Behavior‐Based Method to Determine Design Shear in Earthquake‐Resistant Walls

Abstract

For earthquake‐resistant design of reinforced concrete structures, the shear force for frame elements is established on the basis of the proportions and flexural strength of the element according to the American Concrete Institute Standard 318‐89 (1989), the Applied Technology Council Standard 3‐06 (1989); and the Uniform Building Code, published in 1988. In this paper, a similar procedure is proposed for walls in medium‐rise, reinforced concrete buildings. Results of small‐scale dynamic tests of nine‐ and ten‐story structures with walls are presented to provide data with which to evaluate methods of estimating base shear. Maximum base‐shear response during these tests consistently exceeded limit analysis estimates calculated assuming a linearly varying acceleration distribution. If the observed force distribution is used in estimating base shear, the limit analysis estimates are acceptable. The need to take into account variations of inertial force distribution with base‐motion intensity is supported by experimentally observed behavior, by modal analysis, and by nonlinear response‐history analysis. After discussing other factors that influence maximum base shear, such as strain rate, strain hardening, and systematic experimental error, a design procedure for estimating shear demand for walls that reflects observed behavior is proposed.