab-column-reinforced connections had the double failure characteristics including punching shear and flexural failure, and flexural failure was the main failure mode as a result of installing hidden beam. The hollow floor slab-column-reinforced connections with punching components exhibited higher initial stiffness and higher loading capacity than hollow floor slab-column-reinforced connections without punching components, but welding section steel cross bridging have a better on improving the connections’ punching-shear capacity than bent-up steel bars.

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Kang, Tae Jin, Kyung Ho Jung, Jong Kyoo Park, Jae Ryoun Youn, and Seung Goo Lee. "Effect of Punching Density on the Mechanical and Thermal Properties of Needle-punched Nonwoven Carbon/Phenolic Composites." Polymers and Polymer Composites 10, no. 7 (October 2002): 521–30. http://dx.doi.org/10.1177/096739110201000704.

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The effects of changes in the fibre orientation on the mechanical properties of nonwoven composites were investigated through 3-point bending, short beam shear and tensile tests. Oxidized polyacrylonitrile(PAN) carded webs were needle-punched, and then carbonized to fabricate carbon composites with phenolic resin. The interlaminar shear, tensile and flexural strengths increased with increasing punching density. However, the rate of increase reduced and interlaminar shear and tensile strengths decreased with excessive punching density. The erosion rate and the insulation index were calculated by means of a torch test. The ablation resistance increased with increasing punching density, but no significant increase in the erosion rate with increasing punching density above 477 penetrations per square centimetre was found. The thermal conductivity of needle-punched nonwoven carbon/phenolic composites increased with increasing punching density.

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Salim, Muhamad Saifuddin, Z. A. Mohd Ishak, Dody Ariawan, and Mohd Zharif Ahmad Thirmizir. "Effect of Alkaline Treatment to Wettability and Flexural Properties of Kenaf Nonwoven Fibre Mat Reinforced Epoxy Composites Produced by Resin Transfer Moulding." Applied Mechanics and Materials 754-755 (April 2015): 99–105. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.99.

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This paper focuses on the study of the effect of chemical treatments of fibres by alkalization on the flexural and impact properties of epoxy matrix composites reinforced by kenaf fibre (KF) produced via resin transfer moulding (RTM) technique. The reinforcement consists of KF nonwoven fiber mat fabricated using needle punching method. Prior to punching process, KF are subjected to alkali treatments with Sodium hydroxide (NaOH) at 3, 6 and 9% for a period of 3h at room temperature. The composites were reinforced with kenaf nonwoven mat at 40% by volume. Effect of alkaline treatment concentration to wettability of KF towards epoxy resins are measured by means of contact angle and surface energy analysis. Influences of alkaline treatment on the flexural properties are studied to determine the optimum conditions of alkaline treatment. As concentration of NaOH in alkaline treatment increased, the experimental results show that the flexural properties of composites increases. For 6% NaOH treatment, the flexural strength and flexural modulus improved by 7.88 MPa to 81.38 Mpa and from 4.79 GPa to 5.41GPa compared to untreated fibre composites. However, as the concentration of NaOH increase to 9%, the bending properties reduced significantly.

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Xue, Hui Zhong, Hong Guan, and Yi Li. "Preliminary Collapse Simulation of a Reinforced Concrete Flat Plate Substructure Using Spring Connection Modelling." Applied Mechanics and Materials 638-640 (September 2014): 1445–48. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1445.

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To investigate progressive collapse behavior of reinforced concrete (RC) flat plate structures, a reliable and efficient numerical approach is developed in this study using spring connection modelling. This connection unit aims to simulate complicate punching shear behavior at critical regions surrounding the columns. Five springs are used as the connection elements: two for flexural and integrity steel bars and three for concrete contributions. The flexural and integrity steel bars embedded in the columns are modeled explicitly, which enables the model to present the structural behavior post punching shear failure. Bending and shear actions are represented by two concrete springs. The third concrete spring is assigned axial action property to restrain two end nodes of the connection on the model. In particular, the punching shear spring controls the connection unit when punching shear failure occurs. To apply the connection unit, the regions of slab-column connections are partitioned from the slab regions according to the critical shear surfaces. Then the connection unit links two corresponding nodes on the two edges formed from the partition. A physical experiment of a RC flat plate substructure under progressive collapse is simulated. Result comparison demonstrates that the numerical model has the capability to capture the structural behavior in progressive collapse. However, further improvement of the modelling technique is necessary to enhance numerical accuracy.

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Mufti, Aftab A., and Tarek K. Hassan. "Finite element analysis and theoretical study of punching shear strength of concrete bridge decks." Canadian Journal of Civil Engineering 32, no. 2 (April 1, 2005): 449–53. http://dx.doi.org/10.1139/l04-106.

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The problem of punching shear usually arises in reinforced concrete slabs subjected to concentrated loads and particularly in concrete bridge decks due to development of an internal arching system. Ongoing research revealed that the governing mode of failure of concrete bridge decks is not flexure and that using a flexural design method usually led to unnecessary high levels of steel reinforcement. This paper examines the applicability of nonlinear finite element formulation of restrained concrete bridge decks. A general purpose finite element program ANACAP was employed in this study. The accuracy of the nonlinear finite element analysis is demonstrated using test results conducted by other researchers. The results of the finite element analysis are also compared with those obtained from a rational model. The experimental results and the theoretical model provide insight to the fundamental behavior of concrete bridge decks.Key words: bridges, concrete, deflections, FRP, punching, reinforcement, slabs.

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Vainiūnas, Povilas, Vladimiras Popovas, and Andrei Jarmolajev. "PUNCHING SHEAR BEHAVIOUR ANALYSIS OF RC FLAT FLOOR SLAB-TO-COLUMN CONNECTION." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 8, no. 2 (June 30, 2002): 77–82. http://dx.doi.org/10.3846/13923730.2002.10531255.

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The paper presents information about theoretical investigations and based on computer modelling and analysis research methods of flat floor slab-to-column joint behaviour for punching” obtained by authors. Main principles of calculation and design methods of flat slab-to-column support under punching according to variety of international design coded are observed and compared. The design problems of beamless floor systems for shear with bending are discussed. The set of variables, such as lateral flexural reinforcement, bending moment to shear force ratio, span-to-slab depth ratio and slab thickness to column depth ratio, which may have an influence on flat two-ways floor slab punching shear strength is established and computer modelling analysis methods are applied to investigate the problem.

