摘要
钢结构轻质高强,抗震性能好。纯钢框架侧向刚度较差,往往需要较大的梁、柱截面才能满足要求,中心支撑钢框架的支撑在强震作用下易发生屈曲失稳,造成其抗震能力急剧下降,偏心支撑钢框架的支撑在一定程度上解决了上述结构体系中存在的问题,但在强震下仍有支撑屈曲、拉压滞回性能不对称等问题。为了改善支撑的受力性能,使其在地震作用时不发生屈曲,屈曲约束支撑钢框架体系应运而生。这种体系在发达国家已被大量采用,国内的应用研究正在不断发展中。
本文首先应用ANSYS有限元分析软件对屈曲约束支撑钢框架和普通支撑钢框架在静力往复荷载作用下的受力性能进行模拟。结果表明,屈曲约束支撑钢框架滞回曲线较普通支撑钢框架滞回曲线更加饱满,滞回环包含的面积相对较大,说明其能够消耗更多的能量,具有更强的耗能能力。通过对屈曲约束支撑钢框架和普通支撑钢框架进行时程分析,对比了两种体系大、小震的时程响应,得出屈曲约束支撑钢框架具有更好的抗震性能。
基于增量动力分析,求出多条地震波下的结构基底剪力和顶点位移,并进行多项式拟合,得到结构的IDA能力曲线;以此为基础,研究了层数和跨数对屈曲约束支撑钢框架结构影响系数的影响。结果表明,层数和跨数的影响很小,可以忽略不计,结构影响系数R中结构超强系数所占的比重明显大于结构延性系数。
The steel structure is light-weight and high-strength and have good seismic performance. The beam and column sections of non-braced steel frame are usually amplified to satisfy the lateral displacement because of its flexible lateral stiffness.The center-brace is always buckling under strong earthquake which makes the lateral stiffness and dissipation ability of the frame fall down rapidly.The eccentric-braced flame has resolved the problems appearing on above-mentioned structures to a certain extent but the eccentric-brace is still buckling under massive earthquake and have an asymmetric hysteretic behavior under tension and compression.In order to improve mechanical performance of brace, a new system called buckling restrained braced steel frame is put forward, This system has been adopt in developed nations and domestic application research is in continuous evolution.
At first,the buckling restrained braced steel frame and ordinary concentrically braced steel frame are simulated adopting ANSYS in this paper. The results show that hysteretic curve of buckling braced steel frame is plumper than conventional concentrically braced steel frame. The area of hysteretic loop is bigger, which indicate that it can dissipate much more energy, and has more strong energy-dissipating capacity.Time history analysis was performed on the buckling restrained braced steel frame and ordinary concentrically braced steel frame, time-history response on the big and small earthquake of the two systems are contrasted. It shows that seismic behavior of buckling restrained braced steel frame is better.
Based on incremental dynamic analysis, structure base shear and top displacement are calculated and polynomially fitted, and the IDA ability curve is obtained,based on which, the influence of the number of story and span to structural influencing coefficient of buckling restrained braced steel frame is researched. The analysis shows that the influence of the number of story and span is so small that it can be neglected . The proportion of over-strength coefficient of structure in the structural influencing coefficient R is much bigger than that of ductility coefficient.
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