适筋空心板开裂后弹性阶段受力裂缝影响

Influence of Stressed Crack in the Elastic Phase After Cracking Analysis on Balanced-reinforced Hollow Slab

为探索适筋空心板开裂后弹性阶段的受力裂缝对结构静动力特性的影响,设计了单板加载试验并结合非线性有限元分析对经历开裂后弹性阶段的20 m适筋空心板卸载后的受力特性进行研究.单板加载试验通过现场配重块分级加载进行,有限元分析采用可进行开裂模拟的Midas FEA非线性静力分析进行.试验分析结果表明:超重车辆对空心板桥产生的损伤在作用荷载小于设计荷载时即可体现,表现为刚度降低,挠度、应变增大;存在开裂后弹性阶段受力裂缝的空心板桥在不作用更大的荷载之前,与挠度相关的结构整体刚度不会发生明显变化,作用荷载小于设计荷载时,仍能满足设计要求,再次承受超过设计荷载的作用时,安全储备降低;开裂后弹性阶段的结构损伤可反映至结构动力特性,但其敏感程度低于静力特性.

To explore the influence of stressed crack of cracked balanced-reinforced hollow slab in elastic phase on structural static and dynamic characteristics, the mechanical characteristics of a 20-metre balanced-reinforced hollow slab were researched by a load test and nonlinear finite element analysis. The load test was carried out by multi-stage loading and the finite element analysis was performed by Midas FEA nonlinear static analysis. Results show that the damage of overweight vehicle has ocuured before the applied load meets the designed load, which can be observed by the decreasing stiffness, and increasing deflection and strain. The structrual stiffness of cracked hollow slab in elastic phase does not vary obviously without a higher applied load, and the slab can meet the design requirements with an applied load lower than the design load, whereas has a lower safety stock with the applied load higher than the design load. The dynamic characteristic reflects structural damage with a lower sensitivity level compared to static characteristic.