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1
Parker, Daniel Edward. "Shear strength within reinforced concrete beam-column joints." Thesis, University of Bolton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492666.
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Reinforced concrete is an economical construction material and is widely used throughout the world in buildings and bridges. The shear strength within beam-column joints in reinforced concrete structures has been identified as an area where further research is still needed in order to form reliable design methods. The aim of this research programme has been to develop a rational analytical model which can be used conveniently in the design of beam-column joints. The work consists of a brief literature review, an extensive experimental programme and the development of a new analytical model for predicting the strength of beam-column joints. The new analytical model is a development of the strut-and-tie model and is believed to be original in two ways: (a) The influence of the shear span and the spacing of the links (if any) are considered directly. (b) The inclination of the compression field is determined by maximising the contribution of the concrete to the stiffness of the member in shear. The new analytical model is shown to predict the strength of the test specimens and of many specimens reported in the literature more reliably than current design codes and standards
2
Ridwan. "Reinforced concrete beam-column joints strengthened in shear with embedded bars." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/7138/.
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Beam-column (BC) joints play an important role in the seismic performance of moment-resisting reinforced concrete (RC) frame structures. Without adequate joint shear reinforcement, BC joints can be the most vulnerable elements during an earthquake. Several techniques for improving the seismic performance of BC joints have been proposed, but they have been criticised for being labour-intensive and/or susceptible to premature debonding. This research explores the application of the deep embedment technique for strengthening a shear-deficient beam-column joint. Two approaches, experimental and finite element (FE) study were conducted. The experiment contained the tests of seven exterior RC BC joints under constant column axial load and a reverse cyclic load at the beam end. Variables considered during the experiments were the material type and embedded reinforcement ratio. The FE study included the modelling of the tested specimens using ABAQUS and parametric study to asses the effect of column axial load, concrete compressive strength and embedded bar size on joint shear strength. The experimental results showed the strengthened specimens had superior global and local behaviour compared to the control one. In addition, the maximum joint shear strength also changes linearly with the variation of the concrete strength, column axial load and embedded bar size.
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Fisher, Matthew John. "Experimental Evaluation of Reinforcement Methods for Concrete Beam-Column Joints." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243628129.
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Byrne, Joseph D. R. "Bond and shear mechanics within reinforced concrete beam-column joints incorporating the slotted beam detail." Thesis, University of Canterbury. Civil & Natural Resources Engineering, 2012. http://hdl.handle.net/10092/8716.
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The recent earthquakes in Christchurch have made it clear that issues exist with current RC frame design in New Zealand. In particular, beam elongation in RC frame buildings was widespread and resulted in numerous buildings being rendered irreparable. Design solutions to overcome this problem are clearly needed, and the slotted beam is one such solution. This system has a distinct advantage over other damage avoidance design systems in that it can be constructed using current industry techniques and conventional reinforcing steel. As the name suggests, the slotted beam incorporates a vertical slot along part of the beam depth at the beam-column interface. Geometric beam elongation is accommodated via opening and closing of these slots during seismically induced rotations, while the top concrete hinge is heavily reinforced to prevent material inelastic elongation.
Past research on slotted beams has shown that the bond demand on the bottom longitudinal reinforcement is increased compared with equivalent monolithic systems. Satisfying this increased bond demand through conventional means may yield impractical and economically less viable column dimensions. The same research also indicated that the joint shear mechanism was different to that observed within monolithic joints and that additional horizontal reinforcement was required as a result.
Through a combination of theoretical investigation, forensic analysis, and database study, this research addresses the above issues and develops design guidelines. The use of supplementary vertical joint stirrups was investigated as a means of improving bond performance without the need for non-standard reinforcing steel or other hardware. These design guidelines were then validated experimentally with the testing of two 80% scale beam-column sub-assemblies. The revised provisions for bond within the bottom longitudinal reinforcement were found to be adequate while the top longitudinal reinforcement remained nominally elastic throughout both tests. An alternate mechanism was found to govern joint shear behaviour, removing the need for additional horizontal joint reinforcement. Current NZS3101:2006 joint shear reinforcement provisions were found to be more than adequate given the typically larger column depths required rendering the strut mechanism more effective.
The test results were then used to further refine design recommendations for practicing engineers. Finally, conclusions and future research requirements were outlined.
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Wong, Ho Fai. "Shear strength and seismic performance of non-seismically designed reinforced concrete beam-column joints /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20WONG.
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Deaton, James B. "Nonlinear finite element analysis of reinforced concrete exterior beam-column joints with nonseismic detailing." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47538.
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This research investigated the behavior of nonseismically detailed reinforced concrete exterior beam-column joints subjected to bidirectional lateral cyclic loading using nonlinear finite element analysis (NLFEA).
Beam-column joints constitute a critical component in the load path of reinforced concrete buildings due to their fundamental role in integrating the overall structural system. Earthquake reconnaissance reports reveal that failure of joints has contributed to partial or complete collapse of reinforced concrete buildings designed without consideration for large lateral loads, resulting in significant economic impact and loss of life. Such infrastructure exists throughout seismically active regions worldwide, and the large-scale risk associated with such deficiencies is not fully known. Computational strategies provide a useful complement to the existing experimental literature on joint behavior and are needed to more fully characterize the failure processes in seismically deficient beam-column joints subjected to realistic failure conditions. Prior to this study, vulnerable reinforced concrete corner beam-column joints including the slab had not been analyzed using nonlinear finite element analysis and compared with experimental results.
The first part of this research focused on identification and validation of a constitutive modeling strategy capable of simulating the behaviors known to dominate failure of beam-column joints under cyclic lateral load using NLFEA. This prototype model was formulated by combining a rotating smeared crack concrete constitutive model with a reinforcing bar plasticity model and nonlinear bond-slip formulation. This model was systematically validated against experimental data, and parametric studies were conducted to determine the sensitivity of the response to various material properties. The prototype model was then used to simulate the cyclic response of four seismically deficient beam-column joints which had been previously evaluated experimentally. The simulated joints included: a one-way exterior joint, a two-way beam-column exterior corner joint, and a series of two-way beam-column-slab exterior corner joints with varying degrees of seismic vulnerability. The two-way corner joint specimens were evaluated under simultaneous cyclic bidirectional lateral and cyclic column axial loading. For each specimen, the ability of the prototype model to capture the strength, stiffness degradation, energy dissipation, joint shear strength, and progressive failure mechanisms (e.g. cracking) was demonstrated.
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Unal, Mehmet. "Analytical Modeling Of Reinforced Concrete Beam-to-column Connections." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612230/index.pdf.
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Prior studies indicated that beam-to-column connections of reinforced concrete (RC) moment resisting frame structures experience considerable deformations under earthquake loading and these deformations have a major contribution to story drift of the building. In current analysis and design applications, however, the connection regions are generally modeled as rigid zones and the inelastic behavior of the joint is not taken into account. This assumption gives rise to an underestimation of the story drifts and hence to an improper assessment of the seismic performance of the structure. In order to implement the effect of these regions into the seismic design and analysis of buildings, a model that properly represents the seismic behavior of connection regions needs to be developed. In this study, a parametric model which predicts the joint shear strength versus strain relationship is generated by investigating the several prior experimental studies on RC beam-to-column connections subjected to cyclic loading and establishing an extensive database. Considering previous experimental research and employing statistical correlation method, parameters that significantly influence the joint behavior are determined and these parameters are combined together to form a joint model. This model is then verified by comparing the results obtained from the dynamic earthquake analysis by Perform 3D with the experimental ones. The main contribution of the developed model is taking into account parameters like the effect of eccentricity, column axial load, slab, wide beams and transverse beams on the seismic behavior of the connection region, besides the key parameters such as concrete compressive strength, reinforcement yield strength, joint width and joint transverse reinforcement ratio.
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Liu, Cong. "Seismic behaviour of beam-column joint subassemblies reinforced with steel fibres." Thesis, University of Canterbury. Civil Engineering, 2006. http://hdl.handle.net/10092/1118.
