多次冲击下RC梁损伤特征及剩余承载性能研究  

Damage Characteristics and Residual Load-bearing Performances of RC Beams Under Multiple Impacts

作　　者：张景峰 李晨涛 李铮 杜威 吴俊霖 张先文 ZHANG Jing-feng;LI Chen-tao;LI Zheng;DU Wei;WU Jun-lin;ZHANG Xian-wen(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;Chongqing Urban Construction Investment(Group)Co.Ltd.,Chongqing 400023,China)

机构地区：[1]长安大学公路学院,陕西西安710064 [2]重庆市城市建设投资(集团)有限公司,重庆400023

出　　处：《中国公路学报》2024年第5期201-210,共10页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(52378477);中央高校基本科研业务费专项资金项目(CHD300102212911);重庆市杰出青年科学基金项目(CSTB2022NSCQ-JQX0020)。

摘　　要：极端条件下工程结构会受到反复冲击荷载作用,深入理解多次冲击作用后RC梁的承载性能演化规律对于工程结构安全服役至关重要。对5片RC梁进行了单次、多次落锤冲击和四点弯曲静载试验,研究了冲击次数、冲击次序和冲击能量对RC梁冲击动力响应和累积损伤特征的影响,基于剩余承载力、剩余刚度、剩余延性和塑性变形能等指标讨论了不同冲击加载方案下损伤RC梁的剩余性能演化规律。研究结果表明:在累积冲击能量相等的情况下,单次大能量冲击比多次小能量冲击造成的RC梁冲击区域局部损伤更严重,其剩余承载性能下降幅度更大,冲击塑性损伤耗能占比更高;累积能量相等但是首先进行大能量冲击的情况下,RC梁的承载性能劣化更为严重,后续静载耗能能力显著降低;累积冲击能量的增加会使构件的损伤程度和剩余承载性能劣化程度加剧,当构件的累积冲击位移接近或者超过构件静载极限状态的竖向位移时,RC梁性能退化显著,已不适于继续加载。Engineering structures are often subjected to repeated impact loadings under extreme conditions.Understanding the evolution of the load-bearing performances of reinforced concrete(RC)beams after multiple impacts is critical for the safe operation of engineering structures.In this study,five RC beams were subjected to single and multiple drop-hammer impacts and quasistatic loading.The effects of the number of impacts,impact sequence,and total impact energy levels on the dynamic response and cumulative damage characteristics of the RC beams under impact were studied.The evolution of the residual performances of damaged beams under different impact loading methods was discussed based on the indices of residual resistance,residual stiffness,residual ductility,and plastic deformation energy.The results indicate that with equal cumulative impact energy,a single high-energy impact inflicts more severe local damage on an RC beam than multiple low-energy impacts.The reduction in the residual load-bearing resistance is more pronounced,and the proportion of energy attributed to impact-induced plastic damage is higher.With equal cumulative energy but a high-energy impact occurring first,the deterioration in the load-bearing performances of the RC beam is more severe,and the subsequent static loading energy absorption capacity is significantly reduced.An increase in the cumulative impact energy increases the extent of damage and further deteriorates the load-bearing performances of the components.If the cumulative impact displacement of a component approaches or surpasses the vertical displacement in the limit state of static loading,the performances of the RC beams degrade significantly,indicating that they cannot be subjected to further loading.

关 键 词：桥梁工程 钢筋混凝土梁 落锤试验 多次冲击作用 剩余承载能力 塑性耗能 

分 类 号：U443.2[建筑科学—桥梁与隧道工程]