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Urban, Tadeusz, Łukasz Krawczyk, and Michał Gołdyn. "Experimental investigations of punching shear concrete slabs with different types of transverse reinforcement." Budownictwo i Architektura 13, no. 3 (September 11, 2014): 193–200. http://dx.doi.org/10.35784/bud-arch.1820.

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The results of support zone thick concrete slabs experimental investigation are presented in the paper. The experimental program consisted of 4 square reinforced concrete flat models to 1:2 scale made of the same concrete with the same dimensions and the same flexural reinforcement. The aim of tests was proved the influence of different transverse reinforcement types on punching shear load capacity. One of the models was a comparative slab made without transverse reinforcement. In the other slabs three types of transverse reinforcement were used: typical stirrups enclosing flexure reinforcement, stirrups situated between flexure reinforcement and ladders. The test results show a few percent difference in load capacity between models with transverse reinforcement, the most effective were typical stirrups enclosing the main reinforcement.

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Chen, Cheng-Chih, and Shun-Long Chen. "Strengthening of Reinforced Concrete Slab-Column Connections with Carbon Fiber Reinforced Polymer Laminates." Applied Sciences 10, no. 1 (December 30, 2019): 265. http://dx.doi.org/10.3390/app10010265.

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This study presents the structural behavior and punching shear strength of the concrete slab-column connections strengthened with carbon fiber reinforced polymer (CFRP) laminates. The variables considered for the twelve specimens included the compressive strength of the concrete, the ratio of the tensile steel reinforcement, and the amount of the CFRP laminates. Square concrete slabs were simply supported along four edges. During the test, monotonically concentrated load was applied to the stub column located at the center of the slab. The punching shear strength, stiffness, and mode of failure were investigated. Test results demonstrated that increasing the compressive strength of concrete, ratio of the steel reinforcement, and amount of the CFRP laminates led to an increase in the punching shear strength of the slabs. Moreover, the CFRP laminates were effective in appreciably increasing the punching shear strength of the slab-column connections. An analytical approach was conducted to calculate the punching shear strength of the slab-column connections strengthened with CFRP laminates. Based on the theory of reinforced concrete members, the application of the CFRP laminates increased the flexural strength of the slab and resulted in an increase of the effective depth of the slab section. Consequently, the punching shear strength was increased. The results of the analytical calculation revealed that the analytical work accurately predicted the experimental punching shear strength.

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Nováček, Jan, and Miloš Zich. "Study of Strengthening Flat Slabs against Punching by Additional Column Heads." Key Engineering Materials 691 (May 2016): 321–32. http://dx.doi.org/10.4028/www.scientific.net/kem.691.321.

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Over the past few years, punching shear has been in the forefront of both research teams and professional public due to a new approach to its verification according to Model Code 2010. From this topic, the task of flat slabs strengthening against punching shear has arisen. This problem, and in particular the problem of flat slabs strengthened by additional concrete column heads, is the focus of this paper. Structures are analysed using a 3D FEM models including material and geometric nonlinearity. The way of modelling is validated against experiments on non-strengthened flat slabs subjected to punching shear. At first, strengthening with a rigid connection at the interface between structures is considered and then, several different types of connection at the interface are evaluated. Finally, strengthening of structures with varying lengths of top flexural reinforcement in the slab is modelled while minimum anchorage length outside the additional column head is verified.

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Abdelkhalik, Amr, Tamer Elafandy, Amr Abdelrahman, and Alaa Sherif. "Tests of Slab-Column Connections Subjected to Reversed Cyclic Moments in Addition to Different Levels of Gravity Shear Load." Solid State Phenomena 292 (June 2019): 146–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.292.146.

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Reinforced concrete flat slab-column structures are widely used because of their practicality. However, this type of structures can be subjected to punching-shear failure within the slab-column connections. Without shear reinforcement, the slab-column connection can undergo brittle punching failure, especially when the structure is subjected to lateral loading in seismic zones. This research is a part of an extensive investigation about the punching shear behaviour of interior RC slab-column connections under seismic loading. The main objective is to discuss the effect of the gravity shear level on the punching shear behaviour[1].The current paper represents only the results of the first four tested specimens without shear reinforcement. The first specimen was tested subjected to vertical gravity load only without cyclic loading while the other three specimens were tested under different vertical loads V which was kept constant during testing in addition to a reversed displacement controlled cyclic loading which was increased up to punching shear failure. The gravity load V was chosen as 0.4, 0.6 and 0.8 V0 respectively, where V0 is the vertical load causing punching shear failure according to ACI318-14[2]. All tested specimens have the same slab dimensions of 2000x2000mm, slab thickness 200mm, flexural reinforcement ratio of 1.62% and the same column dimensions 250mm x 250mm. Finally, the experimental results are analyzed and compared to international codes such as American Code ACI318-14 and Euro Code EC2-2004[3]. In light of these results, some preliminary conclusions are presented.

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Kara, Ilker, and Besian Sinani. "Prediction of Punching Shear Capacity of Two-Ways FRP Reinforced Concrete Slabs." Spring 2017 5, no. 2 (May 1, 2017): 1–7. http://dx.doi.org/10.33107/ijbte.2017.5.2.03.

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An innovative solution to the corrosion problem is the use of fiber-reinforced polymer (FRP) as an alternative reinforcing material in concrete structures. In addition to the non corrodible nature of FRP materials, they also have a high strength-to-weight ratio that makes them attractive as reinforcement for concrete structures. Extensive research programs have been carried out to investigate the flexural behavior of concrete members reinforced with FRP reinforcement. On the other hand, the shear behavior of concrete members, especially punching shear of two-way slabs, reinforced with FRP bars has not yet been fully explored. The existing provisions for punching of slabs in most international design standards for reinforced concrete are based on tests of steel reinforced slabs. The elastic stiffness and bonding characteristics of FRP reinforcement are sufficiently different from those of steel to affect punching strength. In the present study, the equations of existing design standards for shear capacity of FRP reinforced concrete beams have been evaluated using the large database collected. The experimental punching shear strengths were compared with the available theoretical predictions, including the CSA S806 (CSA 2012), ACI-440.1R-15 (ACI 2015), BS 8110 (BSI 1997), JSCE (1997) a number of models proposed by some researchers in the literature. The existing design methods for FRP reinforced concrete slabs give conservative predictions for the specimens in the database. This paper also presents a simple yet improved model to calculate the punching shear capacity of FRPreinforced concrete slabs. The proposed model provides the accurate results in calculating the punching shear strengths of FRP-reinforced concrete slender slabs.