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High performance cementitious composites have been increasingly used for a range of structural applications in many countries. More recently, a notable interest has been focused on structural performance under seismic loading. However, a critical lack of coherent information and experimental/numerical data available in the literature has to be recognized along with the absence of specific and well-accepted code-guidelines for use of FRC in seismic applications. More specifically, when dealing with seismic resistant frame systems, few researchers have investigated in the past the seismic response of beam-column joints reinforced with steel fibres. These preliminary experimental tests have shown that adding steel fibres in joints is an effective method for improving joint behaviour and energy absorption capacity as well as enhancing the damage tolerance of joints and reducing the number of stirrups in seismic joints. However, due to the limited number of experimental tests as well as of the wide dispersion in the type and mechanical properties of the fibres adopted in these independent researches, the actual contributions of concrete, steel fibres and stirrups to the overall joint shear capacity has not yet been clearly identified and understood. This research aims to investigate the seismic behaviour and failure modes of beam-column joint subassemblies reinforced with steel fibres with the intent to provide preliminary suggestions for a simple but rational analytical procedure to evaluate the joint shear strength when either fibres and/or stirrups are adopted. As part of a more comprehensive on-going research campaign on the seismic behaviour of FRC members and systems, six 2-D exterior beam-column joint subassemblies were tested under simulated seismic loading (quasi-static cyclic loading regime) at the Civil Engineering Laboratory of the University of Canterbury. In order to assess the contribution of steel fibres to the joint (panel zone) shear strength, both under-designed systems (with no transverse reinforcement in the joint, following older practice before the pre-1970s) and well designed systems (following the NZ concrete design standard NZS 3101:1995) were adopted as benchmark specimens. The performance of steel fibre reinforced beam-column joints were compared with that of conventional joints. Results showed that using steel fibre reinforced concrete (SFRC) within beam-column joints can significantly enhance the shear resistance capacity of joints. However, using steel fibre reinforcement alone can not prevent buckling of the reinforcing bars when joints are under high intensity seismic loading. Furthermore, the test results also showed that using steel fibre reinforcement is an effective method to reduce the lateral reinforcement in the beam plastic hinge region. As part of the analytical investigation, a simplified procedure to evaluate the joint shear contribution provided by different amounts of fibres with or without the presence of stirrups has been also introduced. Influence of the axial load on the joint nominal shear capacity has been accounted for by adopting principle stresses. Tentative strength degradation curves (principle tensile stress vs. shear deformation) have also been calibrated on the experimental data which confirmed that a tentative relationship between the joint shear contributions provided by concrete, stirrups and steel fibres was a viable tool for designing SFRC joint. Furthermore, joint shear resistance coefficient contributed by steel fibres has been compared with previous experimental test available in literature to obtain an appropriate value for SFRC joint design guidelines. M_N performance based domain visualization has also been used to evaluate the hierarchy of strength and sequence of events of beam-column joint subassemblies.
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SILVA, RAQUEL ALVES CABRAL. "THEORETICAL AND EXPERIMENTAL ANALYSIS OF A COMPOSITE SEMI-RIGID BEAM-TO-COLUMN JOINT USING PERFOBOND SHEAR CONNECTORS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27553@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Nos projetos de engenharia é comum desconsiderar-se o comportamento semirrígido das ligações, ou seja, as ligações são assumidas com as condições ideais de rigidez. A primeira condição ideal é aquela na qual há transferência total de momento fletor, assumindo-se que não existe rotação relativa entre os elementos ligados, estas ligações são as chamadas rígidas. Na segunda opção, a transferência de momento fletor é desconsiderada e a ligação é definida como rotulada ou simples. Entretanto, sabe-se que a maioria das ligações comporta-se como semirrígida e o problema é que ao se fazer essas simplificações em projeto, dois aspectos podem ser comprometidos: segurança estrutural e custo do projeto. Neste trabalho, uma ligação semirrígida mista é proposta e estudada com o objetivo de obter-se as suas características principais e necessárias para utilizá-la em projeto: curva momento-rotação, rigidez de serviço e momento fletor resistente. Com a ligação mista proposta, busca-se uma nova maneira de transferência de forças na região de momento negativo em uma viga semicontínua. Adotou-se para a transferência dos esforços, entre a laje de concreto e a viga de aço, conectores de cisalhamento do tipo Perfobond Rib. Este conector foi inicialmente utilizado em pontes e depois alguns estudos o viabilizaram para o uso em edificações. Para atingir os objetivos do trabalho, foram realizados dois ensaios em escala real das ligações propostas. Os testes experimentais foram feitos em modelos cruciformes invertidos e realizados no laboratório de estruturas e materiais da PUC-Rio. Os resultados experimentais foram comparados com dois modelos analíticos: o método proposto por Leon et al. em 1996 e o método presente no Anexo R da NBR 8800:2008.
In engineering design it is common to disregard the semi-rigid behavior of connections, i.e., connections are assumed to have the ideal conditions of rigidity. The first ideal condition is the one in which there is full transfer of bending moment, assuming that there is no relative rotation between the connected elements, this connection is defined rigid. In the second option, the transfer of bending moment is disregarded and the connection is defined simple. However, it is known that most connections have a semi-rigid behavior and the problem is that when making these simplifications in design, two aspects can be compromised: structural safety and project cost. In this work, a composite semi-rigid connection is studied in order to obtain its main and necessary features to use it in design: moment-rotation curve, service rigidity and bending moment capacity. With the proposed composite connection, a new way to transfer forces in the negative moment region on a semicontinous beam. Shear connectors like the Perfobond Rib were adopted for the transfer of efforts between the concrete slab and the steel beam. This connector was first used on bridges and since then some studies have made possible its use in buildings, showing its advantages over the more usual connectors. To achieve this work s objectives, two real scale tests of the proposed connections were conducted. Experimental tests were done in inverted cruciform models and carried out in the laboratory of structures and materials at PUC-Rio. Information on these tests was obtained, such as displacements, strains, and cracking of the slab. The experimental results were compared to two analytical models: the method proposed by Leon et al. in 1996 and the present method in Annex R of NBR 8800: 2008.
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Guan, Youliang. "Crack path selection and shear toughening effects due to mixed mode loading and varied surface properties in beam-like adhesively bonded joints." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/24905.
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Structural adhesives are widely used with great success, and yet occasional failures can occur, often resulting from improper bonding procedures or joint design, overload or other detrimental service situations, or in response to a variety of environmental challenges. In these situations, cracks can start within the adhesive layer or debonds can initiate near an interface. The paths taken by propagating cracks can affect the resistance to failure and the subsequent service lives of the bonded structures. The behavior of propagating cracks in adhesive joints remains of interest, including when some critical environments, complicated loading modes, or uncertainties in material/interfacial properties are involved. From a mechanics perspective, areas of current interest include understanding the growth of damage and cracks, loading rate dependency of crack propagation, and the effect of mixed mode fracture loading scenarios on crack path selection. This dissertation involves analytical, numerical, and experimental evaluations of crack propagation in several adhesive joint configurations. The main objective is an investigation of crack path selection in adhesively bonded joints, focusing on in-plane fracture behavior (mode I, mode II, and their combination) of bonded joints with uniform bonding, and those with locally weakened interfaces.
When removing cured components from molds, interfacial debonds can sometimes initiate and propagate along both mold surfaces, resulting in the molded product partially bridging between the two molds and potentially being damaged or torn. Debonds from both adherends can sometimes occur in weak adhesive bonds as well, potentially altering the apparent fracture behavior. To avoid or control these multiple interfacial debonding, more understanding of these processes is required. An analytical model of 2D parallel bridging was developed and the interactions of interfacial debonds were investigated using Euler-Bernoulli beam theory. The numerical solutions to the analytical results described the propagation processes with multiple debonds, and demonstrated some common phenomena in several different joints corresponding to double cantilever beam configurations. The analytical approach and results obtained could prove useful in extensions to understanding and controlling debonding in such situations and optimization of loading scenarios.
Numerical capabilities for predicting crack propagation, confirmed by experimental results, were initially evaluated for crack behavior in monolithic materials, which is also of interest in engineering design. Several test cases were devised for modified forms of monolithic compact tension specimens (CT) were developed. An asymmetric variant of the CT configuration, in which the initial crack was shifted to two thirds of the total height, was tested experimentally and numerically simulated in ABAQUS®, with good agreement. Similar studies of elongated CT specimens with different specimen lengths also revealed good agreement, using the same material properties and cohesive zone model (CZM) parameters. The critical specimen length when the crack propagation pattern abruptly switches was experimentally measured and accurately predicted, building confidence in the subsequent studies where the numerical method was applied to bonded joints.
In adhesively bonded joints, crack propagation and joint failure can potentially result from or involve interactions of a growing crack with a partially weakened interface, so numerical simulations were initiated to investigate such scenarios using ABAQUS®. Two different cohesive zone models (CZMs) are applied in these simulations: cohesive elements for strong and weak interfaces, and the extended finite element method (XFEM) for cracks propagating within the adhesive layer. When the main crack approaches a locally weakened interface, interfacial damage can occur, allowing for additional interfacial compliance and inducing shear stresses within the adhesive layer that direct the growing crack toward the weak interface. The maximum traction of the interfacial CZM appears to be the controlling parameter. Fracture energy of the weakened interface is shown to be of secondary importance, though can affect the results when particularly small (e.g. 1% that of the bulk adhesive). The length of the weakened interface also has some influence on the crack path. Under globally mixed mode loadings, the competition between the loading and the weakened interface affects the shear stress distribution and thus changes the crack path. Mixed mode loading in the opposite direction of the weakened interface is able to drive the crack away from the weakened interface, suggesting potential means to avoid failure within these regions or to design joints that fail in a particular manner.
In addition to the analytical and numerical studies of crack path selection in adhesively bonded joints, experimental investigations are also performed. A dual actuator load frame (DALF) is used to test beam-like bonded joints in various mode mixity angles. Constant mode mixity angle tracking, as well as other versatile loading functions, are developed in LabVIEW® for use with a new controller system. The DALF is calibrated to minimize errors when calculating the compliance of beam-like bonded joints. After the corrections, the resulting fracture energies ( ) values are considered to be more accurate in representing the energy released in the crack propagation processes. Double cantilever beam (DCB) bonded joints consisting of 6061-T6 aluminum adherends bonded with commercial epoxy adhesives (J-B Weld, or LORD 320/322) are tested on the DALF. Profiles of the values for different constant mode mixity angles, as well as for continuously increasing mode mixity angle, are plotted to illustrate the behavior of the crack in these bonded joints.
