中文摘要：

首都机场航站楼（T3）下部为混凝土和钢混合框架，上部为复杂的双曲面形双层扁网壳，长960m，宽780m，为超大体量大跨度复杂空间钢结构体系。本文采用SAP2000有限元软件，对其进行了单维和多维地震输入下的反应谱分析，研究了单维和多维地震输入对构件内力、节点位移和地震总剪力的影响；研究了多维地震输入下地震响应值与按规范地震组合公式计算所得地震响应值的关系；研究了模态提取数目和质量参与系数的关系，CQC法中参与组合的模态数目与结构地震响应的关系。研究表明，采用振型分解反应谱法时，模态频率越高，对结构内力的影响越小，对于对结构影响较小的高频模态，可以忽略其对结构的影响；根据单维和多维地震反应的对比分析，对超大跨度复杂钢结构宜进行三维地震输入的反应谱分析。另外，本文提出了一种新的地震效应组合方法．可替代多维地震反应分析，并弥补现行规范的不足。

英文摘要：

The terminal building of Beijing Capital Airport （＇I3）, a super large long-span complex spacial steel structure, is made up of steel frame and double-layer reticulated shell, which is 960m long and 780m wide. Response spectrum analysis is conducted for it by using SAP2000 finite element software. The influences of one-dim ensional and multi-dimensional earthquake input on the element force, the joint displacement and the total earth- quake shearing force are analyzed. The relationship between seismic response under multi-dimensional earthquake input and that calculated by Chinese Earthquake Criterion combination formula is studied. The relationship between the number of modes and modal participating mass ratio, and the relationship between the number of modes used in CQC method and the seismic response of structure are investigated. These researches show that the influence of high frequency modes on the structure internal force is little and could be ignored. According to the comparison befween the seismic response under one-dimensional and multi-dimensional earthquake input, the response spectrum analysis under multi-dimensional earthquake input should be conducted for the super large long-span complex spacial steel structure. In addition, this paper provides a new method of earthquake combination, which can substitute the multi-dimensional earthquake analysis and make up the deficiencies of the current specifications.