Verification of multi‐degree‐of‐freedom building modelling for seismic response prediction based on microtremor measurement

Abstract

The applicability of the proposed dynamic response model for buildings is investigated using shaking-table tests with a four-storey steel specimen. This approach derives the equation of motion for a multi-degree-of-freedom linear building based on microtremor measurements. Under a linear assumption, the equation can estimate the seismic response accelerations, velocities, and displacements at microtremor sensor locations without the need for information about the mass, damping, stiffness matrices or need for structural design documents to estimate peak responses that are linked with seismic damages of structural and non-structural components. The modelling is unconstrained by structural shape, composition of frames, connections of structural members, or the assumption of a rigid floor. In comparison to the previous methods assuming simple/regular building shape with standard/typical rigid floor, the proposed model is applicable to large-scale low-rise buildings with irregular shapes, flat expanses, and open spaces such as large atria and skylights as well. The applicability study considers two practical scenarios: natural frequencies and damping ratios based on microtremors that can be updated by an earthquake and a standard assumption for structural design. The prediction accuracy is best when the participation vector for seismic input is obtained from sensors located on the upper floors; the structure mostly exhibits elastic response; a modal system identification is applied to the seismic measurement; and local damage does not affect the global seismic response of the structure. The reason is that this method assumes that identified mode shapes do not change due to the occurrence of an earthquake.