Finally, crack path selection in DCB specimens with one of the bonding surfaces weakened was studied experimentally, and rate-dependency of the crack path selection was found. Several contamination schemes are attempted, involving of graphite flakes, silicone tapes, or silane treatments on the aluminum oxide interfaces. In all these cases, tests involving more rapid crack propagation resulted in interfacial failures at the weakened areas, while slower tests showed cohesive failure throughout. One possible explanation of this phenomenon is presented using the rate-dependency of the yield stress (commonly considered to be corresponding to the maximum traction) of the epoxy adhesives. These experimental observations may have some potential applications tailoring adhesive joint configurations and interface variability to achieve or avoid particular failure modes.Ph. D.
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Semendary, Ali A. "Behavior of Adjacent Prestressed Concrete Box Beam Bridges Containing Ultra High Performance Concrete (UHPC) Longitudinal Joints." Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1518181442348314.
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Silva, Matheus Fernandes de Araújo. "Desenvolvimento de modelo analítico para determinação da resistência ao cisalhamento de nós de pórtico externos de concreto armado." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-30072013-093003/.
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Propõe-se um modelo analítico para determinação da resistência ao cisalhamento de nós de pórtico externos em estruturas de concreto armado. Faz-se um estudo de modelos analíticos propostos por pesquisadores e sua aplicação em uma extensa base de dados com resultados experimentais de diferentes ligações, a fim de verificar a eficiência de cada modelo analítico. Em paralelo realiza-se uma análise paramétrica por meio de simulação numérica utilizando o software DIANA® de maneira a compreender o comportamento do nó externo analisando a influência da geometria, nível de tensões no pilar, taxa de armadura da viga e taxa de estribos, e assim propõe-se um modelo de cálculo para a resistência ao cisalhamento com base nos resultados desta análise paramétrica. Por fim o modelo analítico proposto é aplicado na base de dados apresentando bons resultados e comprovando sua eficácia tanto para nós de pórtico externos sem estribo como com estribos.A proposal of an analytical model for determining the shear strength of exterior reinforced concrete beam-column joints is made in this work. A study of analytical models proposed by researchers and their application in a wide database with experimental results is done in order to verify the effectiveness of each analytical model. In parallel a parametric analysis by numerical simulation using the software DIANA® is performed in order to understand the behavior of the joint by analyzing the influence of the geometry, stress level in the column, longitudinal reinforcement ratio of beam and stirrup ratio and thus, it is proposed a model for predicting the shear strength based on the results of this parametric analysis. Finally the analytical design model proposed is applied to the database and presents good results proving its effectiveness for both external joint with and without stirrups.
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El-Amoury, Tarek Abbas Ghobarah Ahmed. "Seismic rehabilitation of concrete frame beam-column joints /." *McMaster only, 2004.
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Islam, Mohammad Majharul. "Global-local Finite Element Fracture Analysis of Curvilinearly Stiffened Panels and Adhesive Joints." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/38687.
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Global-local finite element analyses were used to study the damage tolerance of curvilinearly stiffened panels; fabricated using the modern additive manufacturing process, the so-called unitized structures, and that of adhesive joints. A damage tolerance study of the unitized structures requires cracks to be defined in the vicinity of the critical stress zone. With the damage tolerance study of unitized structures as the focus, responses of curvilinearly stiffened panels to the combined shear and compression loadings were studied for different stiffenersâ height. It was observed that the magnitude of the minimum principal stress in the panel was larger than the magnitudes of the maximum principal and von Mises stresses. It was also observed that the critical buckling load factor increased significantly with the increase of stiffenersâ height.
To study the damage tolerance of curvilinearly stiffened panels, in the first step, buckling analysis of panels was performed to determine whether panels satisfied the buckling constraint. In the second step, stress distributions of the panel were analyzed to determine the location of the critical stress under the combined shear and compression loadings. Then, the fracture analysis of the curvilinearly stiffened panel with a crack of size 1.45 mm defined at the location of the critical stress, which was the common location with the maximum magnitude of the principal stresses and von Mises stress, was performed under combined shear and tensile loadings. This crack size was used because of the requirement of a sufficiently small crack, if the crack is in the vicinity of any stress raiser. A mesh sensitivity analysis was performed to validate the choice of the mesh density near the crack tip. All analyses were performed using global-local finite element method using MSC. Marc, and global finite element methods using MSC. Marc and ABAQUS. Negligible difference in results and 94% saving in the CPU time was achieved using the global-local finite element method over the global finite element method by using a mesh density of 8.4 element/mm ahead of the crack tip. To study the influence of different loads on basic modes of fracture, the shear and normal (tensile) loads were varied differently. It was observed that the case with the fixed shear load but variable normal loads and the case with the fixed normal load but variable shear loads were Mode-I. Under the maximum combined loading condition, the largest effective stress intensity factor was very smaller than the critical stress intensity factor. Therefore, considering the critical stress intensity factor of the panel with the crack of size 1.45 mm, the design of the stiffened panel was an optimum design satisfying damage tolerance constraints.
To acquire the trends in stress intensity factors for different crack lengths under different loadings, fracture analyses of curvilinearly stiffened panels with different crack lengths were performed by using a global-local finite element method under three different load cases: a) a shear load, b) a normal load, and c) a combined shear and normal loads. It was observed that 85% data storage space and the same amount in CPU time requirement could be saved using global-local finite element method compared to the standard global finite element analysis. It was also observed that the fracture mode in panels with different crack lengths was essentially Mode-I under the normal load case; Mode-II under the shear load case; and again Mode-I under the combined load case. Under the combined loading condition, the largest effective stress intensity factor of the panel with a crack of recommended size, if the crack is not in the vicinity of any stress raiser, was very smaller than the critical stress intensity factor.
This work also includes the performance evaluation of adhesive joints of two different materials. This research was motivated by our experience of an adhesive joint failure on a test-fixture that we used to experimentally validate the design of stiffened panels under a compression-shear load. In the test-fixture, steel tabs were adhesively bonded to an aluminum panel and this adhesive joint debonded before design loads on the test panel were fully applied. Therefore, the requirement of studying behavior of adhesive joints for assembling dissimilar materials was found to be necessary. To determine the failure load responsible for debonding of adhesive joints of two dissimilar materials, stress distributions in adhesive joints of the nonlinear finite element model of the test-fixture were studied under a gradually increasing compression-shear load. Since the design of the combined load test fixture was for transferring the in-plane shear and compression loads to the panel, in-plane loads might have been responsible for the debonding of the steel tabs, which was similar to the results obtained from the nonlinear finite element analysis of the combined load test fixture.
Then, fundamental studies were performed on the three-dimensional finite element models of adhesive lap joints and the Asymmetric Double Cantilever Beam (ADCB) joints for shear and peel deformations subjected to a loading similar to the in-plane loading conditions in the test-fixtures. The analysis was performed using ABAQUS, and the cohesive zone modeling was used to study the debonding growth. It was observed that the stronger adhesive joints could be obtained using the tougher adhesive and thicker adherends. The effect of end constraints on the fracture resistance of the ADCB specimen under compression was also investigated. The numerical observations showed that the delamination for the fixed end ADCB joints was more gradual than for the free end ADCB joints.
Finally, both the crack propagation and the characteristics of adhesive joints were studied using a global-local finite element method. Three cases were studied using the proposed global-local finite element method: a) adhesively bonded Double Cantilever Beam (DCB), b) an adhesive lap joint, and c) a three-point bending test specimen. Using global-local methods, in a crack propagation problem of an adhesively bonded DCB, more than 80% data storage space and more than 65% CPU time requirement could be saved. In the adhesive lap joints, around 70% data storage space and 70% CPU time requirement could be saved using the global-local method. For the three-point bending test specimen case, more than 90% for both data storage space and CPU time requirement could be saved using the global-local method.Ph. D.
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Salisbury, Seth T. "Repair and strengthening of reinforced concrete beam-column joints." Connect to resource, 2010. http://hdl.handle.net/1811/45377.
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Motamed, Jubin. "Monolithic beam to external column joints in reinforced concrete." Thesis, University of Westminster, 2010. https://westminsterresearch.westminster.ac.uk/item/90727/monolithic-beam-to-external-column-joints-in-reinforced-concrete.
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The benefits of high strength concrete (HSC) in the construction of multi-storey buildings are commonly acknowledged. Past researchers have investigated the suitability of design codes for the use of HSC [1]. However, there are concerns about the shear behaviour of HSC beams and BCJ used in the construction of these buildings. HSC beams have equal or less shear resistance compared to normal strength concrete (NSC) beams [2], and the brittleness of HSC material could be unsuitable for BCJ as confinement stirrups may not be as effective as NSC in the column due to a smaller Poisson’s ratio. This research investigates the behaviour of HSC beams, BCJ and transfer beam column joints (TBCJ), and develop appropriate design modifications to improve their shear capacity. HSC beams were strengthened with horizontal web bars (HWB), while TBCJ were strengthened with central vertical bars (CVB). Finite element (FE) models were developed for these structures and the numerical results were compared with those of the published experimental results, concluding that good agreement had been achieved. Beam span/depth (a/d) ratio of 1.5≤a/d ≤3.02 and BCJ of beam to column depth ( db/dc ) ratio of 1.33 ≤ db/dc ≤3.1 were analysed. The FE models were compared with published test results and further ones were developed to carry out various parametric investigations. Struts and ties were mechanically modelled for beams with HWB and for TBCJ with CVB are used to recommend design equation modifications for the design of HSC beams with HWB and TBCJ with CVB. It was found that HWB and CVB are effective in beams and BCJ only with HSC as they have little influence when they were used with NSC. Using HWB in HSC beams and CVB in HSC TBCJ improved the shear capacity of these structures by 130% and 31% respectively. 1 - Regan, P. E., Kennedy -Reid I. L., Pullen, A. D., Smith, D. A. ‘The influence of aggregate type on the shear resistance of reinforced concrete’ – The Structural Engineer. 6 December 2005. p 27-32. 2 - Al-Hussaini, A. Motamed, J. ‘HSC beams with combination of links and horizontal web steel as alternative shear reinforcement’. 6th International Symposium on Utilization of High Strength/High Performance Concrete, Leipzig, June 2002. p 611- 619
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Jemaa, Yaser. "Seismic behaviour of deficient exterior RC beam-column joints." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/15025/.
