长期持荷工况下钢管混凝土构件的抗撞击性能

为研究长期荷载作用对钢管混凝土构件抗撞击性能的影响，利用有限元软件ABAQUS建立了长期荷载与侧向撞击荷载作用的耦合分析模型以及撞击后剩余受压承载力计算模型。对比了一次加载模式下和长期荷载作用下构件遭受撞击的动力响应，采用剩余受压承载力系数量化分析了两种加载模式下构件的剩余受压承载力。典型的有限元模型分析表明:相较于一次加载模式，考虑长期荷载作用时撞击力峰值和平台值下降，撞击时间延长，构件跨中挠度增大，但撞击力对构件做功基本保持不变；考虑长期荷载作用的撞击过程轴向荷载做功比一次加载模式增大，增加的功主要通过外钢管的塑性变形耗散，核心混凝土贡献较小；长期荷载作用下构件的剩余受压承载力系数均低于一次加载模式，撞击条件相同时，一次加载模式下撞击后可以继续承载的构件在考虑长期荷载作用时可能会丧失承载能力；提高含钢率和钢材屈服强度、降低长期荷载比可有效减小长期荷载对构件抗撞击性能的不利影响。

Impact resistance of concrete-filled steel tubular members under long-term loading

In order to study the influence of long-term loading on the impact resistance of concrete-filled steel tubular (CFST) members, a finite element analysis (FEA) model was developed by using the software ABAQUS, which embeds the coupling analysis of long-term loading and lateral impact loading, along with the calculation of the residual compressive strength after impacting. The developed FEA models were verified by three tests. Based on the proposed method, the dynamic response of the CFST members under long-term loading was compared with that under primary loading. The residual compressive strength coefficient was used to quantitatively compare the residual compressive strength of the CFST members under those two loading modes and the influences of the steel ratio, steel yield strength, concrete strength, long-term loading ratio, slenderness ratio on the residual compressive strength coefficient were investigated as well. The results from the FEA show that compared with the primary loading mode, when considering the long-term loading, the peak and plateau values of the impact force decrease, the mid-span displacement increases, but the works done by the impact forces under two circumstances are equal. The work done by the axial load is more than that of the primary loading mode when the long-term loading is included, the excess work is mainly dissipated due to plastic deformation of the steel and the concrete has little contribution to the energy dissipation. At the same condition, the members that can continue to bear loads under the primary loading may lose their bearing capacity when considering the long-term loading. According to the parametric analysis, increasing the steel ratio and steel yield strength, and reducing the long-term loading ratio can effectively reduce the adverse effects of the long-term loading on the anti-impact performance of the members, with the increase of the slenderness ratio, the long-term loading will bring more adverse effects on the anti-impact performance of the members, the concrete strength has little effects on the impact resistance of the CFST members.