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Altaee, Malik K. E., and Jamal A. S. Khudair. "Punching Behavior Of Self-Compacting Concrete Slabs Incorporating Coarse Recycled Concrete Aggregates." Wasit Journal of Engineering Sciences 8, no. 1 (July 5, 2020): 1–11. http://dx.doi.org/10.31185/ejuow.vol8.iss1.147.

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This paper presents an experimental investigation on the effects of incorporating coarse recycled concrete aggregates (RCA) on the punching and flexural behaviour of reinforced concrete two-way slabs. For this purpose, four concrete mixes were designed with various substitution ratios of natural coarse aggregates (NCA) by RCA 0% (reference mix), 25, 50 and 75%. Subsequently, fourteen 800 × 800 mm × variable thickness reinforced concrete slabs (two per concrete type) were cast and subjected to punching and flexural tests. Different parameters that affect the behavior of two-way slabs were studied including type of failure, replacement ratios of NCA by RCA, amount of main reinforcement, thickness and loading patch size. In order to investigate the effect of RCA incorporation on hardened concrete properties (compressive strength Fcu, tensile Ft strength, flexural Fr strength and modulus of elasticity Ec), different replacement ratios were considered, while the quantity of cement was kept equaled for all the mixes (with and without RCA). Hardened concrete samples results showed that Fcu, Ft, Fr and Ec were decreased by (8.62, 13.54 and 19.12%), (13.08, 17.63 and 25.46%), (10.02, 21.67%, and 34.30%) and (9.69, 15.65 and 16.62%) respectively, for the (25, 50 and 75%) replacement ratios compared with samples made from SCC without RCA. The experimental results of slabs showed that the cracking and ultimate load (11% maximum reduction ratio) and moment (19.5% maximum reduction ratio) capacities of slabs were decreased compared with slabs made from SCC without RCA. Moreover, the load deflection curves were almost identical with proportional increase to the RCA content. From the general behavior, ultimate capacity, deflections, failure angle and crack pattern results, it can be concluded that the recycled concrete aggregate can be used as a partial replacement of natural coarse aggregate to produce self-compacting concrete mixes, where the behavior of two-way slabs cast with SCC containing RCA can considered acceptable.

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Fahmi Rasheed, Mereen H., and Ayad Z. Saber Agha. "Computational Analysis of Punching Shear Models of Steel Fiber Reinforced Concrete Slabs." Engineering and Technology Journal 38, no. 2A (February 25, 2020): 126–42. http://dx.doi.org/10.30684/etj.v38i2a.39.

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A computational analysis is presented to predict the ultimate and cracking shear strength of steel fiber reinforced concrete slabs. Different models are suggested considering the effect of concrete compressive and tensile strength, amount of flexural reinforcements, yield strength of the reinforcement bars and steel fiber properties (volume percent, aspect ratio, and type of steel fibers). The predicted results are compared with the experimental data found in literature and found good agreement.

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Cook, Wesley, Paul J. Barr, and Travis R. Brackus. "Flexural and Punching Shear Capacity Comparison of Full-Scale ABC Steel Bridge Girders." Journal of Performance of Constructed Facilities 29, no. 2 (April 2015): 04014054. http://dx.doi.org/10.1061/(asce)cf.1943-5509.0000545.

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Gnaba, Imen, Peng Wang, Damien Soulat, Fatma Omrani, Manuela Ferreira, and Philippe Vroman. "Investigation about the Effect of Manufacturing Parameters on the Mechanical Behaviour of Natural Fibre Nonwovens Reinforced Thermoplastic Composites." Materials 12, no. 16 (August 11, 2019): 2560. http://dx.doi.org/10.3390/ma12162560.

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To date, nonwoven fabrics made with natural fibres and thermoplastic commingled fibres have been extensively used in the composite industry for a wide variety of applications. This paper presents an innovative study about the effect of the manufacturing parameters on the mechanical behaviour of flax/PP nonwoven reinforced composites. The mechanical properties of nonwoven fabric reinforced composites are related directly to the ones of dry nonwoven reinforcements, which depend strongly on the nonwoven manufacturing parameters, such as the needle-punching and areal densities. Consequently, the influence of these manufacturing parameters will be analysed through the tensile and flexural properties. The results demonstrated that the more areal density the nonwoven fabric has, the more the mechanical behaviour can be tested for composites. By contrast, it has a complex influence on needle-punching density on the load-strain and bending behaviours at the composite scale.

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Oliveira, D. C., R. B. Gomes, and G. S. Melo. "Punching shear in reinforced concrete flat slabs with hole adjacent to the column and moment transfer." Revista IBRACON de Estruturas e Materiais 7, no. 3 (June 2014): 414–67. http://dx.doi.org/10.1590/s1983-41952014000300006.

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The structural behavior and the ultimate punching shear resistance of internal reinforced concrete flat slab-column connections, with one hole adjacent to the column, with or without flexural moment transfer of the slab to the column was investigated. Main variables were: the existence whether or not hole, flexural reinforcement layout and ratio, the direction and sense of the moment transferred and the eccentricity of the load (M (moment transferred to column) / V (shear)) ratio at the connection - 0,50 m or 0,25 m. Seven internal slab-column joining were tested and ultimate loads, cracking, deflections, concrete and reinforcement strains were analyzed. The existence of hole adjacent to the smaller column dimension, the hole dimension, flexural reinforcement rate and placing, the variation of relation Mu/Vu in function of the load, and, than, of eccentricity of the load, influenced the slabs behavior and rupture load. Test results were compared with the estimations from CEB-FIP/MC1990 [7], EC2/2004 [12], ACI-318:2011 [1] and NBR 6118:2007 [5]. ACI [1] and EC2 [12] presented most conservative estimates, although have presented some non conservative estimates. Brazilian NBR [5], even though being partly based in EC2 [12], presented smaller conservative estimates and more non conservative estimates. A modification on all codes is proposed for taking in account the moment caused by the eccentricity at the critical perimeter for slabs with holes.

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Salman, Donia, Rabab Allouzi, and Nasim Shatarat. "Punching shear behaviour of flat slabs with different reinforcement schemes: openings and rectangularity effects." International Journal of Structural Integrity 12, no. 4 (April 29, 2021): 589–612. http://dx.doi.org/10.1108/ijsi-08-2020-0079.