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Post-earthquake reconnaissance and results of previously conducted experiments show that stiffness and strength deterioration of beam-column joints can have a detrimental effect on the integrity and vulnerability of reinforced concrete frame structures, especially in older buildings in developing countries. As a result, there is a need to develop efficient structural evaluation techniques that are capable of accurately estimating the strength and deformability of existing buildings to facilitate the development of safer, simpler, and lower cost retrofit solutions and thus contributing to risk mitigation. The current research is part of a general effort that is being carried out at the University of Sheffield to quantify and develop strategies for the mitigation of seismic risk in developing countries. The primary aim of this work is to improve the current understanding of the seismic behaviour of deficient exterior reinforce concrete beam-column joints. Seven full-scale isolated exterior beam-column joints were tested under quasi-static cyclic loading to investigate and quantify the effects of using different types of beam reinforcement anchorages and low column axial loads on the seismic shear performance of exterior beam-column joints with no shear reinforcement. Contrary to what is reported in the literature, the test results show that increasing the column axial load even at very low levels «O.2f'oAg,) can enhance the joint shear strength of deficient exterior joints (exhibiting pure shear failure) by up to 15%. The test results also show that, for the same joint panel geometry and column axial load, the type of beam anchorage detail, whether it is a straight bar, long or short hook, can influence the joint shear strength by up to 34%. A new analytical model that predicts the shear strength of deficient exterior beam-column joints in both loading directions and takes into account the column axial load and bond conditions within the joint is developed. The model predicts with good accuracy the strength of the tested specimens in addition to other specimens reported by other researchers. Furthermore, a springbased exterior beam-column joint model for finite element analysis of deficient RC frames is proposed. The model development includes a joint shear stress-strain constitutive model based on the developed strength model. The simulated response using the proposed model shows good agreement with the experimentally observed response.
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Vollum, Robert Lars. "Design and analysis of reinforced concrete beam-column joints." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/7500.
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Hannah, Mark Alexander. "Investigation of the design recommendations of reinforced concrete beam-column joints." Thesis, University of Canterbury. Civil Engineering, 2013. http://hdl.handle.net/10092/10981.
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A parametric analysis on 58 beam-column joint specimens has been conducted. The analysis considered 14 fundamental parameters in the design of each specimen and two performance indicators: the horizontal shear strength ratio between the maximum measured strength and the theoretical strength at beam yield, and the nominal curvature ductility of the adjacent beams. Each parameter was varied by a power function, while the linear correlation coefficient between each parameter and performance indicator was recorded. A combined multiple parameter analysis was then conducted to show the interaction of the design parameters and show the representative influences of each parameter based on the magnitude of the applied power functions.
Two design equations were constructed from the most influential design parameters, one for each performance indicator. The shear strength ratio was found to be governed by the horizontal joint shear stress, the column axial stress and the yield strength of the longitudinal beam reinforcement. The available curvature ductility of the adjacent beams was also found to be governed by the horizontal joint shear stress, the column axial stress and the yield strength of the longitudinal beam reinforcement, but also the quantity of the horizontal joint shear reinforcement.
The influence of the column axial stress on both performance indicators was found to be best represented by a quadratic function. This was because the column axial stress was found to be beneficial up to stress levels of , but axial stress levels exceeding were found to be detrimental to the performance of the beam-column joint, compared to a joint with no axial stress on the columns. The non-linear relationship of the column axial stress agreed with the design assumptions in NZS 3101 for low axial stress values, but at higher axial stress values NZS 3101 assumes a continued performance increase as a result of increasing axial stress, which has been found to be un-conservative. Additionally, an interaction between the column axial stress and the horizontal joint shear stress has been identified. As a result, beam-column joints with high column axial stress levels above 0.40 and horizontal joint shear stress levels in the order of have been shown to fail in a brittle crushing of the concrete in the joint core. Considering this behaviour, it is recommended that the column axial stress levels in earthquake designed beam-column joints should not exceed 0.35 .
The results of the parametric analysis were then compared against the current NZS 3101 design equations for conservatism. It was found that a reduction in the horizontal joint shear reinforcement may be possible for beam-column joints incorporating Grade 300 steel in the longitudinal reinforcement of the beams and axial stress levels below 0.25 , but when Grade 500 steel is used or the column axial stress is greater than 0.25 , an increase in the joint shear reinforcement is required compared to NZS 3101. The current NZS 3101 design requirement of at least 40% of the joint shear force, to be resisted by means of joint shear reinforcement, has been found to be appropriate.
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Leong, Mun-Foo. "MOMENT-ROTATION CHARACTERISTICS OF BEAM-TO-COLUMN CONNECTIONS." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275028.
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MEIRA, MAGNUS THIAGO DA ROCHA. "EXPERIMENTAL STUDY OF BEAM-COLUMN JOINTS WITH DIFFERENT CONCRETE STRENGTHS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15357@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O emprego de concretos de diferentes resistências em pilares e nos demais elementos do edifício, sendo o concreto dos pilares o de maior resistência, tem sido uma opção adotada em algumas edificações. Nas construções em geral, o concreto do pavimento é colocado continuamente atravessando o nó pilar-pavimento. Como resultado, o concreto da parte do pilar na região de encontro entre o pavimento e o pilar tem uma resistência menor do que no resto do pilar. Como, em geral, esta região do pilar se encontra confinada pelo pavimento, surge então a dúvida sobre qual é a resistência à compressão que se deve utilizar no cálculo do pilar; se deve ser a do pilar, a do pavimento ou um valor intermediário. O objetivo do trabalho é estudar experimentalmente a influência do confinamento do nó em pilares interceptados por vigas. As variáveis adotadas foram a taxa de armadura e a deformação específica inicial na armadura longitudinal das vigas. Nesta tese foram estudados experimentalmente quatro espécimes com vigas nas duas direções e oito espécimes com vigas em uma direção. Também foram ensaiados dois pilares isolados e homogêneos, um com concreto de mesma resistência à compressão do concreto utilizado no pilar e outro com concreto com resistência igual à resistência do concreto das vigas. As resistências nominais dos concretos das vigas e dos pilares foram 30 MPa e 70 MPa respectivamente. Os resultados indicaram que o confinamento promovido por vigas nas duas direções resulta num aumento significativo na carga de ruptura. O aumento da taxa de armadura das vigas aumenta a capacidade final somente nos espécimes com vigas nas duas direções. A influência da deformação inicial na armadura das vigas é inexpressiva.
The use of concretes with different strengths in columns and in the others elements of the floor, with the columns having the concrete with the highest strength, has been an option adopted in some buildings. In general, the concrete of the floor is poured continuously crossing the floor-column joint. As a result, the concrete strength in the joint region is lower than the concrete strength of the rest of the column. Since, in general, the joint region is confined by the floor, a doubt on the effective strength of the joint remains. The objective of the present work was to study experimentally the influence of the lateral confinement in the joint region of columns intercepted by beams. The variables were the reinforcement ratio and the initial strain in the tension reinforcement of the beams. In the present thesis, four specimens with beams in one direction and eight specimens with beams in two directions were studied experimentally. In addition, two isolated columns were also tested, one with concrete of same strength of the concrete of the columns and other with concrete of same strength of the concrete of the beams. The compressive concrete strength of the beams and columns were 30 MPa and 70 MPa respectively. The results indicated that the confinement provided by beams in two directions causes a significant increase of the failure load. The increase of the tension reinforcement ratio of the beams increases the failure load only in specimens with beams in two directions. The initial strain in the tension reinforcement of the beams has no effect on the ultimate capacity of the specimens.
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Elflah, Mohamed A. Hussaen. "Structural behaviour of stainless steel bolted beam to column joints." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8545/.
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Initially, two experimental programmes studying the structural behaviour of stainless steel beam-to-open column joints and beam-to-tubular column joints under static loads are reported in detail. The joint configurations tested include flush and extended end plate connections, top and seat cleat connections and top, seat and web cleat connections. The full moment-rotation characteristics are reported in detail. It is observed that the connections displayed excellent ductility, superior than that of equivalent carbon steel connections, and attained loads much higher than the ones predicted by design standards for carbon steel joints. Nonlinear FE models have been developed and validated against the experimental results. The FE models are shown to accurately replicate the experimentally determined, initial stiffness, ultimate resistance, overall moment-rotation response and observed failure modes. In addition, a comprehensive parametric study is conducted. The design rules for stainless steel connections, which are based on the specifications of EN 1993-1-8 for carbon steel joints, are reviewed and are found to be overly conservative in terms of strength and inaccurate in terms of stiffness thus necessitating the development of novel design guidance in line with the observed structural response. Hence, simplified mechanical models in line with the observed response are developed.
