Seismic displacement demand prediction in non-linear domain: Optimization of the N2 method

作     者：Lorenzo Diana Andrea Manno Pierino Lestuzzi 

作者机构：EPFL – ENAC – IIC – IMAC DEIBPolitecnico di Milano 

出 版 物：《Earthquake Engineering and Engineering Vibration》 (地震工程与工程振动（英文刊）)

年 卷 期：2019年第18卷第1期

页      面：141-158页

核心收录：

学科分类：081405[工学-防灾减灾工程及防护工程] 08[工学] 0818[工学-地质资源与地质工程] 0815[工学-水利工程] 0813[工学-建筑学] 0802[工学-机械工程] 0814[工学-土木工程] 0801[工学-力学（可授工学、理学学位）] 

主　　题：N2 method seismic vulnerability assessment non-linear time-history analysis spectrum compatible recordings displacement demand determination optimization strength reduction factor 

摘      要：In Europe, computation of displacement demand for seismic assessment of existing buildings is essentially based on a simplified formulation of the N2 method as prescribed by Eurocode 8(EC8). However, a lack of accuracy of the N2 method in certain conditions has been pointed out by several studies. This paper addresses the assessment of effectiveness of the N2 method in seismic displacement demand determination in non-linear domain. The objective of this work is to investigate the accuracy of the N2 method through comparison with displacement demands computed using non-linear timehistory analysis(NLTHA). Results show that the original N2 method may lead to overestimation or underestimation of displacement demand predictions. This may affect results of mechanical model-based assessment of seismic vulnerability at an urban scale. Hence, the second part of this paper addresses an improvement of the N2 method formula by empirical evaluation of NLTHA results based on EC8 ground-classes. This task is formulated as a mathematical programming problem in which coefficients are obtained by minimizing the overall discrepancy between NLTHA and modified formula results. Various settings of the mathematical programming problem have been solved using a global optimization metaheuristic. An extensive comparison between the original N2 method formulation and optimized formulae highlights benefits of the strategy.