Fig 2- - uploaded by Shamim A. Sheikh
Content may be subject to copyright.
Source publication
Many reinforced concrete structures that were built approximately 40 years ago or earlier, and some built much more recently, were done so without adequate consideration for shear-critical behavior under seismic conditions. Such buildings are of great concern because, in the event of an earthquake, they may fail in a brittle and catastrophic manner...
Context in source publication
Context 1
... number of deficiencies were uncovered including: 1) the shear reinforcement amounts provided in some of the beams were inadequate to develop the beams' full flexural capacities; 2) the beams' longitudinal reinforcement did not fully penetrate the column joints as required by seismic detailing provisions, but rather was terminated short (refer to Fig. 2); and 3) in the lower story columns, the lateral confining reinforcement was inadequate with respect to its amount and spacing. Similar details have been used for a number of such structures recently constructed throughout the Americas. These and other deficiencies rendered the structure's expected performance under design seismic ...
Similar publications
Numerous reinforced concrete frames have collapsed in major earthquakes because of severe local damage at the ends of columns. Many of these frames were designed and built according to out-of-date codes in which earthquake loads were either not taken into account or not sufficiently considered. To date, there are still a large number of such nonduc...
To analyze the influence of CFRP (Carbon Fiber Reinforced Polymer) reinforcement ratio and CFRP sheet on the self-centering performances of concrete circular columns, five concrete circular columns were tested under the low-cyclic reversed load in this work. The five concrete circular columns included 1 RC (Reinforced Concrete) column, 2 CFRP bars...
Existing reinforced concrete (RC) building structures constructed until the mid-1970's, prior to the enforcement of modern seismic design philosophies, are expected to behave poorly when subjected to earthquake actions. The response and damage evolution of RC structures when subjected to severe cyclic loading, such as the ones induced by earthquake...
![Fig. 2. Stress-Strain relationships for different materials [40,41].](profile/Baraa-R-Alnemrawi/publication/363894381/figure/fig1/AS:11431281094257851@1667436644313/Stress-Strain-relationships-for-different-materials-40-41_Q320.jpg)
![Fig. 3. NLFEA geometry and reinforcement arrangements [26].](profile/Baraa-R-Alnemrawi/publication/363894381/figure/fig2/AS:11431281094268805@1667436644347/NLFEA-geometry-and-reinforcement-arrangements-26_Q320.jpg)
![Fig. 7. NLFEA punching shear cracks [26].](profile/Baraa-R-Alnemrawi/publication/363894381/figure/fig4/AS:11431281094296225@1667436644503/NLFEA-punching-shear-cracks-26_Q320.jpg)
This study investigates the punching shear behavior of reinforced concrete (RC) flat slabs using theoretical and non-linear finite element analysis techniques (NLFEA). The internal slab-column connection was studied under the combined effect of openings and loading eccentricity. No additional reinforcement was introduced after the opening was made...
A major cause underlying the collapse of reinforced concrete (RC) moment-resisting frames observed in past earthquakes is the shear failure of nonseismically detailed exterior beam–column joints. A number of studies have investigated the external application of fiber-reinforced polymer (FRP) composites for the seismic rehabilitation of these member...
Citations
... To achieve this objective, a) inclusive experimental investigations, and b) reliable nonlinear macromodels for the three main structural elements; 1) frames, 2) MIWs, and 3) SWs; of the multistory RC buildings are involuntary. Regarding a) the experimental investigations, there are many studies for the structural behavior of the RC frames with or without MIWs (Vecchio and Emara 1992;Angel et al. 1994;Mehrabi et al. 1996;Negro et al. 1996;Carvalho et al. 1999;Duong et al. 2007;Sharma et al. 2013;Basha and Kaushik 2016;Shan et al. 2016;Pallarés et al. 2021;Demirel et al. 2023), and the RC SWs (Chen and Qian 2002;Thomsen and Wallace 2004;Dazio et al. 2009;Alarcon et al. 2014;Kolozvari et al. 2015;Takahashi et al. 2013;Park et al. 2015;Sanada et al. 2018;Wang and Wang 2021) under lateral loading. The references introduced in this paper were only indicative and not exhaustive. ...
