Effect of Various Structural Factors on Shear Strength Degradation after Yielding of RC Members under Cyclic Loads

Abstract

Shear failure after flexural yielding is a typical failure mode for a reinforced concrete (RC) member subject to cyclic load, and it is caused by the phenomenon that the initial shear strength is decreased with the increasing plastic ductility until the shear capacity degrades to be lower than the flexural strength. In this study, the flexure-shear behaviors of a number of RC columns with a relatively wide range of crucial structural factors involving tensile reinforcement ratio, shear reinforcement ratio, shear span-depth ratio (covering deep and slender columns) and axial compression load were simulated by the Three Dimensional Rigid-Body-Spring-Method, and the degradation behaviors of shear strength of all specimens were quantitatively evaluated to comprehend the effect of the structural factors. Moreover, the degradation behaviors of shear strength were decoupled into the degradation behaviors of shear resistance components (beam action, arch action, truss action, concrete contribution for beam action) to clarify the mechanism of shear failure after flexural yielding for the RC columns at various crucial structural factors. Consequently, the effect of crucial structural factors on the degradation behaviors of shear strength and shear resistance components were understood and it was concluded that the stepwise degradation of arch action was the dominant mechanism for the investigated structural factors for the shear failure after flexural yielding of RC column. This paper is an extended version in English from the authors' previous publication [

Analytical Study on the Effect of Different Shear Reinforcement Shapes on Shear Failure Behavior and Shear Resistance Mechanism of RC Beams

“…The analytical method used in this study is 3-D RBSM (Yamamoto et al 2008), which enables to directly express discontinuous behaviors of concrete, such as cracking and fracturing. It has been verified by several studies that this method can reproduce the crack propagation and shear failure behavior of RC members with good accuracy (Yamamoto et al 2010(Yamamoto et al , 2014Gedik et al 2012;Fu et al 2017Fu et al , 2020Nakamura et al 2018).…”

“…It is known that the shear resistance mechanism of an RC member consists of beam and arch actions (Park et al 1975), and that these can be decoupled using analytical results obtained by 3D-RBSM (Fu et al 2017(Fu et al , 2020Nakamura et al 2018).…”

“…There are study cases in which these shear resistance mechanisms have been decoupled from the results of loading tests on RC beam specimens using reinforcement strain measurements (Kim et al 1999;Nakamura et al 2006;Yamada 2019;Gunawan et al 2020). On the other hand, it is possible to evaluate these mechanisms directly using numerical methods that allow visualization of stresses at specific positions (Fu et al 2017(Fu et al , 2020Nakamura et al 2018;Yamada 2019). Nakamura et al (2018) discussed the shear resistance mechanism of RC beams with shear reinforcements using a three-dimensional rigid-body spring model (3-D RBSM) (Yamamoto et al 2008), showing that it can evaluate the shear failure behavior of RC members with high accuracy.…”

Numerical Evaluation of Shear Strength Degradation Mechanism Dependent on the Size Increase of RC Deep Beams with Height up to 1.5 Meter by Using 3D Rigid-Body-Spring-Method

“…Discussion of the size effect mechanism on the shear strength of RC deep beams 5.1 Contributions of shear resistance components to the size effect 5.1.1 Decoupling method for shear resistance components It is a fundamental theory that the basic shear resistance components of an RC member consist of beam and arch actions. The decoupling method for beam and arch actions by using the numerical results of the 3D RBSM was applied and demonstrated by Fu et al (2017aFu et al ( , 2017bFu et al ( , 2020 and . This section describes the basic concepts of the decoupling method.…”

“…Obviously, the decoupling clarifies the dominant shear resistance component at each loading stage and the specific contributions of concrete and stirrups, together with the development of cracks. It is recognized that this kind of approach is very effective to evaluate the shear resistance components of RC members Yamada 2019;Gunawan et al 2020;Fu et al 2020).…”