装配式钢-混凝土组合框架动态倒塌性能研究

Study on Dynamic Collapse Performance of Prefabricated Steel-Concrete Composite Frame Structures

装配式钢-混凝土组合框架在工程中的应用日益增多,但是目前有关其抗倒塌性能的研究鲜见报道。为了研究装配式钢-混凝土组合框架的动态倒塌性能,文中首先设计了2个缩尺的装配式组合框架子结构试件,对其开展了动态抽柱试验,研究了此类框架结构在不同倒塌荷载工况下的动态倒塌行为,并评估预制混凝土板分段对框架动态倒塌行为的影响;然后,基于试验结果建立了装配式组合框架倒塌荷载等效动力增大系数DIF的计算模型。结果表明:在1倍倒塌荷载(30 kN)和2倍倒塌荷载(60 kN)的作用下,装配式钢-混凝土组合框架子结构的主要损伤为靠近边柱的框架梁端混凝土板的开裂;中柱失效后,剩余子结构仍具有较好的承载能力和整体刚度,在这两种工况下结构不会发生倒塌破坏;在相同倒塌荷载作用下,装配式组合梁框架受到的冲击效应大于现浇混凝土组合梁框架;混凝土板分段预制对组合框架子结构的基本动力特性影响不大,但会导致组合梁端钢梁应变和预制混凝土板中纵向钢筋应变的动力增大系数变大;2个试件失效柱位移动力增大系数介于1.38~1.65之间,在部分情况下应变的动力增大系数大于2.0;基于试验结果建立的装配式组合框架倒塌荷载等效动力增大系数DIF的计算模型可为开展装配式组合框架静力倒塌分析时倒塌荷载的修正提供参考,基于该模型得到的倒塌荷载DIF计算值偏于保守。

Prefabricated steel-concrete composite frames are increasingly applied in engineering day by day.However,research on their anti-collapse performance is less reported.To investigate their dynamic collapse perfor-mance,two reduced-scale prefabricated composite frame substructures were designed and tested by dynamically removing a column in this paper.Collapse behaviors of such frame structures under different load conditions were studied,and the effect of the division of precast concrete(PC)slabs on the dynamic collapse behaviors was also assessed.Then,a calculation model of the equivalent dynamic increase factor(DIF)of collapse load was built based on the experimental results for prefabricated composite frames.The results show that under the effects of one time collapse load(30 kN)and twice collapse load(60 kN),the primary structural damage for prefabricated steel-concrete frame substructures is the cracking of concrete slab at the beam ends close to the side column.After the middle column failed,the residual structures still have the superior load-bearing capacity and overall stiffness.The structures will not collapse under the two load conditions.The prefabricated composite frames are subjected to a greater impact effect under the same collapse load compared to the composite frames using cast-in-situ concrete.Division of the PC slabs slightly affect the dynamic characteristics of the composite frame substructures.However,it will lead to the increase of the strain dynamic increase factors of the steel girders and the longitudinal slab reinforcement.The increase factors of vertical displacement at the failed columns vary between 1.38 and 1.65 for the two substructures,and the dynamic increase factors of strain are even greater than 2.0 in some cases.The calculation model of the equivalent DIFs of collapse load for prefabricated composite frames developed based on the experimental results can provide a reference for the revision of the collapse load when the static collapse analysis is conducted.The calculated DIF of collapse load based on this model is conservative.