高强圆钢管混凝土短柱轴压承载力试验研究

为了研究高强钢管混凝土短柱的承载性能，进行了13个高强圆钢管混凝土短柱轴压试验，从破坏模式、荷载-位移关系、承载力、残余承载力和延性方面对内填普通强度混凝土和超高性能混凝土的短柱受力性能进行了对比分析，研究了钢管强度、混凝土强度以及径厚比对两种钢管混凝土短柱的轴压性能影响。试验结果表明：钢管混凝土短柱的破坏模式与等效径厚比相关，分为腰鼓型破坏和剪切型破坏两种；在相同钢管强度及径厚比条件下，内填普通强度混凝土的短柱较内填高性能混凝土的短柱具有更高的承载力提高系数和残余承载力比，以及更好的延性。同时，将试验承载力结果与我国GB 50936—2014《钢管混凝土结构技术规范》、欧洲规范BS EN 1994-1-1：2004和美国规范ANSI/AISC 360-16中相关公式计算结果进行对比，发现现行规范一定程度上高估了高强钢管超高性能混凝土短柱的承载力。结合已有试验统计数据与高强圆钢管混凝土短柱试验结果，对圆钢管高强及超高强混凝土短柱受压截面承载力计算公式进行修正，得到偏安全的短柱轴压承载力计算公式。

Experimental study on behavior of circular concrete-filled high- strength steel tubular stub columns under compression

To investigate the mechanical behavior of concrete filled high-strength steel tube (CFHST) stub columns, the tests on 13 CFHST stub columns under axial load were carried out. Analysis and comparisons were performed between circular high-strength steel tube filled with normal strength concrete and ultra-high-performance concrete (UHPC), in terms of failure mode, load-displacement curve, bearing capacity, residual bearing capacity and ductility, mutually and respectively. And the effects of the yield strength of steel, the compressive strength of concrete and diameter-to-thickness ratio of the steel tube on the axial compressive performance of the two kinds of CFST stub columns were explored. The test results show that the failure modes of CFST stub columns are related to the equivalent diameter-to-thickness ratio, which can be divided into two types, waist drum-shaped failure and shear failure. For steel tubes with the same strength and diameter-to-thickness ratio, the stub column filled with normal strength concrete shows higher resistance enhancement index, residual bearing capacity ratio and ductility index than those of the stub column filled with UHPC. The tested bearing capacity results were compared with the theoretical results calculated according to Chinese code GB 50936—2014, European code EC4, and American code AISC 360-16. And the results show that current codes overestimate the bearing capacity of the ultra-high-performance concrete-filled high-strength steel tube stub columns to a certain extent. Based on existing test statistics and the test results in this study, the design formulas of axial compressive bearing capacity of CFST stub columns infilled with high-strength and ultra-high-strength concrete were modified to obtain conservative calculation results.