考虑现浇板作用的钢筋混凝土框架结构抗连续倒塌性能试验

Experiment on anti-progressive collapse performance of RC space frame considering the effect of cast-in-place slabs

为研究带板钢筋混凝土框架结构抗竖向连续倒塌性能,设计了一榀1/3比例的2层两跨带板钢筋混凝土空间框架结构,并进行竖向连续倒塌拟静力试验。在柱顶施加集中荷载,采用控制位移的方式卸除边柱,模拟结构竖向倒塌过程,直至结构倒塌破坏,观测分析结构变形、梁板钢筋应变以及竖向抗力。研究结果表明:带板钢筋混凝土框架结构连续倒塌抗力先后由梁拱-板压膜机制、梁拱-板拉膜机制、梁悬索-板拉膜机制、板拉膜机制提供,结构极限抗力在结构外推-内收转换位移处出现;由于现浇板对框架梁上部的加强作用,在梁上部受压区混凝土发生严重压碎破坏前,梁下部受拉区钢筋已经拉断破坏,结构竖向抗力出现较大幅度下降;结构宏观变形经历了水平外推阶段、水平内收阶段和倒塌阶段,结构水平侧移最大值没有超过《建筑抗震设计规范》(GB 50011—2010)中框架柱的侧移限值,单根边柱失效不会引起相邻柱的连续破坏,最终结构倒塌由现浇板钢筋的拉断和脱锚控制;不利荷载主要通过与失效柱相连的梁和现浇板进行内力重分布,结构未与失效柱相连的梁出现了显著受扭破坏,板的拉膜作用使更多构件有效参与到抵抗结构的连续倒塌破坏过程中;框架梁破坏后现浇板仍能提供达极限荷载的84.9%的抗力,体现了现浇板对结构整体受力性能和变形能力的改善作用。

In order to study the anti-vertical progressive collapse performance of reinforced concrete frame with slab, a quasi-static vertical progressive collapse test was carried out on a 1/3 scale of two-storey by two-bay reinforced concrete frame structure. The concentrated load was applied in the top of the column. The side column was removed by controlling displacement. The vertical structure collapse process was simulated until structural collapse destroyed. The deformation and strain slab steel structure and vertical resistance were observed and analyzed. The results show that the progressive collapse resistance of reinforced concrete with slab is provided by the beam arch-plate pressure film mechanism, the beam arch- plate compressive membrane mechanism, the beam catenary-plate tension membrane mechanism, and the plate tension membrane mechanism. The structural ultimate resistance occurs in the structure of extrapolated-admittance shift. Due to the strengthening effect of cast-in-place slabs on the upper part of beam, before the crushing of concrete in the compression area of the upper part of beam, the vertical reinforcement of the tensioned area of the lower part of beam has been greatly damaged. At this time, the vertical resistance of the structure appears to decrease significantly. The macroscopic deformation of the structure undergoes the horizontal extrapolation stage, the horizontal adduction stage and the collapse stage. The maximum lateral displacement of the structure does not exceed the lateral limit of the frame column in the specification of ＂code for seismic design of buildings＂ （GB 50011- 2010）, which indicates that the failure of single side column does not cause the continuous destruction of the adjacent column. The final structure collapse is controlled by the pull-off and the anchor of steel bars in the cast- in-place slabs. The unfavorable load is mainly redistributed through the beam connected with the failure column and the cast-in-place slabs. The beam without the association of the failure column appears significant tensional damage, which indicates that the plate tension membrane effect allows more components to be effectively involved in the destruction process of the structure collapse. After the failure of the frame beam, the cast-in-place slabs can provide 84. 9% resistance of the ultimate load, which reflects the improvement of cast-in-place slabs on the mechanical performance and deformation capacity of the overall structure. 10 figs, 22 refs.