冲击荷载作用下高强钢筋混凝土梁性能试验

为深入探讨冲击荷载作用下高强钢筋混凝土(RC)配筋梁的抗冲击性能,利用落锤试验机对6根简支RC梁进行了试验研究,分析了不同冲击锤质量和冲击能量下高强钢筋混凝土梁的抗冲击行为.采用高速摄像机记录了各试件在冲击过程中裂缝发生的过程,记录并分析了冲击力、支座反力和跨中位移时程曲线的特征.结果表明:冲击荷载作用下,剪切机理在结构整体反应中发挥重要作用,静态抗弯设计的梁也会出现明显的对称剪切裂缝,试件基体混凝土强度对整体反应影响不大,但能减小试件局部破坏程度;在已有数据与相关文献的基础上,建立了一个冲击荷载作用下试件最大跨中位移与试件本身抗弯承载能力之间的关系,用于验证两端简支的配筋RC梁(剪弯比1)的抗冲击性能;冲击荷载作用下,在外力传导至支座处之前的初始反应阶段,RC梁承受的冲击力基本被自身的惯性力所抵抗.结构自身的刚度和跨度是影响构件抗冲击能力的一个重要因素.

Experimental Study on the Behavior of High Strength Reinforced Concrete Beams Under Impact Load

To explore the shear-resistant behavior of RC beams under impact load, six simply-supported high strength RC beam with various shear reinforcement ratios, were tested under free-falling drop-weights, impacting the specimens at mid-span, and the effects of impact mass and impact energy on the shear resistant behavior of RC beams were investigated. The crack initiation, propagation and the failure patterns of the specimens were recorded using a high-speed video camera. The characteristics of time history of impact force, support pressure and mid-span displacement were described in details. The results obtained are as follows： Experimental studies reveal that shear mechanisms play an important role in the overall impact behavior of RC structures. Severe diagonal shear cracks occur even with statically flexural-critical RC beams tested under impact loads applied at the mid-span. Increase of concrete strength has less effect on the degree of overall failure, but it can reduce the specimen local failure near the impact loading point; This article summarizes the result of independent impact load experiment on the RC beam. It draws out the index that significantly influences between the maximum mid-span displacement and the static ultimate bending strength. It contributes to the impact resistance design method for simply-supported RC beam performance verification; During the initial stage before the external force reached the supports, the impact forces acting on the RC beam were mainly resisted by the inertia force of the specimens. The stiffness of a structure and the span length of a beam are important factors in resisting impact forces.