不同拼缝方向的预制带肋底板混凝土叠合板面内受力性能

In-plane mechanical property of superimposed concrete slab with precast ribbed panels jointed in different directions

对4个预制带肋底板混凝土叠合板试件和1个现浇混凝土板试件进行了面内低周反复加载试验,试件均呈正方形。4个叠合板试件分别为标准配筋、支座负筋加倍纵向拼缝叠合板,标准配筋、支座负筋加倍横向拼缝叠合板,现浇板试件作为对比。对各试件的破坏形态、滞回特性、变形性能、延性、刚度和耗能等进行对比分析。结果表明:预制带肋底板混凝土叠合板发生了剪切滑移破坏,现浇板发生剪切破坏。加载方向与预制带肋底板拼缝方向垂直的纵向拼缝试件的承载力、刚度均大于加载方向与拼缝方向平行的横向拼缝试件,延性也较好,耗能也较强。叠合板的刚度大于现浇板,现浇板延性略优于叠合板。增配支座负筋可使滞回环更加饱满,并可有效延缓开裂、改善延性、增加刚度、增强耗能。叠合板的预制底板一侧与现浇侧的裂缝发展及分布基本一致,二者协同工作性能良好。建议在实际工程中该叠合板宜适当提高穿孔钢筋和负筋的配筋率,以防止剪切滑移破坏。

4 superimposed concrete slabs and 1 cast-in-place slab,which were all built in the square shape,were tested under in-plane low-cycle repeated loading.The 4 superimposed concrete specimens were fabricated with normally reinforced and doubled negative moment reinforced longitudinal joints,and with normally reinforced and doubled negative moment reinforced transverse joints,respectively.The specimens were then evaluated for their performances according to the crack and failure mode,hysteretic characteristics,deformability,ductility,stiffness and energy dissipation capacity,respectively.The results show that the failure mode of the superimposed concrete slabs appears to be shear-slip,while that of the cast-in-place slabs appears to be shear.The superimposed slab with longitudinal joints loaded in the direction perpendicular to the joints has stronger bearing capacity and greater stiffness than the superimposed slab with longitudinal joints but loaded in the direction parallel to the joints,and in addition,the former also possesses a better ductility and energy dissipation capacity.Although the superimposed concrete slab has greater stiffness,its ductility is poorer than that of the cast-in-place slab.Increasing the negative moment reinforcement may improve the ductility,stiffness and the energy dissipation capacity of the superimposed slab,and moreover,it may lead to the more plum Physteretic curves.The precast slabs work concertedly with the cast-in-place concrete layer,and their crack patterns agree basically with each other.It is proposed that to prevent the shear-slip failure,more transverse reinforcement and negative moment reinforcement should be used in realistic applications.