... If the shear deformation is prevailing, the shear PH becomes mandatory. The shear failure of RC frames was experimentally investigated (Vecchio and Emara 1992;Simokaichi 1994;Elwood and Moehle 2003;Duong et al. 2007), and different shear models were introduced (Watanabe and Lee 1998;Elwood 2004;Elwood and Moehle 2005). For modeling the shear failure of RC joints, many macromodels such as Pan et al. (2017), Sharma et al. (2011a), Yu (2006), Ziyaeifara and Noguchib (2000), and Ghobarah and Biddah (1999) were presented. ...
... For the ten simulated frames, Table 3 presents the layout, loads, concrete properties, steel properties and reinforcement details (Mehrabi et al. 1996, Duong et al. 2007, and Sharma et al. 2013). All the ten frames were subjected to pushover analysis except the F-B-2S model that was subjected to two loading phases (loading and unloading). ...
The structural behavior prediction of the multistory reinforced concrete (RC) buildings with masonry infill walls (MIWs) during earthquakes is challenging. This paper presents a nonlinear macromodeling strategy seeking a simple, reliable, and low-cost computational analysis of the multistory RC buildings that comprise MIWs, and that use frames or shear walls (SWs) for resisting the lateral load. The strategy employed four plastic hinge (PH) models for tracking the deformations (flexural, shear, and torsion) of the frame elements and joints, a multilinear plastic link for modeling the MIW, and a nonlinear multilayer shell element for modeling the SW. A flexural PH model characterized by discretization into fibers, a recommended position, and an iterative estimating for the PH length using a distinct formula for each loading level was proposed. This strategy was validated through eleven macromodels investigating four bare frames, four MIWs frames, and a SW where the average ultimate lateral load error was 9.2%, 3.6%, and 0.4%, respectively. Finally, the structural behavior of real ten-story buildings with/without MIWs was investigated. The results showed that the MIWs increased the shear capacity and the lateral stiffness with an average of 44.3% and 118.6%, respectively. Also, both the frames buildings with MIWs and the bare SWs buildings showed approximately equal lateral load capacities. Local damages in the RC vertical elements and yielding of the MIWs were recorded simultaneously. However, the MIWs yielding (and also failure) occurred earlier for the frames buildings compared with the SWs buildings in which the stress was relaxed in their MIWs.
... In addition to the application of FRP in strengthening structural members and joints, the performance of FRP-strengthened frames has been investigated by many scholars. Duong et al. [15] studied the seismic performance of the low ductility frame reinforced with CFRP and found that the CFRP can effectively improve the bearing capacity, ductility and energy dissipation capacity of the frame. El-Sokkary and Galal [16] used finite element analysis to study the reinforcement effectiveness of the existing non-ductile RC frame structures using different reinforcement methods, and the analysis showed that the seismic resistance of the whole structure can be effectively improved by wrapping the beams and columns with FRP. ...
To study the seismic strengthening of damaged reinforced concrete (RC) frames using CFRP sheets, this study designed and tested the scaled 2-bay and 2-storey RC frame specimens. After applying a low cyclic horizontal load to simulate the initial damage to the specimen in an earthquake disaster, CFRP was used to strengthen the joints of the damaged RC frame. Pseudo-static tests of strengthened specimens and counterpart specimens were then carried out. Seismic performance, including stiffness, load capacity, ductility and energy dissipation were further analyzed. The failure mode of strengthened RC frame structures showed excellent ductility. The results demonstrated that the strengthening method involving wrapping CFRP can significantly improve the maximum horizontal bearing capacity, initial stiffness and energy dissipation capacity of the non-ductile reinforced concrete frame structure. The average displacement ductility coefficient of strengthened specimen can be enhanced to 3.41 compared with that of counterpart specimen (3.00). The pushover analysis based on the OpenSees model determined that the prototype frame with CFRP strengthening can maintain structural integrity and safety, with its maximum interstorey displacement angle below the limit of seismic specification (i.e., 1/50 in a severe earthquake). This study can contribute to the development of practical and efficient methods for restoring and improving the performance of damaged RC frames in seismic-prone regions.
