Soil and Structural Nonlinear Inelastic Effects on the Seismic Response of Tall Buildings: Fid-Bau Portal

Soil and Structural Nonlinear Inelastic Effects on the Seismic Response of Tall Buildings

Mercado, Jaime A. / Arboleda-Monsalve, Luis G. / Mackie, Kevin

Soils and structures can undergo inelastic demands during an earthquake event; thus soil-structure interaction (SSI) effects are of interest for the seismic analysis and design of tall buildings on shallow foundations. Oversimplifying soil and structural modeling using linear-elastic approaches introduces variability and biases in the computed seismic response of buildings. Engineering demand parameters (EDPs) from coupled SSI systems can only be realistically determined when nonlinearities in the constitutive soil and structural behaviors are accounted for explicitly in the numerical formulation. The objective of this paper is to evaluate numerically the interaction of a nonlinear soil-structure system using a direct fully-coupled approach. Nonlinear-inelastic numerical analyses are conducted on an archetype 30-story building which is supported on a mat foundation modeled using nonlinear link elements to control stiffness and strength. Large discrepancies occur between linear and nonlinear-inelastic tall building modeling approaches mainly in terms of structural demands (i.e., horizontal displacements, accelerations, and drifts), foundation rotation, and soil settlements. The nonlinear-inelastic analyses show a significant decrease of the seismic demands when compared to those computed using linear-elastic SSI models. More realistic computed responses are obtained when nonlinear-degrading building models including SSI effects are used since the energy distribution and tradeoff among both supporting soils and structure vary significantly as a function of the seismic demands.