组合封闭箍筋混凝土梁受扭性能试验研究

Experimental study on torsion behaviors of RC beams with two-piece enclosed stirrups

采用自行研发的受扭试验装置,研究采用组合封闭箍筋且两次浇筑的混凝土叠合梁受扭性能。对比试验分2批,第一批试验包括12根梁试件,研究参数考虑箍筋形式和配筋率。第二批试验包括8根梁试件,参数选取浇筑方式和配筋率。研究表明,相比采用传统箍筋的梁,采用组合封闭箍筋的梁受扭极限承载力降低幅度约3.7%。叠合界面的存在对梁受扭也有不利影响。第二次浇筑的强度较高的混凝土有助于提高梁受扭极限承载力,研究显示提高幅度约6.7%。可以近似认为组合封闭箍筋叠合梁与传统箍筋整浇梁具有相同的受扭性能,前者受扭极限承载力设计值仍采用我国规范推荐的方法计算。

Torsion behaviors of reinforced concrete beams with two-piece enclosed stirrups and cast in tow times were investigated using a self-developed torsion test device. The test program was divided into two groups. The first group included twelve beam specimens considering different stirrup forms and reinforcement ratios. The second group included eight beam specimens considering different casting forms and reinforcement ratios. The results indicates that torsion ultimate bearing capacities of beams reinforced with two-piece enclosed stirrups decreased by about 3. 7% compared to those reinforced with traditional stirrups. The torsion performance was also detrimentally affected by the presence of concrete to concrete interface. The second-cast concrete with higher strength helps to increase the torsional ultimate bearing capacity of the beam about 6. 7%. It can be approximated that the beams with two-piece enclosed stirrups have the same torsion performance as the reinforcement beams with conventional stirrups. The design value of the torsional ultimate bearing capacity of the beams with two-piece enclosed stirrups can still be calculated by the method recommended by China＇ s specifications.