钢结构火电厂主厂房抗震性能评估

Seismic performance evaluation on steel frame thermal power plants main building

通常钢结构火电主厂房结构质量、刚度分布不均匀,不利于保证结构的抗震性能,且目前大多数钢结构主厂房只进行多遇地震作用下的承载力和变形验算,因此,有必要对此类结构在罕遇地震作用下的抗震性能进行分析。对典型钢结构主厂房的弹塑性时程分析发现,钢结构主厂房普遍存在罕遇地震作用下抗震性能不满足规范要求的情况。在分析其原因的基础上,根据每层柱、支撑的等效抗侧刚度比确定相应的优化方案,通过控制支撑的轴压比和柱的塑性强度使结构满足罕遇地震作用下的性能要求。通过两个算例验证了方案的有效性,该方案避免了复杂繁琐的弹塑性分析,可大幅提高结构设计效率,提出的方案也可为同类钢结构的抗震设计提供参考。

Steel frame thermal power plant main buildings are generally irregular in mass and stiffness,which eventually affects their seismic performance. Besides,for most steel main plants,the bearing capacity and deformation under frequent earthquake are usually checked only. Therefore,it is important to evaluate the seismic performance of main plants under rare seismic actions. Nonlinear time history analysis of typical main plants indicates that under rare earthquakes the seismic performance of most main plants cannot meet the requirement of present design codes. Based on qualitative reasoning,a control method was proposed according to the stiffness ratio of brace and column in each story in which the axial compression ratio of braces and the plastic strength of columns were limited to certain threshold to assure sufficient seismic performance of main plants under rare earthquakes. Two main plant models were used to verify the efficiency of the proposed method. It is indicated that the proposed method can save much design efficient by avoiding time-consuming nonlinear time history analysis. The research also provides useful reference for seismic design of similar structures.