Quantifying the influence of modeling uncertainties on performance evaluation of mega column-core tube-outrigger structure under near-field and far-field ground motions

Abstract

Different types of ground motions have the potential to aggravate the failure state of mega column-core tube-outrigger structure(MCCTOS) considering uncertainty. It is of great engineering significance to comprehensively analyze the seismic fragility of the structure under different types of ground motions. The purpose of this work is to analyze and predict the impact of modeling uncertainties on the performance evaluation of MCCTOS under different types of ground motions and determine the sensitivity of independent input parameters. On the premise of considering both seismic uncertainty and structural uncertainty, the Latin hypercube sampling and first-order second-moment, which are respectively combined with incremental dynamic analysis, are adopted to perform seismic fragility analyses of MCCTOS. By comparing the fragility curves of MCCTOS under non-pulse near-field ground motions, pulse-type near-field ground motions, and far-field ground motions, the influence of the randomness of earthquakes and structural parameters on the fragility of MCCTOS under different types of ground motions is analyzed. In addition, the seismic damage index is introduced into the fragility assessment of MCCTOS. By combining the seismic damage index with the beta distribution function, the matrix and probability density function of the seismic damage index of MCCTOS are established. Furthermore, the influence of structural parameter uncertainty on the seismic damage index of MCCTOS under different types of ground motions is investigated. The sensitivity analysis of uncertain parameters in the MCCTOS is carried out by using tornado analysis technology and Sobol' method to investigate the influence of the considered parameters on the seismic response of MCCTOS. The results show that pulse-type near-field ground motions are easier to cause structural damage than non-pulse near-field ground motions and far-field ground motions. However, for the MCCTOS under the non-pulse near-field ground motions, the modeling uncertainties have the greatest impact on the seismic capacity and lead to the maximum reduction of the average seismic damage index. The structural responses are found to be most sensitive to the density of concrete, compressive strength of concrete, and structural damping ratio.