... The response of reinforced concrete beam can be admitted as linear under normal conditions [2], the result can turn out to be non-linear when reinforced concrete beams are given a very extreme load such as seismic event [3]. Non-linear response can also occur when the applied load is greater than the capacity of the reinforced concrete beam such as, poor design or construction [4][5][6][7] so that the influence of concrete and steel reinforcement greatly affects the non-linear response of these elements. For concrete, the non-linear response causes complex concrete cracking behaviour, where in general the concrete will exhibit crack formation and opening/closing of pre-existing cracks, crack slip and shear transfer along the crack interface and crack-to-crack interactions [8][9][10][11]. ...
... The proposed formulation is validated against 170 reinforced concrete specimens found in literature including 161 simply supported beams, 6 shear walls, and 3 planar frames. The specimens are selected from experimental studies of Bresler and Scoredelis (1963) [38], Krefeld and Thurston (1966) [39], Lefas et al. (1990) [40], Vecchio and Balopoulou (1990) [41], Vecchio and Emara (1992) [42], Angekolas et al. (2001) [43], Vecchio and Shim (2004) [44], Duong et al. (2007) [45], and Sherwood et al. (2007) [46]. In the selected specimens, shear spandepth ratio varies from 2 to 9.8, percentage of longitudinal reinforcement ratio varies from 0.5% to 3.96%, percentage of transverse reinforcement ratio varies from 0% to 0.8%, depth varies from 0.3 m to 1.51 m, and concrete strength varies from 12.2 MPa to 48.5 MPa. ...
... The proposed formulation is validated against 170 reinforced concrete specimens found in literature including 161 simply supported beams, 6 shear walls, and 3 planar frames. The specimens are selected from experimental studies of Bresler and Scoredelis (1963) [38], Krefeld and Thurston (1966) [39], Lefas et al. (1990) [40], Vecchio and Balopoulou (1990) [41], Vecchio and Emara (1992) [42], Angekolas et al. (2001) [43], Vecchio and Shim (2004) [44], Duong et al. (2007) [45], and Sherwood et al. (2007) [46]. In the selected specimens, shear spandepth ratio varies from 2 to 9.8, percentage of longitudinal reinforcement ratio varies from 0.5% to 3.96%, percentage of transverse reinforcement ratio varies from 0% to 0.8%, depth varies from 0.3 m to 1.51 m, and concrete strength varies from 12.2 MPa to 48.5 MPa. ...
... The first RC frame used for the validation is a two-storey single bay frame, experimented by Duong et al. (2007) [45]. Fig. 13 shows the loading arrangement, geometry and cross-sectional details of the frame. ...
This paper focuses on a novel finite element formulation which can predict the bending moment-shear force-axial force interaction of reinforced concrete frames and walls, and validate it against 170 experiments available in literature. This distributed plasticity element is established on force-based finite element method, where the relationship between element nodal forces and section forces are exactly known. Hence, element discretization is nonessential when modelling frames using this formulation, reducing the number of degrees of freedom in the numerical model compared to displacement-based formulations. The computations are carried out at four hierarchical levels, namely structure, element, section and fibre. There are two nested iterative procedures at the structure level and the section level. In the existing formulation, these iterative procedures are computationally demanding due to use of initial stiffness matrices. Furthermore, it uses Modified Compression Field Theory at the fibre level, which has inherent drawbacks compared to its more evolved version, the Disturbed stress Field Model. The current study refines the iterative procedures at structure and section levels to fully operate with tangent stiffness matrices to improve the speed of convergence. In addition, the Modified Compression Field Theory is replaced with the Disturbed stress Field Model at the fibre level to compute fibre resisting force for a given fibre deformation, accounting for both averaged behaviour and local crack slip. The novel element is validated by comparing the predicted results with experimental results of 170 tests found in the literature. It is shown that the novel element predicts the load carrying capacity well with an average experimental-to-predicted load carrying capacity ratio of 0.99 and a coefficient of variation of 12.8%. Furthermore, the element can be used to discuss the different failure mechanisms of reinforced concrete frame elements.
... The application of the proposed model at the system level was investigated on a two-story, single-span RC frame with shear-critical beams tested by Duong et al. 32 The geometry of the frame, as well as cross-section dimensions and reinforcement details, are shown in Fig. 11. The base shear versus lateral roof displacement responses reported from the experimental test and calculated by the analysis procedures mentioned in the previous section are shown in Fig. 12. ...
