System identification, finite element modeling and model updating of a building incorporating soil flexibility and non-structural components

In this study, system identification and finite element modeling of a four storey instrumented building is described. The reinforced concrete building has five tri-axial accelerometers to measure its response during seismic events. Subspace state-space system identification technique was used to extract dynamic properties including natural frequencies, damping ratios and mode shapes using recorded seismic responses. A three-dimensional finite element model of the building was developed to extract theoretical modal properties. To simulate real in-situ conditions, soil underneath the foundation and surrounding the basement was modeled using spring and dashpot elements and non-structural components (NSCs), such as cladding and partition walls, were also included. To evaluate the effect of soil and NSCs in dynamic response, a series of finite element models were constructed, viz. bare fixed-ended frame, frame with floor slabs, stairs, shear walls, NSCs and finally soil flexibility included. It was concluded from the investigation that the effect of soil and NSCs is significant towards the dynamic response of the building and these should be considered in models to simulate the real behavior.