外包不锈钢圆中空夹层钢管混凝土柱抗撞计算方法研究

CALCULATION METHOD FOR IMPACT RESISTANCE OF CIRCULAR CONCRETE-FILLED DOUBLE-SKIN TUBULAR COLUMNS WITH EXTERNAL STAINLESS STEEL TUBE

目前钢筋混凝土和实心钢管混凝土构件已广泛应用于实际工程,在抗冲击性能方面已形成相关设计方法,而针对外包不锈钢圆中空夹层钢管混凝土(CFDST)柱的耐撞性能研究较少。为此,该文在前期试验研究的基础上,采用ABAQUS建立了该类构件在轴力与侧向撞击耦合作用下的有限元模型。分析了轴力-撞击共同作用下该类构件的抗撞机理;重点研究了轴压比、名义含钢率等对构件抗撞性能的影响;给出了该类构件在轴力-撞击耦合作用下撞击力平台值动力放大系数(DIF)的计算公式。结果表明:外钢管的塑性变形是构件耐撞的主要耗能机制;轴压比对构件抗撞性能起削弱作用,且当轴压比大于0.5时,削弱程度更加明显;名义含钢率、外钢管与混凝土强度、撞击速度和截面外径对构件抗撞性能影响较大;建议的计算公式能够较好预测该类构件侧向撞击下的撞击力平台值。

Reinforced concrete and concrete-filled steel tubular members have been widely used in engineering structures and the design methods for the impact resistance have been suggested.However,studies on the impact resistance of circular concrete-filled double-skin tubular(CFDST)columns with external stainless steel tubes are limited.In light of this,the finite element analysis(FEA)model considering the coupling effect of axial and impact loads was established by ABAQUS based on preliminary experimental research.The impact mechanism under the combined action of axial and impact loads was investigated.The effects of axial load ratio,nominal steel ratio and other parameters on the impact resistance were studied.The formula used to predict the dynamic increase factor(DIF)of the plateau impact force subjected to axial and impact loads was suggested.The results show that the plastic deformation of outer steel tube is the main energy dissipation mechanism of members.Axial load ratio has a negative effect on the impact resistance of members,and the effect is significant when the axial load ratio exceeds 0.5.Nominal steel ratio,strengths of outer tube and concrete,impact velocity and cross-sectional diameter have significant effects on the impact resistance of members.The formula suggested in this study can reasonably predict the plateau impact force of members under lateral impact.