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Cheung, (Patrick) Pak Chiu. "Seismic design of reinforced concrete beam-column joints with floor slab." Thesis, University of Canterbury. Civil Engineering, 1991. http://hdl.handle.net/10092/9451.
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Beam-column joints are addressed in the context of current design procedures and performance criteria for reinforced concrete ductile frames subjected to large earthquake motions. Attention is drawn to the significant differences between the pertinent requirements of concrete design codes of New Zealand and the United States for such joints. The difference between codes stimulated researchers and structural engineers of the United States, New Zealand, Japan and China to undertake an international collaborative research project. The major investigators of the project selected issues and set guidelines for co-ordinated testing of joint specimens designed according to the codes of the countries. The tests conducted at the University of Canterbury, New Zealand, are reported. Three full-scale beam-column-slab joint assemblies were designed according to existing code requirements of NZS 3101:1982, representing an interior joint of a one-way frame, an interior joint of a two-way frame, and an exterior joint of a two-way frame. Quasistatic cyclic loading simulating severe earthquake actions was applied. The overall performance of each test assembly was found to be satisfactory in terms of stiffness, strength and ductility. The joint and column remained essentially undamaged while plastic hinges formed in the beams. The weak beam-strong column behaviour sought in the design, desirable in tall ductile frames designed for earthquake resistance, was therefore achieved. Using the laws of statics and test observations, the action and flow of forces from the slabs, beams and column to the joint cores are explored. The effects of bond performance and the seismic shear resistance of the joints, based on some postulated mechanisms, are examined. Implications of the test results on code specifications are discussed and design recomendations are made.
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Smallidge, Jeffrey M. "Behavior of bolted beam-to-column T-stub connections under cyclic loading." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19534.
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Birss, B. R. "The elastic behaviour of earthquake resistant reinforced concrete interior beam-column joints." Thesis, University of Canterbury. Civil Engineering, 2013. http://hdl.handle.net/10092/7750.
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This report is concerned with the theoretical and experimental study of the behaviour of interior reinforced concrete beam-column joints under simulated earthquake loading.
An experimental program investigated the performance of two beam-column joint subassemblages subjected to static cyclic loading within elastic limits. The post-elastic behaviour of the two test units was then examined by testing to failure.
A theoretical method for analysis of the joint shear resisting mechanisms is reviewed and analyses of prototype beam-column joints are reported. Results of this analysis were then compared with those obtained from the test units. The design method is shown to provide a satisfactory and conservative estimate of the joint shear reinforcement required in an elastic beam-column joint.
The failure of the joints in the test units verified the expectations that their response to inelastic seismic load demands would have been unsatisfactory.
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Thaker, Tariq Ali. "Experimental and nonlinear finite element analysis of double skin beam-column joints." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16042/.
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The Double Skin Composite (DSC) or Steel-Concrete-Steel (SCS) elements (beams, slabs and columns) have been subjected to intensive studies during the last three decades. Member beam, column and slab have been studied under monotonic, cyclic and fatigue loading, and there are also a few studies on impact loading to assess the structural response of such constructions. Validating connectivity between the DSC beam and DSC columns is behind the usage of such constructional systems since all the present studies focus on individual members. The main objective of this thesis was to introduce the Double Skin Composite (DSC) beam-column joint as a new structural element. Experimental investigation and Nonlinear Finite Element Modelling (FEM) of the structural behaviour of the DSC joint subjected to monotonic and quasi-static loading was introduced. Five DSC joints have been tested to assess the efficiency of the DSC beam-column joint in its basic design and to identify the most efficient strengthening method. Further, six DSC beam-column joints were tested to study the effect of steel fibre (SF) and the effect of high-strength concrete (HSC) on the behaviour of the joint under monotonic loading and under cyclic loading. The general FE Package ABAQUS 6.10 was used to model the nonlinear behaviour of the DSC joint. The Concrete Damage Plasticity Model (CDPM) was used to model the concrete in tension and compression, and the steel elements of the composite were modelled using the elastic-plastic model. The model was validated against the experimental result and showed good agreement in predicting the maximum load and the general behaviour with a deviation of 10% or less. The examined strengthening methods showed improvement in the ultimate load capacity of between 517% and 871%. SFC and HSC provided the best performance in increasing the ultimate load and moving the location of the plastic hinge away from the face of the column. The validated FE model was used to conduct a parametric study to investigate the effect of the concrete compressive strength, shear stud connector spacing to steel plate thickness ratio, and the stud diameter to steel plate thickness ratio. The parametric study findings were in good agreement with experimental observations such as that the concrete compressive strength had a significant effect on the joint shear resistance and ultimate load.
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Pohoryles, D. A. "Realistic FRP seismic strengthening schemes for interior reinforced concrete beam-column joints." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1553180/.
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The observation, in recent earthquakes, of brittle collapses of reinforced concrete (RC) structures built before the introduction of detailed seismic design codes (pre-1970’s), underlines the need for significant upgrades to the existing RC building stock. In particular, weak-column/strong-beam mechanisms and shear failures have potentially catastrophic impacts that could be addressed by repair and retrofit solutions. In recent years, retrofits with fibre reinforced polymers (FRP) are becoming increasingly popular due to the benefits of corrosion resistance, high strength-to-weight ratio and reduced labour time. Experimental evidence for the efficiency of such schemes for joint strengthening can be found in the literature. An analysis of all available literature shows that the reduced scale of most tested specimens, as well as the omission of slabs and transverse beams in many studies, may lead to an unrealistic assessment of FRP retrofit schemes. In this study, pre-1970’s full-scale interior beam-column joints with slab and transverse beams are hence tested under realistic conditions in order to propose and assess new and practical FRP retrofit solutions for seismic actions. Three carbon FRP (CFRP) retrofit schemes with selective retrofit objectives are designed using outcomes from the literature and from calibrated finite-element models. The retrofit schemes are composed of a combination of FRP strengthening and selective weakening components to ensure failure of inadequately reinforced RC beam-column joints according to capacity design principles. The objectives of the schemes include the enhancement in lateral capacity and ductility, as well as changing the failure mechanism of the joint. Results from full-scale cyclic tests on the CFRP retrofitted specimens are compared to the behaviour of a deficient specimen and a specimen designed to modern guidelines (EC8), highlighting the successful achievement of the respective retrofit objectives. To evaluate the effect of the realistic set-up, the results are also compared to specimens without slab and transverse beams, highlighting their importance. Finally, new design equations, to be used in conjunction with existing guidelines, are formulated to ease the practical adoption of the proposed retrofit scheme.
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Rifai, Abdussalam Mahmud. "Behaviour of columns in sub-frames with semi-rigid joints." Thesis, University of Sheffield, 1987. http://etheses.whiterose.ac.uk/3050/.
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The behaviour of limited subassemblages with flexible beans and semi-rigid beam to column connections was studied using a computer program in which the finite element method was employed in a non-linear analysis which accounts for the presence of semi-rigid connections and the inelastic behaviour of frames. The program accounts for many other factors such as initial imperfections and residual stresses. The theoretical background to the present computer program has been presented along with the program layout. The program was used to simulate some of the experimental results obtained from tests on rigidly and flexibly connected frames with different combinations of beam and column loads. The analytical results were found to compare reasonably well with the experimental results. The program was also used to simulate a series of I-shaped subassemblages that were tested at the University of Sheffield. Comparisons were made between the analytical and experimental results characterized by the maximum loads, load-deflection curves and load- moment curves. Good agreement was obtained between the analytical and the experimental load-deflection curves for all of the cases considered. The general trends of the measured and calculated load- moment curves for most cases were found to be comparable. The recommendations given in B35950 for the design of columns in simple construction were applied to all cases in the last series and were found unconservative in the cases of balanced loading and conservative in the cases of unbalanced loads. A limited parametric study was conducted to study the effects of semi-rigid joints, bean flexibility and type of loading. In this study, an I-shaped subassemblage was analysed for different load types and different types of beam to column connections. A substantial effect was recognized due to the presence of semi-rigid connections whether or not a beam load was applied. Beam flexibility was also seen to affect the carrying capacity of the subassemblage under the action of column load only although this effect was less noticeable than that of the connection flexibility. The presence of beam load was found to result in an unexpected interaction curve which relates the total force in the column to the moment that is transmitted to the column's end. An almost linear relationship with negative gradient seems to exist between the column and beam loads. It is pointed out that all the findings of the present study are based on the range of cases considered in the parametric study but it is suggested that they serve as indicators to the behaviour of any the subassemblage under axial load oniy or axial load combined with beam loads. A few recommendations for future work are presented.
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黃崑 and Kun Huang. "Design and detailing of diagonally reinforced interior beam-column joints for moderate seismicity regions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244233.
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Islam, Mohammad Aminul. "Constitutive modeling and plastic analysis with application to beam-to-column connections." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184486.
