特殊中心支撑钢框架非耗能构件抗震承载力需求研究

Study on seismic capacity demands of non-dissipative members in special concentrically braced frames

中心支撑钢框架结构具有抗侧性能良好、经济效率高,目前,被广泛应用于多高层钢结构工业和民用建筑当中.支撑是其耗能和抗侧力构件,并且支撑承受的水平地震作用主要以轴力形式传递给支撑跨梁和柱.当遭遇罕遇地震时,支撑发生屈曲或屈服,由于内力重分布使得支撑跨梁和柱内力增大许多,因此,支撑跨梁和柱必须具有足够的强度和刚度,才能保证在罕遇地震下的需求,否则极易导致整体结构承载力及刚度迅速下降,形成薄弱层,进而引起倒塌.本文通过有限元模拟进行非线性时程分析,研究中心支撑钢框架结构的罕遇地震作用效应.针对现行规范对中心支撑钢框架结构设计的相关规定,探究房屋层数、设防烈度和设计应力比等因素对非耗能构件承载力需求的影响规律,提出非耗能构件弹塑性阶段的补充设计方法.

The concentrically braced steel frame structure has been widely used in multi-storey and high-rise steel structures because of good seismic resistance performance and economical efficiency,light weight and high strength of steel material.As energy dissipation element,the bracing resists seismic lateral force under axial force transmitting to beam and columns.When the bracing buckles or yields under severe earthquake,the demands of beams and columns will increase greatly due to the redistribution of forces.Therefore,beams and columns must have sufficient strength and stiffness to ensure the demand under severe earthquakes,otherwise it is very easy to cause overall structural collapse with rapid decline of stiffness and appearance of weak story.Based on the finite element simulation of nonlinear time history analysis,the dynamic earthquake response process of centrically braced steel frame is showed,and the effects of different conditions on the demands of columns and beams are studied.Since some studies have exposed the inadequacy of the design regulations about non-dissipative components of centrically braced steel frame structure in the current code,supplementary design methods are proposed.