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PurposeThe main goal is to investigate the effect of size and location of opening and column size on the punching shear strength. Openings are often needed in order to install mechanical and electrical services. This process takes away part of the concrete volume which is responsible for resisting the shear forces and any unbalanced moment. Furthermore, the application of rectangular columns in flat slabs is commonly used in practice as they provide lateral stiffness to the building. They are also utilised in garages and multi-storey buildings where these elongated cross-sectional columns reduce the effective span length between adjacent columns.Design/methodology/approachThis research is a numerical-based investigation that is calibrated based on a thirteen previously tested and numerically calibrated slab specimens with no openings. A parametric study is conducted in this study to consider the effect of other parameters, which are the size and location of opening and the rectangularity ratio of column in order to evaluate their effect on the punching shear capacity. A total of 156 models are developed to study these factors. Additionally, the predicted shear carrying capacity of the simulated slabs is calculated using the ACI318–19 and Eurocode (EC2-04) equation.FindingsThe presence of openings reduced the punching shear capacity. The small opening's location and orientation have almost no effect except for one slab. For slabs of large openings, the presence of openings reduced the punching capacity. The punching capacity is higher when the openings are farther from the column. The numerically obtained results of slabs with rectangular columns show lower punching capacity compared to slabs of squared columns with the same length of the punching shear control perimeter. The punching capacity for all slabs is predicted by ACI318–19 and Eurocode (EC2-04) and it is found that Eurocode (EC2-04) provided a closer estimation.Originality/valueThe slabs considered for calibration were reinforced with four different punching shear reinforcement configurations, namely; ordinary closed rectangular stirrups, rectangular spiral stirrups, advanced rectangular spiral stirrups and circular spiral. Generally, there has been limited research on concrete flat slabs with openings in comparison with other subjects related to structural engineering (Guan, 2009) and no research on punching shear with openings of slabs reinforced with these reinforcement schemes. The available research focussed on the effects of openings on the flexural behaviour of reinforced concrete slabs includes Casadei et al. (2003), Banu et al. (2012) and Elsayed et al. (2009). In addition, experimental tests that examined slabs supported on rectangular columns are very limited.

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Ahmad, Hazrina, Mohd Hisbany Mohd Hashim, Afidah Abu Bakar, and Siti Hawa Hamzah. "Flexural behaviour and punching shear of selfcompacting concrete ribbed slab reinforced with steel fibres." MATEC Web of Conferences 138 (2017): 02010. http://dx.doi.org/10.1051/matecconf/201713802010.

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M. Kadhum, Mohammed, Salah M. Harbi, Shahad S. Khamees, Mustafa S. Abdulraheem, and Ehsan Noroozinejad Farsangi. "Punching Shear Behavior of Flat Slabs Utilizing Reactive Powder Concrete with and without Flexural Reinforcement." Practice Periodical on Structural Design and Construction 26, no. 1 (February 2021): 04020060. http://dx.doi.org/10.1061/(asce)sc.1943-5576.0000551.

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Mabrouk, Rasha T. S., Amr Bakr, and Hany Abdalla. "Effect of flexural and shear reinforcement on the punching behavior of reinforced concrete flat slabs." Alexandria Engineering Journal 56, no. 4 (December 2017): 591–99. http://dx.doi.org/10.1016/j.aej.2017.05.019.

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Qi, Jianan, Zhao Cheng, Kai Zhou, Yutong Zhu, Jingquan Wang, and Yi Bao. "Experimental and theoretical investigations of UHPC-NC composite slabs subjected to punching shear-flexural failure." Journal of Building Engineering 44 (December 2021): 102662. http://dx.doi.org/10.1016/j.jobe.2021.102662.

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Guan, Hong, and Yew-Chaye Loo. "Flexural and Shear Failure Analysis of Reinforced Concrete Slabs and Flat Plates." Advances in Structural Engineering 1, no. 1 (January 1997): 71–85. http://dx.doi.org/10.1177/136943329700100108.

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A nonlinear layered finite element procedure is presented for flexural and shear failure analysis of reinforced concrete slabs and flat plates. A degenerated shell element employing a layered discretization scheme is adopted. This provides a simple and effective means of accounting for the nonlinear behaviour of concrete and steel reinforcement over the thickness of the slab or flat plate. The procedure is capable of determining the load-deflection response, the ultimate load capacity and crack patterns of concrete slab structures, as well as computing the punching shear strength at slab-column connections of concrete flat plates. To verify the accuracy and reliability of the proposed method of analysis, comparative studies are carried out on a collection of reinforced concrete slabs, single slab-column connections and multi-column flat plates which were tested by other researchers. In general, good correlations are obtained with the published test results.

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Nishiyama, Misato, Pasha Javadi, Koki Maeda, and Tetsuo Yamakawa. "Experimental Investigations of RC Frames Retrofitted by Steel Braced Frames Using a New Hybrid Connection." Applied Mechanics and Materials 82 (July 2011): 594–99. http://dx.doi.org/10.4028/www.scientific.net/amm.82.594.

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In this paper, a new connection technique for installing steel braced frame inside an existing RC frame is proposed. The proposed connection, which is called “Hybrid Connection”, consists of high-strength grout, steel plates and high-strength bolts. In the current investigation, two fundamental modes, namely, Type I and Type II are experimentally verified. In the fundamental mode of Type I, the steel braces buckle and stretch, and the RC frame and the steel frame exhibit flexural behavior. In the fundamental mode of Type II, direct-shear failure happens in the hybrid connection at the beam connection, and punching (direct-shear) failure occurs at the top of RC columns.

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Daniel Ronald Joseph, J., J. Prabakar, and P. Alagusundaramoorthy. "Flexural behavior of precast concrete sandwich panels under different loading conditions such as punching and bending." Alexandria Engineering Journal 57, no. 1 (March 2018): 309–20. http://dx.doi.org/10.1016/j.aej.2016.11.016.

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Taib, Razaina Mat, Dody Ariawan, and Zainal Arifin Mohd Ishak. "Alkali Treatment of Kenaf Fiber Mat and its Influence on the Performance of Unsaturated Polyester/Kenaf Fiber Mat Composites." Advanced Materials Research 1024 (August 2014): 171–74. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.171.

