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Alex Sousa
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One-Way Slabs In Transition Between One-Way Shear And Punching
Experiments And Recent Insights For Evaluation
Bridge deck slabs are members on which one-way reinforced concrete slabs are found frequently loaded by concentrated loads. Although the one-way shear failure mechanism has gathered more attention in the past years, both one-way shear and two-way shear mechanisms may be critical for such loading conditions. This paper addressed the ultimate capacity of thin one-way reinforced concrete slabs subjected to concentrated loads and yielding of the flexural reinforcement. In practice, the test setup studied was devised to represent short-span rural bridges frequently found in Brazil. The experimental program included 12 tests performed on 6 slabs applying the concentrated loads at varied positions. All tests started to fail by punching shear. Nevertheless, both one-way shear and punching shear cracks were observed at ultimate states after shear redistribution. The reinforcement yielding followed by excessive flexural cracking hampered the arching action activation for loads closer to the support. The comparison of experimental and calculated resistances using standard code-based expressions suggests that improvements in unitary shear capacity could be supported as a result of slabs' transverse load distribution capacity. Alternatively, increasing the effective shear width can help estimate one-way shear capacity for loads near to the support.
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Bridge deck slabs are members on which one-way reinforced concrete slabs are found frequently loaded by concentrated loads. Although the one-way shear failure mechanism has gathered more attention in the past years, both one-way shear and two-way shear mechanisms may be critical for such loading conditions. This paper addressed the ultimate capacity of thin one-way reinforced concrete slabs subjected to concentrated loads and yielding of the flexural reinforcement. In practice, the test setup studied was devised to represent short-span rural bridges frequently found in Brazil. The experimental program included 12 tests performed on 6 slabs applying the concentrated loads at varied positions. All tests started to fail by punching shear. Nevertheless, both one-way shear and punching shear cracks were observed at ultimate states after shear redistribution. The reinforcement yielding followed by excessive flexural cracking hampered the arching action activation for loads closer to the support. The comparison of experimental and calculated resistances using standard code-based expressions suggests that improvements in unitary shear capacity could be supported as a result of slabs' transverse load distribution capacity. Alternatively, increasing the effective shear width can help estimate one-way shear capacity for loads near to the support.
Bridge deck slabs without shear reinforcement under concentrated loads close to line supports may
develop different shear failure modes: (i) one-way shear by shear-compression or flexure-shear failure mechanisms and (ii) two-way shear or punching shear under asymmetrical loading conditions. Notably, most publications concentrate on one of the failure modes and do not delve into the transition between these failure modes. This study proposes to discuss the level of precision of the Critical Shear Crack Theory (CSCT) to predict the shear capacity of slabs subjected to transitional failure modes in shear due to asymmetrical load or support conditions. For this purpose, the CSCT models of one-way shear and two-way shear are coupled with Linear Elastic Finite Element Analyses (LEFEA) to evaluate the nonuniform distribution of shear forces and bending moments around the loaded area and on the control sections used. The use of LEFEA aids in understanding the change of failure modes according to parameters such as the member width to effective depth ratio and the shear span. The results indicate that the CSCT coupled with LEFEA allows for accurate predictions of the shear and punching shear capacity of slabs according to the governing failure mode of the tests.
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develop different shear failure modes: (i) one-way shear by shear-compression or flexure-shear failure mechanisms and (ii) two-way shear or punching shear under asymmetrical loading conditions. Notably, most publications concentrate on one of the failure modes and do not delve into the transition between these failure modes. This study proposes to discuss the level of precision of the Critical Shear Crack Theory (CSCT) to predict the shear capacity of slabs subjected to transitional failure modes in shear due to asymmetrical load or support conditions. For this purpose, the CSCT models of one-way shear and two-way shear are coupled with Linear Elastic Finite Element Analyses (LEFEA) to evaluate the nonuniform distribution of shear forces and bending moments around the loaded area and on the control sections used. The use of LEFEA aids in understanding the change of failure modes according to parameters such as the member width to effective depth ratio and the shear span. The results indicate that the CSCT coupled with LEFEA allows for accurate predictions of the shear and punching shear capacity of slabs according to the governing failure mode of the tests.
...
