Impact of Seismic Rotational Components on Symmetric Structures

Abstract

This chapter focuses on studying the impact of the rotational components of seismic excitation on different styles of buildings. The rotational components are synthesized from the translational components of the 2008 Wenchuan earthquake recorded at Mianzhu station. The analysis results show that the rotational components cause much larger torque in a symmetric structure than the translational components. The total seismic responses are comprised of the responses caused by the rotational components and the responses caused by the translational components. For a 30-m-tall symmetric building, the rotational components contribute about 10% of the total seismic responses. For a high-rise building, the rotational components can cause about 50% of the total responses, but for 160-m-high structure, when the rotational components are added, the responses increase by a much smaller level than that caused by the rotational components alone; for 443-m-high building, the responses caused by the translational components and by the rotational components can be directly added together. It implies that the rotational components effect on the structure may be closely related to the structure height. This chapter uses Eurocode8 and ANSYS method to analyze the model, and the results show that Eurocode8 might overrate the seismic rotational loads in some cases.