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Analysis and design of connections, such as beam-to-column connections, pose various complexities such as nonlinear behavior of material and geometric condition, irregularities in geometry and boundary condition. The main purpose of these types of connections is to provide adequate structural strength and a sufficiently stiff structure at working loads, and to possess sufficient ductility and strength at overloads such as may occur during a major earthquake. At present the design profession does not have established guidelines for estimating the ultimate moment and shear capacity of these connections. The assumption of linear elastic material behavior of the connections is no longer valid when the elements are stressed beyond the yield stress of the material. For such problems encountered in the design of typical structures, either the closed-form analytical solutions are extremely complex or cannot be obtained at all. Thus, numerical techniques such as finite difference, finite element and boundary integral methods are used. In this study, a finite element program is developed for plastic analysis of connections such as beam-to-column connection using a constitutive law of the material, a three parameter stress-strain relationship, which gives stress explicitly in terms of strain. One hundred and fifteen cases of beam-to-column connections subjected to moment are analysed with the finite element program developed in this study, and the results are compared with the existing approximate solution by yield line theory to propose a simple formula to correlate actual ultimate capacity to the approximate solution.
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Brooke, Nicholas J. "Improving the performance of reinforced concrete beam-column joints designed for seismic resistance." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/8697.
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The testing of thirteen large scale beam-column joints forms the framework for the content of this thesis. The thirteen tests were divided into three series, each of which investigated an aspect of earthquake resistant design of moment resisting frames. The results obtained from testing the first series of four beam-column joints contradicted the conclusion of earlier research that design criterion specifying the ratio of column depth to bar diameter required to anchor beam longitudinal reinforcement at interior beam-column joints was non-conservative when applied to Grade 500E reinforcement. As a result, a database of approximately 100 beam-column joints was assembled and used to parametrically develop an improved design criterion that was shown to satisfactorily predict experimental performance based on the anchorage length provided. It was also shown in the first part of the thesis that the flexural overstrength factor should be the same irrespective of whether Grade 300E or Grade 500E longitudinal reinforcement is used in a beam. This finding contradicts current New Zealand practice, which specifies a higher flexural overstrength factor for Grade 500E reinforcement. The second set of four tests assessed the performance of beam-column joints constructed using inorganic polymer concrete. The properties of inorganic polymer concrete are similar to those of concrete produced using Portland cement, but the production of inorganic polymer concrete releases 80% less "greenhouse gases" into the atmosphere than the production of Portland cement concrete. The results of these tests showed that satisfactory performance can be expected from beam-column joints designed using existing New Zealand standards but constructed using inorganic polymer concrete. The final series of five tests were conducted to assess the performance of beam-column joints when the joint core was constructed using high performance fibre reinforced cementitious composites (HPFRCC) and contained no conventional transverse reinforcement. The results of this testing showed that satisfactory performance could be achieved when the magnitude of the joint core shear stress was commensurate with the strength of the HPFRCC used. It was also evident that HPFRCC is significantly superior to plain concrete with regards to the anchorage of reinforcement within the joint core. A number of comments were made regarding the practicalities of using HPFRCC joint cores in real structures, from which it was concluded that for most structures HPFRCC joint cores are unlikely to be a practical alternative to conventionally reinforced joint cores.
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Lau, Shuk-lei. "Rehabilitation of reinforced concrete beam-column joints using glass fibre reinforced polymer sheets." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B32001630.
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Lau, Shuk-lei, and 劉淑妮. "Rehabilitation of reinforced concrete beam-column joints using glass fibre reinforced polymer sheets." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B32001630.
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Reys, De Otiz Iclea. "Strut-and-tie modelling of reinforced concrete : short beams and beam-column joints." Thesis, University of Westminster, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334612.
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Bowers, Jeremy Thomas. "Nonlinear Cyclic Truss Model for Beam-Column Joints of Non-ductile RC Frames." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50437.
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Reinforced concrete (RC) moment frames comprise a significant portion of the built environment in areas with seismic hazards. The beam-to-column joints of these frames are key components that have a significant impact on the structure's behavior. Modern detailing provides sufficient strength within these joints to transfer the forces between the beams and the columns during a seismic event, but existing structures built with poor detailing are still quite prevalent. Identifying the need and extent of retrofits to ensure public safety through nondestructive means is of primary importance. Existing models used to analyze the performance of RC beam-to-column joints have either been developed for modern, well-detailed joints or are simplified so that they do not capture a broad range of phenomena.
The present study is aimed to extend a modeling technique based on the nonlinear truss analogy to the analysis of RC beam-to-column joints under cyclic loads. Steel and concrete elements were arranged into a lattice truss structure with zero-length bond-slip springs connecting them. A new steel model was implemented to more accurately capture the constitutive behavior of reinforcing bars. The joint modeling approach captured well the shear response of the joint. It also provided a good indication of the distribution of forces within the joint.
The model was validated against three recently tested beam-column subassemblies. These tests represented the detailing practice of poorly-detailed RC moment frames. The analytical results were in good agreement with the experimental data in terms of initial stiffness, strength and damage pattern through the joint.Master of Science
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Xing, Chenxi. "An Analytical Study on the Behavior of Reinforced Concrete Interior Beam-Column Joints." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/92873.
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Reinforced concrete (RC) moment frame structures make up a notable proportion of buildings in earthquake-prone regions in the United States and throughout the world. The beam-column (BC) joints are the most crucial regions in a RC moment frame structure as any deterioration of strength and/or stiffness in these areas can lead to global collapse of the structure. Thus, accurate simulations of the joint behavior are important for assessment of the local and global performance of both one-way and two-way interior BC joints. Such simulations can be used to study the flexural-shear-bond interaction, the failure modes, and sensitivity of various parameters of structural elements. Most of the existing analytical approaches for interior BC joints have either failed to account for the cyclic bond-slip behavior and the triaxial compressive state of confined concrete in the joint correctly or require so many calibrations on parameters as to render them impractical. The core motivation for this study is the need to develop robust models to test current design recommendations for 3D beam-column-slab subassemblies subjected to large drifts. The present study aims to first evaluate the flexural-shear-bond interactive behavior of two-way beam-column-slab interior connections by both finite element and nonlinear truss methodologies. The local performance such as bond-slip and strain history of reinforcing steel are compared with the experimental results for the first time. The reliability of applied finite element approach is evaluated against a series of one-way interior BC joints and a two-way interior beam-column-slab joint. The accuracy and efficiency of the nonlinear truss methodology is also evaluated by the same series of joints. Results show good agreement for finite element method against both global and local response, including hysteretic curve, local bond-slip development and beam longitudinal bar stress/strain distributions. The nonlinear truss model is also capable in obtaining satisfactory global response, especially in capturing large shear cracks. A parametric study is exhibited for a prototype two-way interior beam-column-slab joint described in an example to ACI 352R-02, to quantify several non-consensus topics in
the design of interior BC connections, such as the joint shear force subjected to bidirectional cyclic loading, the development of bond-slip behavior, and the failure modes of two-way interior joints with slab. Results from connections with different levels of joint shear force subjected to unidirectional loading show that meeting the requirements from ACI 352 is essential to maintain the force transfer mechanism and the integrity of the joint. The connections achieved satisfactory performance under unidirectional loading, while the bidirectional monotonic loading decreases the joint shear force calculated by ACI 352 by 10%~26% based on current results. Poorer performance is obtained for wider beams and connections fail by shear in the joint rather than bond-slip behavior when subjected to bidirectional cyclic loading. In general, the study indicates that the ACI352-02 design methodology generally results in satisfactory performance when applied to 2D joints (planar) under monotonic and cyclic loads. Less satisfactory performance was found for cases of 3D joints with slabs.Doctor of Philosophy
Reinforced concrete (RC) moment frames are one of the most popular structure types because of their economical construction and adaptable spaces. Moment frames consist of grid-like assemblages of vertical columns and horizontal beams joined by cruciform connections commonly labelled as beam-column joints. Because of the regularity of the grid and the ability to have long column spacing, moment frames are easy to form and cast and result in wide open bays that can be adapted and readapted to many uses. In RC structures, steel bars embedded in the concrete are used to take tensile forces, as concrete is relatively weak when loaded in tension. Forces are transferred between the steel and concrete components by so-called “bond” forces at the perimeter of the bars. The proper modeling of the behavior of bond forces inside the beam-column joints of reinforced concrete moment frames is the primary objective of this dissertation. Reinforced concrete moment frames constitute a notable proportion of the existing buildings in earthquake-prone regions in the United States and throughout the world. The beam-column joints are the most crucial elements in a RC moment frame structure as any deterioration of strength and/or stiffness in these areas can lead to global collapse of the structure. Physical experimentation is the most reliable means of studying the performance of beam-column joints. However, experimental tests are expensive and time-consuming. This is why computational simulation must always be used as a supplemental tool. Accurate simulations of the behavior of beam-column joints is important for assessment of the local and global behavior of beam-column joints. However, most of the existing analytical approaches for interior beam-column joints have either failed to account for the bond-slip behavior and the triaxial compressive state of confined concrete in the joint correctly or require so many calibration parameters as to render them impractical. The present study aims to provide reliable numerical methods for evaluating the behavior of two-way beam-column-slab interior joints. Two methods are developed. The v first method is a complex finite element model in which the beam-column joint is subdivided into many small 3D parts with the geometrical and material characteristics of each part carefully defined. Since the number of parts may be in the hundreds of thousands and the geometry and material behavior highly non-linear, setting up the problem and its solution of this problem requires large effort on the part of the structural engineer and long computation times in supercomputers. Finite element models of this type are generally accurate and are used to calibrate simpler models. The second method developed herein is a nonlinear truss analogy model. In this case the structure is modelled as nonlinear truss elements, or elements carrying only axial forces. When properly calibrated, this method can produce excellent results especially in capturing large shear cracks. To evaluate the accuracy and to quantify the current seismic design procedure for beam-column joints, a prototype two-way interior beam-column-slab joint described in an example to ACI 352R-02, the current design guide used for these elements in the USA, is analytically studied by the finite element methodology. The study indicates that the ACI352-02 design methodology generally results in satisfactory performance when applied to one-way (planar) joints under monotonic and cyclic loads. Less satisfactory performance was found for cases of three-dimensional (3D) joints with slabs.
