Fundamental period of vibration for seismic design of concrete shear wall buildings

A simple expression is proposed to estimate the fundamental period of vibration for concrete shear wall buildings. Most seismic codes specify empirical period formulas for seismic design. In this study, fundamental period data for concrete shear wall buildings recorded during California earthquakes between 1971 and 1994 were compared with current US code formulas. It is shown that these formulas are inadequate for estimation of the fundamental period of concrete shear wall buildings. A closed-form period solution based on Rayleigh''s method, using shear wall displacement as a parameter, is proposed to estimate the fundamental period of concrete shear wall buildings in low-, moderate-, and high-seismicity regions. The accuracy of the closed-form solution is verified using recorded periods and confirms that the proposed expression provides reasonable estimates of the lower bound of a period. The results show that the fundamental period of concrete shear wall buildings depends significantly on the displacement and mechanical properties of the shear walls.