Investigation of Stiffness Effect of Coupling Beam on Boundary Element Detailing in Structures with Hybrid Coupled Shear Walls

Abstract

Coupled walls are known to be efficient lateral load-bearing systems. Coupling beam and wall piers are two important and effective elements in the general response of these structures. In this paper, stiffness effect of steel coupling beams on boundary elements in coupled shear walls has been investigated. The provisions of Iranian National Building Code for concrete structure (INBC-No. 9) for evaluating detailing requirements at wall boundaries are based on studies on uncoupled continuous walls, in which stress distribution across sections is assumed to be linear and in un-cracked sections. Due to the fact that there have been severe axial forces on wall piers resulting in the creation of cracks in sections of tension walls, the applicability of these provisions in coupled walls should be evaluated. Several coupled wall structures with different geometrical specifications, representative of various ratios of stiffness of the coupling beam to stiffness of the wall (RSBW), under equivalent lateral force, were designed, and efficiency of the code provisions was investigated in comparison with the results of the numerical analysis in Abaqus software. In this analysis, nonlinear behavior of material was considered. Results show that for structures with large and medium RSBW, code provisions are not appropriate in evaluating detailing requirements of tension wall boundaries, and a nonlinear stress distribution on the section should be used. For compression walls and structures with low RSBW, code provision is reliable.