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Zerkane, Ali S. H. "Cyclic Loading Behavior of CFRP-Wrapped Non-Ductile Reinforced Concrete Beam-Column Joints." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3000.
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Use of fiber reinforced polymer (FRP) material has been a good solution for many problems in many fields. FRP is available in different types (carbon and glass) and shapes (sheets, rods, and laminates). Civil engineers have used this material to overcome the weakness of concrete members that may have been caused by substandard design or due to changes in the load distribution or to correct the weakness of concrete structures over time specially those subjected to hostile weather conditions. The attachment of FRP material to concrete surfaces to promote the function of the concrete members within the frame system is called Externally Bonded Fiber Reinforced Polymer Systems. Another common way to use the FRP is called Near Surface Mounted (NSM) whereby the material is inserted into the concrete members through grooves within the concrete cover. Concrete beam-column joints designed and constructed before 1970s were characterized by weak column-strong beam. Lack of transverse reinforcement within the joint reign, hence lack of ductility in the joints, and weak concrete could be one of the main reasons that many concrete buildings failed during earthquakes around the world. A technique was used in the present work to compensate for the lack of transverse reinforcement in the beam-column joint by using the carbon fiber reinforced polymer (CFRP) sheets as an Externally Bonded Fiber Reinforced Polymer System in order to retrofit the joint region, and to transfer the failure to the concrete beams. Six specimens in one third scale were designed, constructed, and tested. The proposed retrofitting technique proved to be very effective in improving the behavior of non-ductile beam-column joints, and to change the final mode of failure. The comparison between beam-column joints before and after retrofitting is presented in this study as exhibited by load versus deflection, load versus CFRP strain, energy dissipation, and ductility.
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Ocel, Justin M. "Cyclic behavior of steel beam-column connections with shape memory alloy connecting elements." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19110.
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Bousri, Yahia. "Experimental and analytical study of reinforced concrete external beam-column subjected to cyclic loading." Thesis, University of Bristol, 1994. http://hdl.handle.net/1983/692583ab-1cce-4e31-9250-b1c322c8caef.
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LEI, IAR-FAI, and 李日暉. "Shear Properties of Beam-Column Joints Using High Strength Concretes." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/40501011944408117484.
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碩士國立中央大學
土木工程學系
86
The differences of provisions of the current ACI 318-95joint. Code and the NZS 3101-1995 Code, namely in the amount oftransverse reinforcement within the joints, will affect theseismic performance of the structures deeply. Because of thesetwo Codes are based on normal-strength concrete. Therefore, Theobjective ofthis study is focused on the ACI 318-95 Code andthe NZS 3101-1995 Code when apply high-strength concrete tobeam-column joints. Four beam-column joints specimens accordingto the Codes were tested. Three of them are the high- strengthconcrete specimens and the other one is normal- strengthspecimen. Test results indicated that the high-strength concretespecimens designed according to the ACICode would overly conservative and created congestion of transverse reinforcementin the joint , difficult to construct. Once the specimensconforming to theNZS Code could improve the seismic performanceof the structures and would notresult in congestion of steelwithin the joint.
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李俊賢. "Shear behavior of exterior beam-column joints with self-consolidating concrete." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/24936412831602596524.
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碩士國立中興大學
土木工程學系
92
The purpose of this study is to investigate the shear behavior of exterior beam-column joints with self-consolidating concrete （SCC）and normal concrete. The experimental program consisted of 9 self-consolidating concrete exterior beam-column joints, and 9 normal concrete （NC）exterior beam-column joints. All columns were 4500 mm in length with the cross section of 500 × 300 mm, and the beams were 1000 mm in length with the cross section of 500 × 300 mm. The test parameters included the amount of tie, concrete strength, level of axial force on column, and tie spacing. The following conclusions can be made from the results： 1. Shear strengths of SCC beam-column joints are higher than those predicted by ACI code .The ultimate strengths predicted by ACI code for SCC joints are conservative. 2. The average ratio of joint shear strength of SCC joints to those of NC joints is 1.019. SCC joints have higher shear strength than NC joints. 3. SCC joints have higher shear ductility , the average ratio of shear ductility of SCC joints to those of NC joints is 1.183. 4. The crack shear strengths of SCC joints are higher than those of NC joints by approximately 8.5%. 5. The contribution of transverse reinforcement to ultimate shear strengths of joints is less than 5%. 6. SCC beam-column joints have better crack control over NC beam-column joints. The crack widths of SCC beam-column joints are approximately 60.3﹪of those of NC beam-column joints.
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Liaw, Dyi-Fa, and 廖迪發. "Shear Strength of Reinforced Concrete Beam-Column Joints for Seismic Resistance." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/54890507713367779895.
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碩士國立臺灣科技大學
營建工程系
87
The role of joint hoop reinforcement is investigated by the testing of five specimens of corner beam-column joints. One is designed according to the seismic provisions of ACI 318-95 Code and others are detailed with reduced transverse reinforcement together with greater spacing. The shear strength predictions by the softened strut-and-tie model show sufficient agreement with test results. This study indicates that the greater reduction of joint hoop reinforcement from the ACI 318-95 Code is feasible and that there is no significant changes on shear strength, ductility and the serviceability requirements of crack width and initial stiffness. However, the greater joint hoop reinforcement can improve energy dissipation behavior. Additionally, test results also exhibit that joint hoop yielding cause rapid deterioration of concrete within joint core, and the shear strength of the beam-column joint is therefore decreased.
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Tsai, Chia-Sheng, and 蔡家盛. "Seismic Design of Shear Strength of Reinforced Concrete Interior Beam-Column Joints." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/00683604440749977860.
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碩士國立臺灣科技大學
營建工程系
92
American ACI 318-02 Code requires that the RC beam-column joints be detailed with the similar amount of hooks in the end regions of columns for seismic resistance. This empirically determined amount of hooks creates a congested joint which is very difficult to construct with, especially for the high strength concrete joints. Moreover, the ACI 318-02 Code formula is not applicable in assessing the shear strength of the seismically insufficient joints. The objective of this study is to declare the roles of joint hooks and to define a least amount of joint hooks. According to the softened strut-and-tie model, the recommended amount of hooks is sufficient for the full development of shear strength, and the recommended detailing of hooks is flexible enough for construction. Six interior reinforced concrete beam-column joints were tested under reverse cyclic loading. Test results indicated that the major function of the joint hoop is to carry shear as a tension tie and to constrain the width of crack. This study found that the joint hoop play no role in confining concrete core as required by the ACI 318-02 Code. Less amount of hoop reinforcement with a wider spacing could be used without significantly affecting the performance of joints. The softened strut-and-tie model is capable in estimating the shear strength of joints for both the seismic design and the seismic retrofitting.
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Chang, You-Ren, and 張又仁. "Seismic Testing of Shear Strength of New RC Interior Beam-Column Joints." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/89515840892757414284.
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碩士國立雲林科技大學
營建工程系碩士班
102
Using high-strength reinforcement and concrete have many advantages, including smaller member sizes, lighter structure elements, lesser reinforcement, longer span capability, and more space available for end users. This project investigate how to extending current design methods for frame joints with high-strength reinforced concrete. This project constructed a test database with over 350 reinforced concrete beam-column connections through extensive investigations. Four interior beam-column joint specimens were constructed and tested by cyclic loading to evaluating the design requirements. The test parameters are constant ratios of column-to-beam moment strengths, varying target joint shear stressrange from 15-20 , and transverse reinforcement. Test results showed obvious degradation of joint shear strengths as the increase of story drift and ductility. The minimum column dimension of 24 times diameter of beam bars isrelatively adequate for high-strength reinforcement. Test results shows that the transverse perpendicular to those two opposite faces where beams frame into the joint can be liberated without affecting the seismic performance up to 6% drift.
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Chang, Chia-Jung, and 張家榮. "Seismic Testing of Shear Strength of New RC Exterior Beam-Column Joints." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/63474848722509062606.
