不同落锤速度冲击下混凝土和RC梁破坏研究

On failure behavior of concrete and RC beam to different velocity impact

为探究冲击载荷作用下钢筋混凝土(RC)梁的破坏模式转变及影响因素,对素混凝土梁和无箍筋轻RC梁试样开展落锤冲击实验及有限元分析,结果表明:(1)RC梁的冲击破坏模式与冲击速度、配筋率相关,在较低速度下以弯曲破坏为主,随速度提高将出现跨中呈现八字形的剪切破坏模式,并随纵筋率增大剪切破坏转变的临界速度呈增大趋势,但在更高速度下(>10 m·s-1),素混凝土及RC梁均会出现局部冲切破坏.(2)梁冲击力峰值随冲击速度增加而增大,受梁的配筋率影响较小,但在较高冲击速度下(>4.85 m·s-1),梁冲击力峰值并不随速度增加而增大;(3)有限元分析RC梁的冲击响应及破坏过程与实验现象及趋势符合较好.

To investigate the change in failure mode of the reinforced concrete(RC)beams and its influencing factors under dynamic load,both experimental test and finite element analysis are conducted to identify the effect of the loading rate and reinforcement ratio on the failure behavior of light RC beams under drop-weight impact.The results show that:1)the failure mode of RC beam is related to the longitudinal reinforcement ratio and loading rate,which varies from predominantly flexure to shear failure with the increasing impact velocity,and the punching shear is in the predominate failure pattern for beams under high speed impact(>10m·s-1in thispaper).Furthermore,the critical velocity of shear failure mode transformation increases with increasing longitudinal reinforcement ratio;2)For the light RC beam,the peak of impact force increases with increasing loading rates under slow-impact velocity,but it does not noticeably change when impact speed is high(>4.85m·s-1).Moreover,the reinforcement ratio of RC beam has less effect on the peak impact load;3)The variation tendency of the failure behavior and response of RC beam simulated by finite element model is in good agreement with the experimental results.