The lumped plasticity method is an efficient analytical approach
to assess the system-level performance of reinforced concrete
(RC) structures. Through this analysis approach, the nonlinearity
effects are calculated using plastic hinges located in critical parts
of the structure. Because of the complexity associated with shear-related mechanisms in RC members, the number of shear hinge
models developed in the literature are limited. This paper presents
a comprehensive shear hinge model for RC beams capable
of capturing advanced mechanisms such as interactions between
shear force and bending moment, effects of nonlinear stress and
strain distributions through the section, and compression softening
effect in concrete. The model provides closed-form equations for
five key points on the shear force-shear deformation response by
satisfying the compatibility, equilibrium, and constitutive relationships.
By comparing the performance of the model against test results, other analysis methods, and design codes at the component and system level, the effectiveness of the model in capturing the shear behavior is demonstrated.
... Such a structure was tested at the University of Toronto to examine the behavior of shear-critical RC frames under seismic loading. 36 The test specimen was a planar twostory single bay frame with a total height of 4.6 m and a span of 2.3 m. The loading on the frame consisted of two constant vertical forces applied at the top of the columns, as well as a controlled lateral displacement applied at the centerline of the top beam. ...
... F I G U R E 8 Measured and predicted load-displacement response of a two-story frame tested by Duong et al36 T A B L E 1 Comparison of experimental and analytical load levels at important events from the behavior of the frame wide shear crack with significant slip displacements as described in failure mode (ii) in Section 2.5. As prior to this event the model predicts flexural yielding of the end sections of the bottom beam, the formulation captures well the combined flexure-shear failure mode of the frame observed in the test. ...
The nonlinear analysis of large complex reinforced concrete (RC) frame structures with shear-critical members requires numerical approaches that combine high accuracy and computational efficiency. At the same time, existing modeling approaches either involve detailed and costly discretization of the deformations in the frame members (displacement-based approaches), or compromise on accuracy by greatly simplifying (or even neglecting) shear effects. This paper presents a novel nonlinear force-based fiber beam-column element that addresses both these challenges. The element is capable of capturing the complex moment-axial-shear interaction response of planar RC frames and walls, while at the same time requiring minimum discretization. The proposed formulation consists of two nested iterative procedures at the structure and sectional levels. The introduction of the sectional level procedure explicitly satisfies sectional equilibrium, which is not achieved in either existing displacement or force-based line element formulations. As a result, a stable convergence of all average strain, local crack strain, and slip strain components of the constitutive relationship is ensured. The efficiency and accuracy of the proposed element formulation is illustrated with the help of beam and frame tests from the literature.
K E Y W O R D S axial-moment-shear interaction, force-based finite element formulation, nonlinear response, shear-critical reinforced concrete frames
... (Homam et al., 2001;Kharal and Sheikh, 2018;Sheikh and Homam, 2004;Sheikh and Yau, 2002). An industrial structure was also studied which was found to be shear critical and deficient for seismic resistance [ Figure 12(c)] (Duong et al., 2007). Based on an extensive research program in which half scale models of the prototypes were tested in the lab, innovative techniques were developed to rehabilitate the structures in a cost-effective manner with minimal closure time of the structures. ...
Community resilience against major disasters is a multidisciplinary research field that garners an ever-increasing interest worldwide. This paper provides summaries of the discussions held on the subject matter and the research outcomes presented during the Second Resilience Workshop in Nanjing and Shanghai. It, thus, offers a community view of present work and future research directions identified by the workshop participants who hail from Asia - including China, Japan and Korea; Europe and the Americas.
... (Homam et al., 2001;Kharal and Sheikh, 2018;Sheikh and Homam, 2004;Sheikh and Yau, 2002). An industrial structure was also studied which was found to be shear critical and deficient for seismic resistance [ Figure 12(c)] (Duong et al., 2007). Based on an extensive research program in which half scale models of the prototypes were tested in the lab, innovative techniques were developed to rehabilitate the structures in a cost-effective manner with minimal closure time of the structures. ...
... Geometry and loading of the experimental RC column of Germano et al [37] Result of the analytical model and the experimental RC columns of Germano et al [37] . 10. a) Experimental frame of Dong et al [38] b) Result of the analytical model and the experimental frame of Dong et al[38] . 11. a) Experimental frame of Vecchio and Emara[39] b) Result of the analytical model and the experimental frame of Vecchio and Emara[39] ...