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Non-woven kenaf fiber mats were prepared from untreated and alkali treated fibers by using a carding machine followed by needle punching. The alkali treatment was carried out by immersing the fiber mats in 6% NaOH solution for 0, 1, 2, 3, 4, and 5 h at room temperature. The untreated and alkali treated fiber mats were impregnated with unsaturated polyester resin via a resin transfer molding technique to form composites. Maximum improvements of flexural strength and flexural modulus of the composites were observed when the fiber mat was alkali treated for 3 h. The improved of both properties can be attributed to better fiber-matrix adhesion between the alkali treated kenaf fiber and the unsaturated polyester matrix most probably via mechanical interlocking. Water absorption tests were conducted by immersing the composite samples in distilled water at room temperature. The water absorption patterns of all the composites were found to follow Fickian behavior. The tendency of the composites to absorb water decreased when the alkali treated fiber mats were used.

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Choi, Kyoung-Kyu, Dong-Woo Shin, and Hong-Gun Park. "Modification of the ACI 318 Design Method for Slab-Column Connections Subjected to Unbalanced Moment." Advances in Structural Engineering 17, no. 10 (November 2014): 1469–80. http://dx.doi.org/10.1260/1369-4332.17.10.1469.

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In the ACI 318–11 design method for slab-column connections subjected to unbalanced moment, the contribution factors assigning the proportion of the connection unbalanced moment to be resisted by the slab flexural reinforcement and by eccentric vertical shear stresses are prescribed by only considering the aspect ratio of columns. However, the validity of the prescribed contribution factors have not been completely verified by extensive test results, and the strength prediction by the design method using the contribution factors does not agree well with existing test results. In the present study, a modified strength model was proposed without prescribing the contribution factors. In the proposed model, the contribution of flexural moment is directly calculated using the slab reinforcement ratio, and the contribution of eccentric shear is calculated based on the conventional eccentric shear stress model. The proposed method was verified by comparing its prediction with existing test results. The results showed that the proposed method predicts the test results with reasonable accuracy, and it corresponds with the fundamental mechanics of the punching shear of slab-column connections as investigated in previous studies.

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Xue, Jiang Wei, Yong Yang, Yi Zhao, and Xin Sheng Ge. "Three-Dimensional Analysis of the Partner of Laterally Loaded Variable Rigidity Pile (Pile Partner)." Applied Mechanics and Materials 256-259 (December 2012): 320–23. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.320.

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Concerning the stress and displacement of the partner under lateral load, reference on full-scale model tests on behavior of cast-in-place concrete pipe piles, two cases are analyzed by means of 3D finite element method, calculations show that in condition I, pile and cap rigid joint (pile foundation) plus partner, partner block the punching stress from pile top to cap continue to spread; and in condition II, the distance between pile top and pile cap is 200 mm, partner is in normal bending shear state; As the flexural rigidity of partner is much larger than the pile, if under earthquake or other rare action, partner may sacrifice firstly to keep pile perform well.

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潘, 立. "Checking Method Study of Punching Shear Capacity on the Flexural Crack Section in Concrete Slab-Column Joints." Hans Journal of Civil Engineering 09, no. 06 (2020): 587–93. http://dx.doi.org/10.12677/hjce.2020.96063.

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El-Salakawy, E. F., M. A. Polak, and M. H. Soliman. "Slab-column edge connections subjected to high moments." Canadian Journal of Civil Engineering 25, no. 3 (June 1, 1998): 526–38. http://dx.doi.org/10.1139/l97-117.

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This paper presents test results of eight large-scale reinforced concrete flat plate edge connections. The test specimens consisted of two identical series. Each series consisted of four specimens, two with openings, in the vicinity of the column, and the other two without openings. One of the specimens without an opening contained shear studs as shear reinforcement. The tests were designed to study the effect of high moment-to-shear ratio on the punching shear behaviour of the slab-column edge connections with openings. Each series was subjected to a different moment-to-shear ratio. The test parameters were the location of openings around the column, the shear reinforcement, and the moment-to-shear ratio. The openings in the specimens were square with the sides parallel to the sides of the column. The square dimension of the openings (150 × 150 mm) was 60% of the square column dimension. The slabs contained typical flexural reinforcement (ACI 318-95 and CSA A23.3-94) with the additional reinforcement added on the sides of the openings (equivalent to that interrupted by an opening). The design procedures in the Canadian and American codes (CSA A23.3-94 and ACI 318-95) are discussed and compared with the test results.Key words: columns, edge connections, flat concrete plates, punching shear, shear strength, high moments, openings, failure, shear reinforcement, reinforced concrete.

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Min, Kyung-Hwan, Hyun-Oh Shin, Doo-Yeol Yoo, and Young-Soo Yoon. "Flexural and Punching Behaviors of Concrete Strengthening with FRP Sheets and Steel Fibers under Low-Velocity Impact Loading." Journal of the Korea Concrete Institute 23, no. 1 (February 28, 2011): 31–38. http://dx.doi.org/10.4334/jkci.2011.23.1.031.

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Xiao, Bing, Yi Wan, Isamu Ohsawa, and Jun Takahashi. "Effect of needle punching on flexural behavior of carbon fiber-reinforced thermoplastic sandwich panel with spring-backed core." Composites Part A: Applied Science and Manufacturing 118 (March 2019): 57–66. http://dx.doi.org/10.1016/j.compositesa.2018.12.013.

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Mohamed, Osama Ahmed, Manish Kewalramani, and Rania Khattab. "Fiber Reinforced Polymer Laminates for Strengthening of RC Slabs against Punching Shear: A Review." Polymers 12, no. 3 (March 19, 2020): 685. http://dx.doi.org/10.3390/polym12030685.

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Reinforced concrete flat slabs or flat plates continue to be among the most popular floor systems due to speed of construction and inherent flexibility it offers in relation to locations of partitions. However, flat slab/plate floor systems that are deficient in two-way shear strength are susceptible to brittle failure at a slab–column junction that may propagate and lead to progressive collapse of a larger segment of the structural system. Deficiency in two-way shear strength may be due to design/construction errors, material under-strength, or overload. Fiber reinforced polymer (FRP) composite laminates in the form of sheets and/or strips are used in structurally deficient flat slab systems to enhance the two-way shear capacity, flexural strength, stiffness, and ductility. Glass FRP (GFRP) has been used successfully but carbon FRP (CFRP) sheets/strips/laminates are more commonly used as a practical alternative to other expensive and/or challenging methods such column enlargement. This article reviews the literature on the methodology and effectiveness of utilizing FRP sheets/strips and laminates at the column/slab intersection to enhance punching shear strength of flat slabs.

