Computer modeling and effective stiffness of concrete wall buildings

Shake-table tests of a full-scale seven-story wall structure at the University of California at San Diego (UCSD) provide a crucial benchmark in evaluating methods that are currently being used to design mid-rise and high-rise concrete buildings in seismically active areas. The authors compare properties and characteristics of the UCSD test structure with twelve tall concrete core-wall buildings that have recently been designed for the western United States, and find that the test results are applicable to this type of structure. Using assumptions, methods, and software that are typical in design practice, the authors constructed linear and non-linear computer analysis models of the UCSD test structure. Iterations of assumptions for the linear models lead to recommended concrete stiffness properties, which are then compared to published recommendations that are often used in design. Recommended stiffness properties are lower than those commonly used in practice. Comparison of the non-linear models to test results shows a difficulty in matching building deformations while also matching overturning moments and shear forces. Both types of models show a significant influence of slabs engaging columns, and acting as outriggers, increasing overturning resistance and shear demand on the wall.