Today, most seismic design codes reduce the lateral elastic force by the behavior factor to design structures, so that by designing a structure based on elastic analysis, the effects of non-elastic behavior of the structure are applied. To obtain a behavior factor of structures, a nonlinear analysis is necessary. Research has shown that the nonlinear behavior of RC members depends on factors such as the effect of varying axial load, the effect of shear failure of the members and the effect of the buckling of the longitudinal bars. It is now generally accepted that axial load plays a dominant role in evaluating the seismic behavior of reinforced concrete columns. However columns, especially the exterior ones, can be subjected to varying axial loads depending on the lateral loads. Also the effects of shear on beams and columns are usually neglected in nonlinear analysis, which is carried out based on the flexural behavior of each element. In this research, the behavior factor of 2, 4, and 8 story reinforced concrete frames with intermediate and special ductility based on the proposed nonlinear analysis is considered. Initially, for verification, the proposed nonlinear analysis model was compared with existing experimental models. The verification results show that the proposed model has a very high accuracy. Designing and detailing of the 2, 4 and 8 story reinforced concrete structures are on the basis of the regulation of the Standard 2800 and the National building regulation chapter 9. In order to obtain the behavior of the 2, 4, and 8 story reinforced concrete frames, the effect of varying axial load, shear failure of the members and the buckling of the longitudinal bars are considered in nonlinear analysis. The behavior factor is mostly effected by ductility factor and over strength factor. The ductility factor has dependence with ductility of the reinforced concrete frames. To obtain ductility of reinforced concrete frames, ultimate deformation is needed. To calculate the frames' behavior factor, various criteria are used to calculate the ultimate deformation of frames. One of the criteria is the deformation correspond to the 0.75 percent of ultimate rotation in critical structure member. The other criteria is the deformation correspond to ultimate rotation of critical structure member. The results of the study and comparison of the obtained behavior factor with the proposed behavior factor of the reinforced concrete structures of Standard 2800 with intermediate and special ductility have shown that the calculated behavior factor for 2, 4 and 8 story reinforced concrete frames is bigger than the behavior factor in Standard 2800. Also the results indicate that the calculated behavior factor with the ultimate deformation correspond to the 75 percent of ultimate rotation in critical structure member is close to the proposed value of Standard 2800. In intermediate reinforced concrete frames, the amount of ductility factor and over strength factor decreased when the height of the reinforced concrete frames raised, which is not seen in concrete frames with special ductility.
... B. The frame tested by Duong et al. [31] Duong et al. [31] in 2007, investigate the shear effect on the RC frame capacity. The frame was constructed with a center-to-center span of 1900 mm, a story height of 2100 mm and an overall height of 4600 mm. ...
... B. The frame tested by Duong et al. [31] Duong et al. [31] in 2007, investigate the shear effect on the RC frame capacity. The frame was constructed with a center-to-center span of 1900 mm, a story height of 2100 mm and an overall height of 4600 mm. ...
... V. PARAMETRIC STUDY OF THE EFFECT OF STEEL FIBERS ON THE CAPACITY OF RC FRAMES In this section to consider the effect of the steel fibers on the shear behavior, the frame of Duong et al. [31] is investigated because the failure mode of this frame is shear failure. So the steel fibers with the percentage of 1 and 1.5 is used in the beams and columns of the frame and nonlinear analysis with the proposed model is performed. ...
The result of the past earthquakes have shown that insufficient amount of stirrups and brittle behavior of concrete lead to the shear and flexural failure in reinforced concrete (RC) members. In this paper, an analytical model proposed to predict the nonlinear behavior of RC and SFRC elements and frames. In this model some important parameter such as shear effect, varying axial load, and longitudinal bar buckling are considered. The results of analytical model were verified with experimental tests. The results of verification have shown that the proposed analytical model can predict the nonlinear behavior of RC and SFRC members and also frames accurately. In addition, the results have shown that use of steel fibers increased bearing capacity and ductility of RC frame. Due to this enhancement in shear strength and ductility, insufficient amount of stirrups, which resulted in shear failure, can be offset with usage of the steel fibers. In addition to the steps taken, to analyze the effects of fibers percentages on the bearing capacity and ductility of frames parametric studies have been performed to investigate of this effects.