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Yooprasertchai, Ekkachai, Ratchanon Dithaem, Titi Arnamwong, Raktipong Sahamitmongkol, Jira Jadekittichoke, Panuwat Joyklad, and Qudeer Hussain. "Remediation of Punching Shear Failure Using Glass Fiber Reinforced Polymer (GFRP) Rods." Polymers 13, no. 14 (July 19, 2021): 2369. http://dx.doi.org/10.3390/polym13142369.

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The results of an experimental program on shear-strengthening of flat slabs using Glass Fiber Reinforced Polymer (GFRP) rods are presented. A total of seven specimens were tested under an upward concentric monotonic loading until failure. One specimen served as a control and was tested without any modification. The remaining six specimens were strengthened with post-installed GFRP rods in single (SG), double (DB), and radial (RD) patterns within shear critical parameters around the centric column. The results of this experimental study suggest that GFRP rods are capable of enhancing both the peak load and deformation capacity. Furthermore, brittle failure associated with punching shear failure was successfully avoided by all strengthening patterns. Of all of the patterns, the RD pattern resulted in maximum peak load increase and corresponding deformation capacity while the lowest bound was created by the SG pattern. The results suggested that SG, DB and RD patterns enhanced ultimate loads up to 9.1, 11.3 and 15.7% while corresponding deflections increased up to 109, 136 and 154%. Strain measurement on flexural reinforcement suggested that all strengthened specimens were able to withstand higher longitudinal strains than yield. It was further shown that reducing the spacing between the GFRP rods efficiently enhanced peak loads, nevertheless, neither this change was proportional, nor did it result in an enhanced energy dissipation capacity. In the end, recommendations of American Concrete Institute (ACI) for the shear strength of two-way systems were modified to incorporate the contributions from GFRP rods. The results indicate that the proposed analytical approach provides an excellent match with the experimental results.

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Xie, Qun, Song Xue, Zhen-hua Liang, and Ming-qiang Lin. "Experimental investigation of prefabricated steel-truss waffle slab under flexural loading." Advances in Structural Engineering 23, no. 2 (August 14, 2019): 263–76. http://dx.doi.org/10.1177/1369433219868928.

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A novel type of prefabricated steel-truss waffle slab has been proposed in this article, and compared with traditional waffle slab, there are several typical characteristics of this floor system, including welded steel wire mesh laid in top concrete wythe, orthogonal steel trusses used to reinforce concrete ribs, and foamed concrete blocks filled among the ribs with the purpose of heat insulation and fire resistance. A special template system is adopted for the installation and concrete cast of prefabricated steel-truss waffle slab. All steel segments in prefabricated steel-truss waffle slab are precast and then assembled to form steel system in site. In order to investigate the structural behavior of prefabricated steel-truss waffle slab, two full-scale specimens with different aspect ratio have been experimentally studied under flexural load. The results obtained from the tests have been discussed and analyzed in the context of ultimate flexural load, cracking pattern and failure mode, load–deflection relationship, and load–strain relationship. The experimental results showed that the ultimate load-bearing capacity of prefabricated steel-truss waffle slab has greatly been influenced by the punching shear failure at the rib joints. Three crack types, such as flexural cracks, tensile cracks, and interface cracks, have been exhibited in the final failure of prefabricated steel-truss waffle slab. The deflection development at slab center has presented a four-stage behavior. The significant effect of aspect ratio has also been verified by strain analysis. A computer program has been developed according to the modified structural design method proposed in this article, and the comparison indicated a good agreement between experimental data and theoretical results.

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El-Salakawy, Ehab F., Maria Anna Polak, and Monir H. Soliman. "Reinforced concrete slab-column edge connections with shear studs." Canadian Journal of Civil Engineering 27, no. 2 (April 1, 2000): 338–48. http://dx.doi.org/10.1139/l99-062.

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The paper reports the results of an experimental investigation on the influence of shear studs on the behaviour of reinforced concrete slab-column edge connections with openings. The test parameters were the location of openings around the column, the size of openings, and the existence of shear reinforcement. The objective of the paper is to present and discuss the results of large-scale tests on slabs with shear stud reinforcement and compare these test results with those of tests on identical slabs but without shear reinforcement. All tested slabs contained same amounts of typical flexural reinforcement (ACI 318-95 and CSA A23.3-94). The presented test results can be used for studying the behaviour of slab-column connections and for calibration of the predictive models.Key words: reinforced concrete, edge connections, flat concrete plates, punching shear, shear strength, openings, failure, shear studs, shear reinforcement.

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Salem, Adel H., Mohamed A. El-Aghoury, Ezzeldin Y. Sayed-Ahmed, and Tarek S. Moustafa. "Composite steel-free deck bridges: Numerical modelling and pilot parametric study." Canadian Journal of Civil Engineering 29, no. 5 (October 1, 2002): 662–78. http://dx.doi.org/10.1139/l02-060.

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During the past decade, composite steel-free deck bridges came to reality in Canada through the construction of five bridges. The new structural system enables the construction of a concrete deck that is totally devoid of all internal steel reinforcement. Traditionally, reinforced concrete bridge decks are designed to sustain loads in flexure. The steel-free deck bridge system develops internal compressive forces "internal arching," which leads to failure by punching shear at substantially higher loads than the flexural design load. The fibre-reinforced concrete deck is usually attached to the steel girders through flexible shear connectors. These steel girders are transversely tied together by steel straps and cross frames. In this paper, the concept of the new bridge system is briefly discussed. The generations of the deck slabs are introduced. Brief outlines of the bridges built to date with this new technology are presented. A three-dimensional finite element model is then proposed to study the behaviour of the main structural component of the new system. The model is verified against previous experimental results and is used to perform a parametric study on some aspects which are thought to significantly affect the behaviour of the new steel-free deck bridge system.Key words: bridges, composite girders, finite element method, steel-free deck, steel straps.

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Barros, Joaquim A. O., Mohammadali Rezazadeh, João P. S. Laranjeira, Mohammad R. M. Hosseini, Mohammad Mastali, and Honeyeh Ramezansefat. "Simultaneous flexural and punching strengthening of RC slabs according to a new hybrid technique using U-shape CFRP laminates." Composite Structures 159 (January 2017): 600–614. http://dx.doi.org/10.1016/j.compstruct.2016.10.009.

