单向预应力混凝土空间框架弹塑性时程分析
Elastoplastic time history analysis of unidirectional prestressed concrete space frame

参照中国现行结构设计规范，按不同抗震等级设计4个处于结构临界高度（24 m）和临界跨度（18 m）的7度二、三级和8度一、二级单向预应力空间框架（一级框架中柱"强柱弱梁"级差调整按建议公式弱化设计），然后基于OpenSEES有限元分析平台，进行双向地震动下的弹塑性时程分析，研究其在罕遇地震下的抗震性能和能力。结果表明：各框架沿两个方向屈服程度均不高、具有较好的整体抗震能力。其中，取较低抗震等级的7度三级和8度二级框架，其整体地震反应较取较高抗震等级的7度二级和8度一级框架略大，但差异并不明显。RC框架方向形成理想的"梁铰机制"，PC框架方向形成"柱铰机制"，PC框架抗侧刚度更大、抗震能力更强。抗震等级为一级的PC框架经弱化中柱设计后，可以有效引导框架在中柱出铰，但仍不能避免边柱少量出铰，可考虑适当加强边柱予以控制。
Four unidirectional prestressed space frames set at the critical height (24 m) and the critical span (18 m) were designed according to the Chinese codes, including two frames of the second, third seismic grade in intensity-category seven and two frames of the first, second seismic grade in intensity-category eight ("strong column-weak beam" in the middle nodes of the first seismic grade frame was weakened by the suggested method), based on the OpenSEES framework, elastoplastic time history analysis method was used to analyze the structural seismic performance and capacity under the bi-directional seismic waves. The results showed the yielding degree of every frames in both directions was acceptable and the global seismic capability was good. Besides, the frames which took a lower seismic grade had a slightly larger global seismic response. but the difference was not obvious. An ideal "beam hinge mechanism" was formed in the direction of RC frames and a "column hinge mechanism" was formed in the direction of PC frames, the lateral stiffness and seismic capability of PC frames were better than RC frames'. The PC frame of the first seismic grade formed hinges in middle columns effectively after weakening "Strong Column-Weak Beam", but hinges in side columns were still unavoidable, thus it was considerable to strengthen side columns.