组合L形冷弯钢管混凝土柱抗震性能试验研究

Experimental Study on the Seismic Performance of L-shaped Cold-Formed Concrete-Filled Steel Tubular Composite Columns

以荷载作用方向、截面类型、肢高宽比为参数,进行了4根组合L形冷弯钢管混凝土柱的拟静力试验,分析了各参数对试件破坏形态、承载力、延性及耗能等抗震指标的影响。并应用ABAQUS有限元软件建立了数值分析模型,分析了钢管厚度、轴压比等参数对试件承载力和延性影响。结果表明:试件的主要破坏模式为钢管鼓曲开裂,异形钢管的制作方式对试件破坏形态有一定影响,冷弯钢管组合焊接的试件未出现角部开裂,钢板组合焊接的试件出现角部纵向焊缝开裂现象,加快了试件的变形发展;荷载作用方向对试件延性和耗能能力影响不大,但对试件承载力有较大影响,工程设计中除主要工程轴向的承载力验算外,同时也应考虑最不利加载方向的承载力验算;增大肢高宽比可以有效提高试件承载力,但会加剧试件正、负向受力性能的差异、削弱其延性和耗能能力,可以改变截面形式调整其正、负向承载力差异、增加钢管厚度改善其延性;轴压比对试件正向承载力和延性影响较大,随着轴压比的增加,试件正向承载力和延性明显下降。

The pseudo-static tests of four L-shaped cold-formed CFST composite special-shaped columns were conducted with load direction, section type, and limb length-to-width ratio as parameters, and the effects of each parameter on failure mode, bearing capacity, ductility and other seismic indexes were analyzed. The ABAQUS model for numerical analysis was developed, and the effects of steel tube thickness, axial pressure comparison, and other parameters on the specimens’ bearing capacity and ductility were examined. The results indicate that the primary failure mode of the specimens is steel tube buckling and cracking;the manufacturing method of special-shaped steel tube affects the failure mode of the specimen;the crack of the corner weld appeared in SJ3, which accelerates the development of specimen deformation;and the direction of the load has little effect on the ductility and energy dissipation capacity of the specimen, but has a significant effect on the bearing capacity of the specimen. In engineering design, the bearing capacities in main axes should be considered in addition to assessing the bearing capacity of the most unfavorable loading direction. Increasing limb length-to-width ratio can increase the bearing capacity of specimens but exacerbates the difference between positive and negative mechanical properties, thereby reducing their ductility and energy dissipation capacity. Changing the cross-sectional form can adjust the difference between its positive and negative bearing capacity, and increasing the thickness of the steel pipe can improve its ductility.The axial compression ratio had a great influence on the positive bearing capacity and ductility of specimens. With the increase of the axial compression ratio, the positive bearing capacity and ductility of specimens decreased obviously.