梁筋在节点中采用锚固板与90°弯折锚固的对比试验研究

为便于施工，明确高强梁筋在节点中采用锚固板锚固的可行性，对500MPa级高强梁筋分别采用锚固板锚固和传统90°弯折锚固的两组中间层端节点试件进行抗震性能对比试验。试验中，节点剪压比取为中等偏高及以上（0.238~0.367）；同时在柱中采用较高的轴压比（0.1~0.3）。试验结果表明：在中间层端节点中，高强梁筋采用锚固板锚固是可行的；在轴压比、剪压比（最大0.367）偏高，且节点的配箍特征值基本相同的前提下，高强梁筋采用这两种锚固方式节点的总体抗震性能大致相当，二者的延性和极限位移角基本相当，承载力退化速率基本相同；但加载后期由于节点混凝土的破损，与90°弯折锚固方式的节点相比，采用锚固板锚固的节点，其节点区剪切变形、梁上部钢筋的屈服向节点区发展更为显著，由此导致其梁上部钢筋的滑移量和屈服位移均略大。

Experimental research on beam-column joints with beam rebars anchored by heads or 90-degree hooks

The beam-column joint is subjected to a higher shear-compression ratio under the effect of the earthquake when utilizing high-strength reinforcement in the frame beam, resulting in the increased anchorage length of beam reinforcement in the joint. For the sake of the convenience of construction and clarifying the feasibility of utilizing heads to anchor high-strength beam reinforcement in the joint, experimental research on the comparison between seismic performances of headed bars and the conventional 90-degree hooked rebars of 500 MPa terminated in exterior beam-column joints were carried out. Medium to high shear-compression ratios (0.238~0.367) of the joint were utilized in the test. And the axial-load ratios (0.1~0.3) of column were set high. Major conclusions after analyzing the test results are as follows: In the exterior joint with high axial-load ratio and shear-compression ratio, utilizing heads to anchor high-strength beam bars is feasible; on the condition of high axial-load and shear-compression ratio and basically the same characteristic value of stirrup, the global seismic behaviors of high-strength reinforcement utilizing these two different types of anchorage are generally the same. The ductility, ultimate displacement angle and capacity degradation rate of them are generally the same. However, compared to the joints with 90-degree hooked bars, shear deformation and yielding penetration of the upper beam reinforcement of the joints with headed bars are more significant, which lead to slightly larger slip of the upper beam reinforcement and slightly larger yield displacement of beams, because of the damage of the concrete in the joints with headed bars.