双向荷载作用下空间夹心节点受力性能试验研究

节点核心区采用同梁等强的低强度混凝土浇筑的夹心节点和采用同柱等强的高强度混凝土浇筑的传统节点相比,施工简单且易保证质量,但是我国规范对其规定过于简单,没有明确的验算方法。通过三组不同混凝土强度等级差的空间夹心节点和传统节点对比试件的双向低周往复性能试验研究,对比分析了二者破坏形式、延性、耗能、变形和承载力等方面的差异,结果表明:中低剪压比夹心节点的整体抗震性能稍弱于传统节点,但相差不明显;中低轴压比、剪压比条件下,当柱与梁混凝土强度等级之比小于1.5时,节点区可直接采用与梁相同强度等级的混凝土浇筑,当柱与梁混凝土强度等级之比大于1.5时,其破坏形式可转变为节点核心区剪切破坏,需采取相应的加强措施。最后在此基础上,给出了与试验结果吻合较好的夹心节点抗剪承载力计算公式。

Experimental study on the mechanical behavior of 3D sandwich joints under bi-directional loading

The core area of "equal beam equal strength" sandwich beam-column joints has the advantage of easy construction and quality control, compared with the core area of traditional"equal column equal strength joints;however, there have been no explicit calculation methods but only simple provisions in current Chinese design codes regarding the weak-strength joint. In this paper, three groups of sandwich joint specimens with different concrete strength were tested under bi-directional reversed cyclic loads, and their seismic performance was investigated, including the failure mode, ductility, energy dissipation, deformation and carrying capacity. The test results show that with low-to-moderate axial compression ratio, the seismic performance of sandwich joints is slightly weaker than that of traditional joints with insignificant difference. For the case where the ratio of the column concrete compressive strength to the beam concrete compressive strength is less than 1.5, the joint concrete can be of the same strength as the beam;otherwise, the failure mode may change from flexural failure of the beams to shear failure of the joint, and thus some strengthening measures are needed. Finally, a new formula is presented for calculating the shear capacity of the sandwich joints, which is consistent with the experimental results.