配置大间距HRB500高强纵筋的混凝土叠合梁受弯性能试验研究

对8个采用大间距、大直径HRB500纵筋的钢筋混凝土叠合梁和2个对比试件进行了静力试验,研究了纵筋间距、箍筋肢距和构造钢筋对叠合梁受弯性能的影响。结果表明:在截面配置大间距■40或■32受力纵筋的混凝土叠合梁,其裂缝分布形式和裂缝发展与普通配筋叠合梁相近,但开裂早于普通配筋叠合梁,开裂荷载小于GB 50010—2010《混凝土结构设计规范》的计算值;受力性能与普通配筋叠合梁相近;受弯承载力及短期刚度可以按照GB 50010—2010计算。增加纵向构造钢筋对裂缝开展、屈服荷载和受弯承载力的影响较小。试件受弯主裂缝的位置大多位于箍筋处,平均裂缝间距与规范计算值差异较大。按照JGJ 1—2014《装配式混凝土结构技术规程》规定的叠合面要求制作的试件,在峰值荷载前,未出现叠合面破坏。

Experimental study on flexural performance of RC composite beams with large spacing HRB500 high-strength longitudinal rebars

Static loading tests on eight RC composite beams with large spacing and large diameter HRB500 reinforcement and two ordinary RC composite beams for comparison were conducted to investigate the influence of longitudinal reinforcement spacing, stirrup leg spacing and longitudinal detailing rebar on the flexural performance. The test results show that, the RC composite beams with 40 or 32 longitudinal rebars at the four corners of the sections have similar crack distribution pattern and propagation process with the ordinary RC composite beams, but start to crack earlier than the latter; the cracking loads are lower than the values calculated by using Chinese code GB 50010—2010 ‘Code for design of concrete structures’; the two are similar in the overall performance; the flexural capacities and short time stiffness of the eight beams can be calculated according to GB 50010—2010. The additional longitudinal detailing rebars have little effect on the crack propagation process, yield loads and flexural capacities of the beams. The main flexural cracks of the specimens are mostly located at the positions of stirrup legs, resulting in differences between the tested average crack spacing values and the calculated values. Before the peak loads, the interface of the cast-in-situ and precast concrete fabricated according to the requirement of Chinese standard ‘Technical specification for precast concrete structures’ is not damaged.