屈曲约束支撑式延性桁框结构探讨

Study on special truss moment frames with buckling restrained braces

在桁框结构的桁架跨中央设置屈曲约束支撑式消能段是一种新型的延性桁框结构。针对该结构体系,首先推导消能段的极限抗剪承载力,然后提出结构简化计算模型,并根据我国抗震设计准则给出确定屈曲约束支撑设计承载力的计算方法和构造要求。采用本方法确定的消能段可以精确控制延性桁框结构的屈服时刻和破坏模式,并实现水平地震作用下各楼层同步屈服,充分耗能。最后采用有限元方法进行单向和循环加载分析与验证,结果表明:合理的屈曲约束支撑承载力可以显著提高延性桁框结构的延性、耗能能力、承载能力和安全储备,抗震性能明显优于普通桁框结构;该计算方法具有较高的精度,可以在确保消能段耗能的前提下实现结构的优化设计。

To set energy dissipation segment with buckling restrained braces in the midspan of truss moment frames is a new type of the special truss moment frames. The ultimate shear bearing capacity of energy dissipation segment is derived firstly, and then the calculation model of structures, the method to determine the design value of bearing capacity of buckling restrained brace and detailing requirements are presented. The proposed method can accurately control the yielding time and failure mode of special truss moment frames and achieve the objective that all floor yield simultaneously under the horizontal earthquake and energy may be dissipated fully. Eventually, the monotonic and cyclic tests are conducted and evaluated using finite element method. Results show that reasonable bearing capacity of buckling restrained brace may significantly enhance the ductility, energy dissipation capacity, load carrying capacity and safety margin of special truss moment frames, and its seismic behavior is apparently superior to ordinary truss moment frames. This proposed method is a high precision approach, and it may lead to the structure optimization design under the premise of ensuring energy consumption of energy dissipation segment.