Abstract
Moment-independent importance (MII) analysis is known as a global sensitivity measurement in qualifying the influence of uncertainties, which is taken as a crucial step towards seismic performance analysis. Most MII analysis is based on Monte Carlo simulation, which leads to a high computational cost since a large number of nonlinear time history analyses are required to obtain the probability density function. To address this limitation, this study presents a computational efficient MII analysis to investigate the uncertain parameters in the seismic demands of bridges. A modified four-point-estimate method is derived from Rosenblueth’s two-point-estimate method. Thus, the statistical moments of a bridge’s seismic demands can be obtained by several sampling points and their weights. Then, the shifted generalized lognormal distribution method is adopted to estimate the unconditional and conditional probability density functions of seismic demands, which are used for the MII analysis. The analysis of seismic demands based on piers and bearings in a finite element model of a continuous girder bridge is taken as a validation example. The MII measures of the uncertain parameters are estimated by just several nonlinear time history analyses at the point-estimate sampling points, and the results by the proposed method are compared with those found by Monte Carlo simulation.
Highlights
The aforementioned studies on the global sensitivity analysis of uncertain parameters to seismic demands are based on sampling-based methods such as Monte Carlo (MC) simulation or Sobol sequences, which require a large number of nonlinear time history analyses (NTHA) of structural models because the global sensitivity index evaluation involves a double loop simulation to propagate the uncertainties for evaluation of the unconditional and the conditional probability density function (PDF) of seismic demands
The modified 4PEM combined with the shifted generalized lognormal distribution (SGLD) method are applied to Moment-independent importance (MII) analysis on the global sensitivity of the uncertain structural parameters on seismic demand for a bridge structure model
MII analysis based on the combination of a modified 4PEM and SGLD is first carried out in this research to analyze the global sensitivities of the uncertain structural parameters to a bridge’s seismic demand parameters
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Applied the MII and variance importance methods to analyse the sensitivity of uncertain parameters involved in the seismic demands of bridge structures by MC simulations and kernel density estimation, respectively [11]. The aforementioned studies on the global sensitivity analysis of uncertain parameters to seismic demands are based on sampling-based methods such as MC simulation or Sobol sequences, which require a large number of NTHA of structural models because the global sensitivity index evaluation involves a double loop simulation to propagate the uncertainties for evaluation of the unconditional and the conditional probability density function (PDF) of seismic demands. The modified 4PEM combined with the SGLD method are applied to MII analysis on the global sensitivity of the uncertain structural parameters on seismic demand for a bridge structure model. The contents of this paper are divided as follows: In Section 2, the derivation of the proposed efficient MII method is addressed, in which the equations of the MII index are demonstrated in Section 2.1, a modified 4PEM is derived in Section 2.2, the modified
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