高温与冲击耦合作用下双钢管混凝土柱动态响应数值模拟研究

Numerical simulation study on dynamic response of concrete-filled double-tube columns under coupled high temperature and impact

为研究双钢管混凝土(concrete-filled double-tube,CFDT)柱在高温下的抗冲击性能,利用ABAQUS有限元软件建立CFDT柱在高温与冲击耦合作用下的有限元模型,考虑材料的温度软化、应变率强化效应以及轴力的影响,并通过已有CFDT柱的火灾试验和常温下侧向冲击试验进行了分段验证。在此基础上,从冲击力、跨中位移、荷载分布情况与损伤演化等方面分析了不同温度下CFDT柱的抗冲击动态响应,并考虑了不同截面形式、轴压比、冲击速度和混凝土强度对CFDT柱抗冲击性能的影响。研究结果表明,在高温与冲击耦合作用下,CFDT柱主要呈现弯曲破坏,随着温度升高,CFDT柱抗冲击性能和抗弯承载力逐渐降低。CFDT柱的耐火极限是普通钢管混凝土柱的2.1倍。轴力对CFDT柱抗冲击性能产生不利影响,当轴压比从0增加到0.6,高温800℃时构件冲击力平台值下降了32.4%;混凝土强度对高温下CFDT柱抗冲击性能有显著影响,高温800℃时混凝土强度由40 MPa增加到60 MPa,构件冲击力平台值提高了22.8%。

To study the impact resistance of concrete-filled double-tube(CFDT) columns at high temperature,a 3D finite element numerical model of CFDT columns under coupled high temperature and impact was established via ABAQUS,considering material softening temperature,strain rate of reinforcement effect and the influence of axial force.The results were verified by existing fire tests and lateral impact tests of CFDT columns at room temperature.On this basis,the dynamic response of CFDT columns at different temperatures was analyzed from the aspects of impact force,mid-span displacement,load distribution and damage evolution.Then,the effects of different section forms,axial compression ratio,impact velocity and concrete strength on the impact resistance of CFDT columns were considered.The results show that CFDT columns mainly exhibit bending failure under coupled high temperature and impact.With the increase of temperature,the impact resistance and flexural capacity of CFDT columns gradually decrease.The fire resistance of CFDT columns is 2.1 times as much as that of normal concrete-filled steel tube columns.The axial force has a negative effect on the impact resistance of CFDT columns.When the axial compression ratio increases from 0 to 0.6,the platform value of impact force decreases by 32.4% at 800 ℃.The concrete strength has significant influence on the impact resistance of CFDT columns at high temperature.When the concrete strength increases from 40 MPa to 60 MPa,the platform value of impact force increases by 22.8% at 800 ℃.