Shear Strength Prediction of Reinforced Concrete Walls with Opening and Boundary Elements

Abstract

Reinforced concrete (RC) walls containing openings are usually stiffened by boundary elements (or boundary flanges) in the form of columns on one or both sides. Both thickness and longitudinal reinforcement ratio of such boundary members generally exceed those of enclosed walls. Such boundary elements also contribute to an improvement in the strength of enclosed walls. As a result, the strength of RC walls with openings with boundary elements is higher than those without them. In this paper, an analytical approach based on the softened strut-and-tie model is proposed to evaluate the shear strength of RC walls with a central opening and enclosed by boundary elements. The combined behavior of the wall and boundary elements under a simultaneous bending moment and axial loading is considered in the sectional analysis to calculate neutral axis depth for evaluating strut capacity. Shear strength predictions through the proposed approach showed reasonable accuracy when verified against the test data from eleven RC walls with a single central opening. Comparisons are also made with strength estimations based on American and Japanese code provisions. Finally, a simplified equation for the evaluation of neutral axis depth is presented to enable design engineers to conduct preliminary design of RC walls with openings that are enclosed by boundary elements.