Full textAbstract:
碩士國立雲林科技大學
營建工程系碩士班
102
New RC structures have many advantages, including smaller member sizes, lighter structure elements, lesser reinforcement, longer span capability, and more space available for end users. This study investigate how to extending current design methods for New RC frame joints. A test database was constructed with over 350 reinforced concrete beam-column connections through extensive investigations. Based on the database investigation, this study designed five T-shaped beam-column joint specimens made with high-strength reinforcement and concrete to evaluate current ACI design requirement. Among the tested specimens, the column-to-beam moment strengths ratios are below 2 and the target joint shear stresses ranged between 10 psi and 17 psi. The amount of joint transverse reinforcement are design by taken the maximum yield strength of 700 MPa. The beam longitudinal bars are terminated by headed bars with code-compliant embedded length into the joint and confined with adequate transverse reinforcement. Specimens are designed to extend current ACI design recommendations for New RC structures. Test results showed that the joint shear stress of 15 psi and higher will result in J failure. Adding more than enough transverse reinforcement could not change the failure significantly. Following correct ACI code, the limitation of joint shear stress of 12 psi for T-shaped joint could not make the joint resistance up to 6% drift ratio, unless providing more transverse reinforcement. The inclination of diagonal struts are affected by the anchorage of headed bars and we recommended to use in place of to estimate the joint effective depth. Thereby, the target joint shear stress of 12 psi could keep the joint resistance beyond the drift ratio of 6%. Also, the provided embedded length of headed bars in the tested joints are about 1.04 times the development length required per ACI 318 code, but the clear spacing between bars are reduced to 2 . Test results showed these closely-spaced headed bars could fully developed their yield strength in a well-confined joint core. In 4% drift cycles, more than 50% of transverse reinforcement in the direction of shear reached its yield strength and the average stress were greater than 700 MPa. Therefore, we recommended that the design yield strength of joint transverse reinforcement could not be taken greater than 700 MPa for New RC frame joints.
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Hasaballa, Mohamed. "GFRP-reinforced concrete exterior beam-column joints subjected to seismic loading." 2014. http://hdl.handle.net/1993/24454.
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Glass fibre-reinforced polymer (GFRP) reinforcement is used in reinforced concrete (RC) infrastructure to avoid steel corrosion problems. The behaviour of GFRP reinforcement under seismic loading in RC frame structures has not been widely investigated. The behaviour of beam-column joints significantly influences the response of the Seismic Force Resisting Systems. Therefore, both the design and detailing of the beam-column joints are critical to secure a satisfactory seismic performance of these structures. However, the current Canadian FRP design codes (CSA 2012, CSA 2006) have no considerable seismic provisions, if any, due to lack of data and research in this area. Such lack of information does not allow for adequate designs and subsequently limits the implementation of FRP reinforcement as a non-corrodible and sustainable reinforcement in new construction. Therefore, it deemed necessary to track areas of ambiguity and lack of knowledge to provide design provisions and detailing guidelines.
This study investigated the seismic behaviour of the GFRP-RC exterior beam-column joints. The study consisted of an experimental phase, in which ten full-scale T-shaped GFRP-RC specimens were constructed and tested to failure, and an analytical phase using finite element modelling (FEM). Specimens in the experimental phase were designed to investigate the anchorage detailing of beam longitudinal reinforcement inside the joint (using either bent bars or headed bars) and to evaluate the shear capacity of the joint.
In the analytical phase, a commercial FEM software (ATENA-3D) was used to run a parametric study that investigated the influence of the presence of lateral beams, axial load on the column, applied shear stresses in the joint, and the concrete strength.
Test results showed that the performance of the specimens reinforced with GFRP headed bars was comparable to their counterparts reinforced with bent bars up to 4.0% drift ratio. The difference in the reinforcement surface conditions had insignificant influence on the overall behaviour. Moreover, it was concluded that the shear capacity of GFRP-RC beam-column joints is 0.85 √f'c. Furthermore, an evaluation of the relevant seismic provisions in the CSA/S806-12 (CSA 2012) was carried out and some recommendations were proposed for consideration in the future updates of the CSA/S806-12.
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Khalili, Ghomi Shervin. "Seismic performance of GFRP-RC exterior beam-column joints with lateral beams." 2014. http://hdl.handle.net/1993/23304.
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In the past few years, some experimental investigations have been conducted to verify seismic behaviour of fiber reinforced polymer reinforced concrete (FRP-RC) beam-column joints. Those researches were mainly focused on exterior beam-column joints without lateral beams. However, lateral beams, commonly exist in buildings, can significantly improve seismic performance of the joints. Moreover, the way the longitudinal beam bars are anchored in the joint, either using headed-end or bent bars, was not adequately addressed. This study aims to fill these gaps and investigate the shear capacity of FRP-RC exterior beam-column joints confined with lateral beams, and the effect of beam reinforcement anchorage on their seismic behaviour. Six full-scale exterior beam-column joints were constructed and tested to failure under reversal cyclic loading. Test results showed that the presence of lateral beams significantly increased the shear capacity of the joints. Moreover, replacing bent bars with headed-end bars resulted in more ductile behaviour of the joints.
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Lee, Hung-Jen, and 李宏仁. "A Study of Shear Strength of Reinforced Concrete Beam-Column Joints for Earthquake Resistance." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/42733424064159354423.
Full textAbstract:
博士國立臺灣科技大學
營建工程系
88
A rational model for determining the shear strengths of the reinforced concrete beam-column joints for earthquake resistance is proposed. This analytical model, termed as the softened strut-and-tie model, includes the influential parameters of shear strengths of beam-column joints. On the basis of analytical and experimental studies, a simplified procedure for the design of the shear strengths of the beam-column joints is also recommended. Beam-column joints of moment-resisting frames are geometrical discontinuity regions subjected to very high horizontal and vertical shears under earthquake-introduced loading. The joints are assumed to resist diagonal compression force and to fail in crushing of concrete. The proposed model simulates the shear-resisting mechanisms of joints with the strut-and-tie concept, which satisfies equilibrium, compatibility, and constitutive laws of cracked reinforced concrete. In the proposed model, web reinforcement plays two roles. One is to form tension ties and to provide shear-transferring paths. The other is to control the crack widths and to retard the softening process of the cracked concrete. The strength condition of the diagonal compression failure is defined as the crushing of concrete strut in the model. The proposed model could analyze the shear strengths not only for beam-column joints, but also for similar discontinuity regions failing in diagonal compressions, such as deep beams, corbels, and squat walls. Test Results of 10 high strength concrete exterior beam-column joints indicated that the shear capacity of joint is the most significant parameter for the seismic performance. If the shear capacity of joint is adequate, the great reduction of joint hoop reinforcement from the ACI Code requirement is possible with little or no influence on the seismic behavior of the specimens. However, test results also indicated that elastic hoop reinforcement maintains the integrity and retards the decay of joint strength during large cyclic reversals of displacements. The joint reinforcement is found to be effective as horizontal or vertical ties if sufficient anchorage or development length of the reinforcement is provided. A proposed simplified method predicts the shear strengths of discontinuity regions with the same accuracy of the detailed approach. The proposed simple method is inversed to be a design procedure. Beam-column joints designed with proposed procedure have the same level of shear strengths but less amount of hoop reinforcement in comparison with ACI 318-95 Code. The proposal provides more degrees of freedom for engineers to change design parameters and to avoid the possible congestion of reinforcement in a beam-column joint. Integrated and simplified design procedure, which incorporates the actual shear resisting mechanisms as postulated by the softened strut-and-tie model, has been formulated to improve the current shear design regulations for discontinuity regions in reinforced concrete members.
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Erwin, Lim, and 林孝勇. "Shear Strength Prediction of Eccentric Beam-Column Joints Using Softened Strut-and-Tie Model." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/72181814593653872612.
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碩士國立臺灣大學
土木工程學研究所
97
Several studies showed that the eccentricity between beam and column connections has a detrimental effect on the joint shear strength. With regard to this issue, current ACI 318-08 code restricts the average shear stress on a horizontal plane within the joint, which equals to the effective joint width times column depth. The formula of effective joint width given in ACI 318-08 may be too conservative for eccentric beam-column joints. This thesis suggests a more rational formula of effective joint width associated with the softened strut-and-tie (SST) model for eccentric beam-column joints. Using the proposed effective joint width, the shear strength predictions of SST model agreed well with the results of 18 eccentric joint specimens failed in shear. Several available definitions of effective joint width are also used together with proposed effective joint width to estimate joint shear strength using the average joint shear stress limits given in ACI 318-08 design equation. This combination was successfully verified with available 126 beam-column joints with or without eccentricity in literature. Analysis shows that proposed effective joint width can well predict joint shear strength of eccentrically connected beam-column joints and preserves the accuracy of current adopted effective joint width in ACI 318-08. Furthermore, some sensitivity analysis are performed to justify several assumptions.
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Liu, Yi-Feng, and 呂宜峰. "A Study of Shear Strength Degradation of High Strength Concrete Beam-Column Joints for Seismic Resistance." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/62415970639707735883.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
89
For maintaining the dissipation capacity of structural frames, the failures of beam-column joints should be avoided. Therefore, an evaluation measure to determine the adequacy of strength to prevent the joint failure is needed. The ACI 318-99 Code could not clearly evaluate the shear strength of various joints. The current code adopts the empirical limitations on parameters to ensure the joint on achieving it’s shear strength. Moreover, the code-provided equation does not reflect the shear strength degradation under the increasing ductility. Therefore, the current code provision of the joint strength is not suitable for above purpose. The objective of this study was to estimate the shear strength degradation of beam-column joint under the increasing ductility. Total of 6 specimens without hoop confinement in the joint were tested. The test parameters include the beam steel ratio, which generates different stress levels and ductility requirements of joint, and the axial loading of column, which simulates the loading of low-rise buildings. Based on the softened strut-and-tie model and the test results, a model to predict the shear strength degradation of beam-column joints for seismic resistance is proposed.