鉄筋コンクリート部材に関する従来型曲げせん断変形分解法の力学的意味と適用限界

Abstract

Researchers engaged in structural testings often decompose the deflection of a member into flexural and shearing components. The physical meaning of this decomposition, however, has not fully been discussed yet. Moreover, there are some disagreements among researchers as to the definition of flexural and shearing deformation. This paper firstly presents a mathematial and rigorous expression for the conventional definition of flexural and shearing deformation. The shearing component of deflection is defined as the factored average of the shearing strain within the member. The flexural component of deflection is defined as the factored integration of the curvature calculated from the axial strain of the edges of the member. In case of a framed shear wall where the peripheral beams and columns carry only the axial stresses and the web concrete and shear reinforcement in the wall carry only the shear stress, the shear-flexure decomposition technique has physical meanings as follow. (a) The hysteresis loop of load vs. shearing deformation relation represents the energy absorbed within the web concrete and shear reinforcement. (b) The hysteresis loop of load vs. flexural deformation relation represents the energy absorbed by the peripheral frame. In case of a beam or a column where the longitudinal reinforcement carry only the axial stresses and the web concrete and shear reinforcement carry only the shear stress, the shear-flexure decomposition technique has physical meanings as follow. (a) The hysteresis loop of load vs. shearing deformation relation represents the energy absorbed within the web concrete and shear reinforcement. (b) The hysteresis loop of load vs. flexural deformation relation represents the energy absorbed by the longitudinal reinforcement. Stress flow in truss action resembles the stress states stated above. Therefore, the hysteresis loops of load vs. flexural and shearing components of a truss-action-dominated member tend to have such physical meanings. In case of a member where an arch action dominates, however, these loops do not have such physical meanings. In this case, even a sliding deformation along a diagonal shear crack may be partly considered as a flexural deformation.