摘要:
圆端形钢管混凝土构件在桥梁墩柱、主塔等应用中，可能面临船舶、车辆、漂浮物等撞击作用。为此，本文聚焦压弯和撞击耦合作用后圆端形钢管混凝土柱的剩余力学性能，开展了撞后剩余力学性能试验，获得了不同偏心率和轴压比影响下试件的破坏模式、荷载-跨中位移与荷载-纵向应变曲线。此外，基于ABAQUS软件建立了144个圆端形钢管混凝土柱侧向撞击与剩余承载力分析模型，重点分析了撞击速度、偏心率、轴压比、长宽比和含钢率对撞后残余挠度与剩余承载力的影响规律。最后，基于响应面分析法提出了多因素交互影响下该类试件的撞后残余变形与剩余承载力系数预测公式。结果表明：圆端形钢管混凝土压弯柱在侧向撞击下以整体变形为主；偏心受压过程中荷载-柱中侧向位移曲线呈现较为平缓的下降段，表明试件延性良好；随着轴压比与偏心率的增大，试件剩余承载力降低。通过考虑多因素交互影响建立的响应面模型能较好地预测圆端形钢管混凝土柱撞后残余变形与剩余承载力系数。
Abstract:
Round-ended concrete-filled steel tube (RE-CFST) members, commonly used in bridge piers and main towers, are often subjected to impacts from vessels, vehicles, floating debris, and other potential collisions. Therefore, this paper focuses on the residual mechanical performance of RE-CFST columns exposed to the combined effect of eccentric compression and impact loading. The post-impact compression tests were conducted, and the failure modes, load-midspan displacement, and load-longitudinal strain curves under different eccentricity ratios and axial-load ratios were obtained. The results showed that the RE-CFST beam-columns primarily presented global deformation under lateral impact. Under eccentric compression, pronounced local buckling was observed in the outer steel tube on the compression side. The load-lateral displacement curve of the column under eccentric compression showed a gentle decrease, indicating good ductility of the specimen. As the eccentricity ratio and axial-load ratio increased, the residual resistance of the specimen decreased. In addition, based on ABAQUS software, a total of 144 finite element (FE) models were established to analyze the lateral impact behavior and residual resistance of RE-CFST columns. The effects of impact velocity, eccentricity ratio, axial-load ratio, aspect ratio, and steel ratio were emphatically studied. Results indicate that with the increase in steel ratio and aspect ratio, the post-impact residual deflection of the specimens decreases, while the residual bearing capacity improves. Finally, based on response surface analysis, formulas for the residual deformation after an impact and residual resistance coefficients of these specimens under the interaction of multiple factors were proposed. The results show that the aspect ratio is a key factor affecting both post-impact residual deflection and residual bearing capacity coefficients. Furthermore, the interaction between aspect ratio and eccentricity ratio, as well as between aspect ratio and impact velocity are significant. The proposed formulas can well predict the post-impact residual deformation and residual bearing capacity coefficients of RE-CFST columns.
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