国家博物馆老馆(Ⅶ甲段)加固前后抗震性能对比分析

Comparative of seismic performance for the unstrengthened/strengthened block Ⅶa in the old National Museum

国家博物馆老馆是由原中国革命博物馆(甲区)和中国历史博物馆(乙区)合并而成,共分23个区段,即共由23个单体建筑组成。此次改扩建结合建筑总体功能布局要求,拆除Ⅰ～Ⅵ区,保留Ⅶ～Ⅺ区及Ⅻ,ⅩⅢ廊区。原结构均为钢筋混凝土柔性框架结构,各区段间从基础到屋顶层均设置了100mm的变形缝,基础则根据结构(横向两边跨小、中间跨大)特点,采用的是沿纵向两边跨条形联合基础。由《中国国家博物馆检验报告》可知:梁、板开裂较多,裂缝最大宽度梁为1.5mm、板为2.3mm,并有少数地方出现露筋现象;抗震验算表明:原结构在8度多遇地震作用下远不能满足国家有关规范要求,必须进行加固。结构加固设计,针对各区段不同情况,运用结构综合抗震能力分析方法和多种最新加固手段,在保持原有建筑风貌的前提下,实现了提高结构抗震能力和改善使用功能的协调。采用非线性动力时程分析方法,分析了其中一个区段(Ⅶ甲区)在罕遇地震输入下结构的弹塑性响应,对比研究了结构在加固前后的弹塑性抗震性能,为工程设计提供了参考。

The old National Museum of China was composed of the Museum of Chinese Revolution and the Museum of Chinese History,which altogether composed by 23 blocks.Consulting the requirement of the architectural layout,this rebuild and extend project dismantled block Ⅰ ～ Ⅳ,and retains block Ⅵ ～ Ⅺ,Ⅻ,ⅩⅢ.All blocks of the old museum are reinforced concrete frame structure,which deformation joints set in each block from strip foundation to roof are width of 100mm.The inspection report of the National Museum of China indicated that there were many cracks in beams and boards of the building.The biggest crack is 1.5mm in the beam and 2.3mm in the floor,even rebars can be seen in several places.The seismic calculation indicated that under 8 degree frequent earthquake,the safety reliability of several parts are very low and canot satisfy the requirements of national currently code.In the structural strengthening design,the ways of analyzing synthetical anti-seismic capability and several new strengthened methods are used successfully.In that way,the original construction styles are contained,the anti-seismic capability is enhanced and the use function is improved simultaneously.The elasto-plastic response under rarely earthquake in the block Ⅶ a is studied with the method of nonlinear dynamic history analysis.The analysis results have been used in the structure design.