热轧H型钢组合柱轴压承载性能研究

Bearing capacity of hot-rolled H-section steel composite columns under axial compression

热轧H型钢组合柱是由热轧H型钢与钢板焊接拼合而成,并在内部灌注混凝土形成钢-混凝土组合截面构件。为研究热轧H型钢组合柱的轴压承载性能,完成了3个热扎H型钢组合短柱轴压试验,得到了试件在轴压荷载下的破坏形态、荷载-位移关系曲线和荷载-应变关系曲线等。建立了经试验验证的精细化有限元模型,并以钢材强度、混凝土强度和长细比为关键参数进行分析。研究结果表明:热轧H型钢组合柱的延性很好,但是试件端部H型钢外伸翼缘由于约束较弱,所以轴压荷载作用下先行屈曲;试件截面中部腹板拼接焊缝处钢板的宽厚比较大,易出现局部稳定问题;采用的有限元模型可准确模拟试件在轴压荷载下的破坏形态、荷载-位移关系等。在混凝土强度等级C20~C90、钢材强度等级Q235~Q420范围内,基于试验和有限元分析结果,提出钢-混凝土组合构件的轴压短柱承载力和中长柱的稳定承载力计算公式,公式计算结果与试验值及有限元分析值吻合较好。

Hot-rolled H-section steel composite column is a kind of steel-concrete composite section member composed of hot-rolled H-section steel and steel plate welded together. In order to investigate the bearing capacity of the composite columns under axial compression, three hot-rolled H-section steel composite short columns were designed and tested under axial compression. The failure modes, load-displacement curves and load-strain curves of the specimens under axial compression were analyzed. A refined finite element(FE) model was established and validated, and the parametric analysis were carried out to investigate the three key parameters including the steel strength, concrete strength and the ratio of length to thickness. The results show that the ductility of hot-rolled H-section steel composite columns is very good, but the outward flanges were subjected to weak constraint and local buckling occurs first in it. And the welds of the H-section flanges with large width to thickness ratio in the middle section of the specimen,which is prone to local stability problems. And the FE model can accurately simulate the failure mode and load-displacement curve of specimens under axial compression. The concrete strength grades were considered from C20 to C90 and the steel strength grades were considered from Q235 to Q420, based on the experimental and FE analysis results, the design methods for calculating the bearing capacity of short columns and stability bearing capacity of the medium and long columns under axial compression are proposed, and the predicted results of the design method are in good agreement with the experimental and FE analysis results.