Bridge deck slabs without shear reinforcement under concentrated loads close to line supports may
develop different shear failure modes: (i) one-way shear by shear-compression or flexure-shear failure mechanisms and (ii) two-way shear or punching shear under asymmetrical loading conditions. Notably, most publications concentrate on one of the failure modes and do not delve into the transition between these failure modes. This study proposes to discuss the level of precision of the Critical Shear Crack Theory (CSCT) to predict the shear capacity of slabs subjected to transitional failure modes in shear due to asymmetrical load or support conditions. For this purpose, the CSCT models of one-way shear and two-way shear are coupled with Linear Elastic Finite Element Analyses (LEFEA) to evaluate the nonuniform distribution of shear forces and bending moments around the loaded area and on the control sections used. The use of LEFEA aids in understanding the change of failure modes according to parameters such as the member width to effective depth ratio and the shear span. The results indicate that the CSCT coupled with LEFEA allows for accurate predictions of the shear and punching shear capacity of slabs according to the governing failure mode of the tests.
develop different shear failure modes: (i) one-way shear by shear-compression or flexure-shear failure mechanisms and (ii) two-way shear or punching shear under asymmetrical loading conditions. Notably, most publications concentrate on one of the failure modes and do not delve into the transition between these failure modes. This study proposes to discuss the level of precision of the Critical Shear Crack Theory (CSCT) to predict the shear capacity of slabs subjected to transitional failure modes in shear due to asymmetrical load or support conditions. For this purpose, the CSCT models of one-way shear and two-way shear are coupled with Linear Elastic Finite Element Analyses (LEFEA) to evaluate the nonuniform distribution of shear forces and bending moments around the loaded area and on the control sections used. The use of LEFEA aids in understanding the change of failure modes according to parameters such as the member width to effective depth ratio and the shear span. The results indicate that the CSCT coupled with LEFEA allows for accurate predictions of the shear and punching shear capacity of slabs according to the governing failure mode of the tests.
Most models of shear strength used to estimate the shear capacity of wide reinforced concrete members without shear reinforcement do not take into account the structural system or the support conditions. However, some experimental results indicate that bending moment can have a positive influence on members with predominant flexural action, contrary to most of the mechanical models governed by tensile strain in the control section. This indicates that the structural system or the support conditions can have an influence on the shear strength of wide members without shear reinforcement commonly neglected. In this paper, we investigate the influence of the structural system on the shear strength of wide members. For this purpose, we review the available test results that varied the structural system, and we compared the accuracy and precision level of shear strength models from the literature according to the structural system of the members. In the analyses, we observed that the ratio of tested to predicted shear capacity is 5 – 10 % smaller for cantilever members than for simply supported beams. On the other hand, the ratio of tested to predicted shear capacity is on average 10-20% larger in continuous members than in simply supported ones. Although these results may indicate some influence of the structural system in the shear behavior, in this study, we did not identify physical reasons to validate this hypothesis. In this way, this tendency of results could be addressed to some bias in the database. However, we verified that the correlation between the shear capacities of wide members could be better correlated with the shear slenderness by taking into account that the behavior of some continuous members under uniformly distributed loads is similar to the simply supported ones with a reduced span length.
...
Most models of shear strength used to estimate the shear capacity of wide reinforced concrete members without shear reinforcement do not take into account the structural system or the support conditions. However, some experimental results indicate that bending moment can have a positive influence on members with predominant flexural action, contrary to most of the mechanical models governed by tensile strain in the control section. This indicates that the structural system or the support conditions can have an influence on the shear strength of wide members without shear reinforcement commonly neglected. In this paper, we investigate the influence of the structural system on the shear strength of wide members. For this purpose, we review the available test results that varied the structural system, and we compared the accuracy and precision level of shear strength models from the literature according to the structural system of the members. In the analyses, we observed that the ratio of tested to predicted shear capacity is 5 – 10 % smaller for cantilever members than for simply supported beams. On the other hand, the ratio of tested to predicted shear capacity is on average 10-20% larger in continuous members than in simply supported ones. Although these results may indicate some influence of the structural system in the shear behavior, in this study, we did not identify physical reasons to validate this hypothesis. In this way, this tendency of results could be addressed to some bias in the database. However, we verified that the correlation between the shear capacities of wide members could be better correlated with the shear slenderness by taking into account that the behavior of some continuous members under uniformly distributed loads is similar to the simply supported ones with a reduced span length.