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Elmoussa, Baraa, Yehya Temsah, and Ali Jahami. "Numerical study for the effect of hairpin shaped shear reinforcement on one-way shear capacity of reinforced concrete beams." MATEC Web of Conferences 281 (2019): 01015. http://dx.doi.org/10.1051/matecconf/201928101015.

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This study investigates the effectiveness of using Hairpin shaped stirrups to increase the shear capacity of beams and slabs. The hairpin system consists of inverted U-shape stirrups welded to flexural corner rebar. Previous research works proved the increase of the hairpin system in increasing the two-way shear capacity compared to conventional punching reinforcement. However, the system’s ability to increase the shear capacity of beams has not been explored. This paper presents the results of Finite Element simulation of two beams performed using ABAQUS Software; one beam is reinforced with conventional shear stirrups, and the other is reinforced with hairpin stirrups. The load capacity, deflection and damage pattern of the two beams were compared. Results showed that beams reinforced with hairpin stirrups have higher load capacity and ductility compared to beams with conventional stirrups. However, the reinforcement type had little effect on the shear damage pattern.

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Kadlec, Lukáš, and Vladimir Červenka. "Model Uncertainties of FEM Nonlinear Analyses of Concrete Structures." Solid State Phenomena 249 (April 2016): 197–202. http://dx.doi.org/10.4028/www.scientific.net/ssp.249.197.

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Advanced numerical simulations are more often used due to the increasing possibilities of computer technology. For material descriptions, generally nonlinear constitutive relations are employed. It is expected that in the near future the reliability of structures will be assessed by use of these sophisticated calculations. For this purpose, it is firstly necessary to evaluate the model uncertainty of the numerical model, because the structural reliability is directly affected by the model uncertainty. Recommended values of model uncertainties differ in individual scientific literary sources. In standard codes the partial safety factor for model uncertainty is set by relatively low value. This value was assessed by empirical way and it seems that such value is valid only for flexural failure. Contemporary numerical simulations indicate larger model uncertainties. Moreover, the value of model uncertainty should be related to particular failure mode. This paper presents a comprehensive procedure for the determination of model uncertainties of nonlinear analyses. In the second part, the value of model uncertainties is derived for punching of slabs.

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Ghannoum, M. A., L. Long, N. Isham, A. Bulgheroni, M. Setaro, M. Caserini, R. Palmieri, and F. Mailland. "Ability of Hydroxypropyl Chitosan Nail Lacquer To Protect against Dermatophyte Nail Infection." Antimicrobial Agents and Chemotherapy 59, no. 4 (December 29, 2014): 1844–48. http://dx.doi.org/10.1128/aac.04842-14.

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ABSTRACTThe development of a topical agent that would strengthen the nail, improve the natural barrier, and provide better drug penetration to the nail bed is needed. In this study, we examined the effects of a hydroxypropyl chitosan (HPCH)-based nail solution using a bovine hoof model. Following application of the nail solution, changes in the hardness of the hoof samples were measured using the Vickers method. Tensile and flexural strengths were tested by stretching or punching the samples, respectively. The ultrastructure was examined using scanning electron microscopy (SEM), and samples stained with periodic acid-Schiff (PAS) stain were used to determine the fungal penetration depth. The comparators included 40% urea and 70% isopropyl alcohol solutions. The HPCH nail solution increased hoof sample hardness in comparison to the untreated control sample (mean, 22.3 versus 19.4 Vickers pyramid number [HV]). Similarly, the HPCH solution increased the tensile strength (mean, 33.07 versus 28.42 MPa) and flexural strength (mean, 183.79 versus 181.20 MPa) compared to the untreated control. In contrast, the comparators had adverse effects on hardness and strength. SEM showed that the HPCH solution reduced the area of sample crumbling following abrasion compared to the untreated control (7,418 versus 17,843 pixels), and the PAS-stained images showed that the HPCH solution reduced penetration of the dermatophyte hyphae (e.g., penetration byTrichophyton mentagrophyteswas <25 μm at day 9 versus 275 μm in the untreated control). Unlike chemicals normally used in cosmetic treatments, repeated application of the HPCH nail solution may help prevent the establishment of new or recurring fungal nail infection.

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Nelson, Mark, and Amir Fam. "Modeling of Flexural Behavior and Punching Shear of Concrete Bridge Decks with FRP Stay-in-Place Forms Using the Theory of Plates." Journal of Engineering Mechanics 140, no. 12 (December 2014): 04014095. http://dx.doi.org/10.1061/(asce)em.1943-7889.0000813.

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El-Gendy, Mohammed, and Ehab El-Salakawy. "Effect of flexural reinforcement type and ratio on the punching behavior of RC slab-column edge connections subjected to reversed-cyclic lateral loads." Engineering Structures 200 (December 2019): 109703. http://dx.doi.org/10.1016/j.engstruct.2019.109703.

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Bakht, Baidar, and Akhilesh C. Agarwal. "Deck slabs of skew girder bridges." Canadian Journal of Civil Engineering 22, no. 3 (June 1, 1995): 514–23. http://dx.doi.org/10.1139/l95-060.

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Canadian codes allow the design of concrete deck slabs of slab-on-girder bridges by taking account of the internal arching action that develops in these slabs under concentrated wheel loads in particular. Provided that certain prescribed conditions are met, a deck slab is deemed to have met the design criteria if it is provided with a top and a bottom layer of steel reinforcement with each layer consisting of an orthogonal mesh of steel bars in which the area of cross section of the bars in each direction is at least 0.3% of the effective area of cross section of the deck slab. For deck slabs of bridges having skew angles greater than 20°, the codes require the minimum amount of reinforcement to be doubled in the end zones near the skew supports. Model testing has shown that need for such an increase can be eliminated by providing composite end diaphragms with high flexural rigidity in the horizontal plane. The proposed concept is tested on a model of fibre-reinforced concrete deck without steel reinforcement in which deficiencies in the confinement of the deck slab readily manifest themselves in form of a bending, rather than punching shear, failure. Key words: highway bridges, bridge decks, deck slabs, skew deck, skew bridges, fibre-reinforced concrete decks.

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Buttignol, T. E. T., J. L. A. O. Sousa, and T. N. Bittencourt. "Ultra High-Performance Fiber-Reinforced Concrete (UHPFRC): a review of material properties and design procedures." Revista IBRACON de Estruturas e Materiais 10, no. 4 (August 2017): 957–71. http://dx.doi.org/10.1590/s1983-41952017000400011.

