基于水平单向偏心结构的二维MPA方法

目前结构性态评估方法的研究基本都是以单自由度体系和单向地震动输入为前提的，而实际地震动的多维性、结构的空间耦合特性使目前基于单自由度体系的结构性态评估方法存在较大的局限性。本文在对水平偏心结构模态分析的基础上，建立了单向水平偏心结构的等效二自由度模型（EDDOF），用以表征单向非对称结构体系的平扭耦联效应。然后对EDDOF体系进行了振动特性分析，在验证EDDOF模型正确性的基础上，提出了二维MPA方法（2DMPA），并通过一个偏心钢框架结构算例验证了2DMPA方法的正确性。结果表明：本文提出的二维MPA方法可以精确描述单向非对称结构的弹性地震反应，在非弹性情况下的精度较高，可用于偏心结构的性态评估。

A Two-Dimensional Modal Pushover Analysis Procedure for Horizontal Asymmetric Structures

At present, the simplified methods for evaluating the structural seismic response are mostly based on the single degree of freedom system (SDOF) and unidirectional seismic excitation. However, most of existing simplified method is not adequate for the asymmetric structures because of the multi-dimensional ground motions and the spatial coupled effects of structural characteristics. Considering asymmetric and coupled characteristics of structures, a modal equivalent double degrees of freedom (EDDOF) system, based on the modal analysis, is presented with eccentric mass, rigid bars and springs. Then a two-dimensional modal pushover analysis (2DMPA) procedure is developed based on the EDDOF system. In order to verify the method, the lateral and rotational 2DMPA and the nonlinear time history analysis (NTHA) is performed on an asymmetric steel frame structure. The results show that the 2DMPA procedure is reliable and effective for evaluating the seismic response of structures.