斜拉桥索塔锚固区预应力钢筋断裂及防护试验研究

为了确定预应力混凝土结构中的预应力钢筋意外断裂时的冲击效应,选取合适的防护措施,以某斜拉桥索塔锚固区构造为依托,采用有限元法计算预应力钢筋断裂时的冲击力,设计制作索塔锚固区模型,针对不同防护方案分别进行预应力钢筋破断冲击试验,研究其防护效果。结果表明:在正常工作状态下,预应力钢筋突然断裂时产生的冲击力较大,封锚混凝土无法承受,必须设置合适的防护构造措施;除未设置防护板的碳纤维布和玻璃纤维布的方案外,其余防护方案均能起到安全有效的防护作用;综合考虑工程应用要求,经过多方面比选确定,玻璃纤维板+玻璃纤维布组合为性价比最优的防护方案。

Experimental Study on Fracture and Protection of Prestressed Steel Bars in Anchorage Zone in Pylon of Cable-Stayed Bridge

In order to determine the impact effect of accidental fracture of prestressed steel bars in prestressed concrete structures, and to select appropriate protective measures, we adopted the finite element method to calculate the impact force when prestressed steel bars were broken on the basis of the anchorage zone structure in pylon of a cable-stayed bridge. Moreover, we designed and manufactured a model of anchorage zone in pylon and performed prestressed steel bar fracture impact tests for different protection schemes to study their protective effects. The results show that under normal working conditions, the impact force produced by sudden fracture of a prestressed steel bar is greater than the tolerant capacity of the anchored concrete, and thus suitable protective measures should be taken. Except for the scheme of carbon fiber cloth and glass fiber cloth without installing protective board, the other protective schemes can play an effective role in safe protective. To meet the requirements of engineering application, after many aspects of comparison and determination, the scheme of adopting the combination of glass fiber board and glass fiber cloth is optimum in cost performance.