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ABSTRACT This paper does a review of the recent achievements on the knowledge of UHPFRC properties and in the development of design procedures. UHPFRC is defined as a new material, with unique properties (high ductility, low permeability, very high strength capacity in compression, higher toughness) in comparison to conventional concrete. It is important to know both material and mechanical properties to fully take advantage of its outstanding properties for structural applications. However, since this is a new material, the current design codes are not well suited and should be reviewed before being applied to UHPFRC. In the first part, the following material properties are addressed: hydration process; permeability; fibers role; mix design; fiber-matrix bond properties workability; mixing procedure; and curing. In the second part, the mechanical properties of the material are discussed, together with some design recommendations. The aspects herein examined are: size effect; compressive and flexural strength; tensile stress-strain relation; shear and punching shear capacity; creep and shrinkage; fracture energy; steel bars anchorage and adherence. Besides, the tensile mechanical characterization is described using inverse analysis based on bending tests data. In the last part, material behavior at high temperature is discussed, including physical-chemical transformations of the concrete, spalling effect, and transient creep. In the latter case, a new Load Induced Thermal Strain (LITS) semi-empirical model is described and compared with UHPC experimental results.

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Gu, Qian, Cheng Fang Sun, and Shao Min Peng. "Experimental Study on Deep Four-Pile Caps with Different Reinforcement Layouts Based on 3D Strut-and-Tie Analogy." Key Engineering Materials 400-402 (October 2008): 917–22. http://dx.doi.org/10.4028/www.scientific.net/kem.400-402.917.

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Based on 3D strut-and-tie analogy developed for analyzing the load-transferring mechanism of deep pile cap, this paper focuses on the effect of different longitudinal reinforcement layouts at the lower part of cap on the mechanical behaviors of deep four-pile cap. Besides a common layout of uniformly distributed reinforcement by the flexural theory, three different layouts of concentrated reinforcement over piles were designed by 3D strut-and-tie analogy. All specimens were limited in same reinforcement percentages, dimensions, materials and test procedures. Four specimens with the scale ratio of 1/5 were tested under the statically incremental gravity loading. The load capacity, deflection, strain of longitudinal reinforcement of specimens were measured, and the failure mode, crack propagation, deformation of specimens and stress distribution of reinforcement were analyzed. Through comparisons of the test results among all specimens, it was found that deep pile cap failed in shear and corner-pile punching whether with concentrated or uniform reinforcement, and the reinforcement concentrated over each two adjacent piles, similar to the tension bars in the strut-and-tie model, had considerable advantages than common uniform reinforcement layout. The ultimate strength of deep pile cap with concentrated reinforcement was significantly increased, while the improvement of deformation resistance and brittleness of deep pile cap was limited. According to above findings, the appropriate reinforcement layouts for deep pile cap were suggested in this paper.

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Han, Eui-Seok, Junho Gong, Dooyong Cho, and Sun-Kyu Park. "Experimental Investigation on the Application of Ultra-Rapid-Hardening Mortar for Rigid Small Element Pavement." Advances in Materials Science and Engineering 2019 (June 23, 2019): 1–9. http://dx.doi.org/10.1155/2019/2625437.

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Natural stones have been typically used as a paving material in historically conserved areas due to architectural aesthetic aspect and environmental impact. However, they have been traditionally suggested in light traffic volume due to the defects caused by the increased traffic loading and volume. The failures can lead to diverse problems such as losing flatness, severe damage to both vehicles and pedestrians, high traffic congestion, maintenance cost, etc. In order to overcome these obstacles, ultra-rapid-hardening (URH) cement for rigid small element pavement (SEP) was implemented as both jointing and laying course materials. Additionally, their mechanical properties were investigated according to BS 7533-4 and National Stone Surface (NSS) in the UK. Preliminarily, the proper mix mortar design was found by comparing design parameters. The compressive and flexural strength of the joint and laying course by age was verified, and the results in early-age stage were satisfied with the requirements. The adhesive and shear strengths depending upon the width of the joint were determined, and from the test outcomes, the optimal thickness of the joint was found as 15 mm. Furthermore, by contrasting the compressive strength of the laying course with the punching shear strength, the shear strength regarding joint states was increased by up to 134.3% (fully restrained), 127.9% (semirestrained), and 107.2% (non restrained). This investigation would be possible to use as baseline data for an evaluation of the long-term performance of rigid SEP.

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Freitas de Almeida, Iago, Maurício Castelo Branco de Noronha Campos, and Romilde Almeida de Oliveira. "A comparative study in flexure and shear design of spread footings." Revista Ingenio 16, no. 1 (January 1, 2019): 23–29. http://dx.doi.org/10.22463/2011642x.2364.

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The design of spread footings is a field widely explored in structural engineering being the flexure and shear design verified by the use of codes. The objective of this paper consists in a comparative study of spread footing design between the Brazilian’s code, Eurocode and American’s code. The methodology considered an analytical analysis with three different examples in the flexure and shear design of the spread footings with different loads and footing height. The results show that the American’s code presented the minimum required value of reinforcement rates in all examples and also was the only code that verified the punching and shear effect for all studied cases. In Eurocode flexure design, the results show that in the most examples, the reinforcement rate is higher than that considered by the other codes. The Brazilian code presented an inconsistency in the verification of the punching effect for one of the studied examples, requiring, therefore, a review and a modification of the code.

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Ghali, Amin, and Adel A. Elgabry. "Moment and shear transfer between columns and concrete slabs." Canadian Journal of Civil Engineering 17, no. 4 (August 1, 1990): 621–28. http://dx.doi.org/10.1139/l90-070.

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Gravity and horizontal forces cause the transfer of vertical shear and moments between concrete flat slabs and their supporting columns. These forces can cause punching failure. Design equations for safety against punching given in the Canadian Standards Association and the American Concrete Institute codes are critically reviewed. It is shown that the equations give in some cases incorrect stresses which do not satisfy equilibrium. A modification is suggested which makes the equations applicable to all cases. The paper also discusses the codes' approach of sharing the resistance to transferred moment between resistances by flexure and by eccentricity of shear, using the coefficient γv. Comparisons are made with the result of finite element analyses. It is concluded that the code equations, with the suggested modification, are adequate, provided that appropriate values are used for the coefficient γv. Key words: columns, connections, flat concrete plates, moments, punching shear, reinforced concrete, shear strength, slabs, structural design.

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Journal articles on the topic 'Flexural punching'

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