基于高性能材料的大跨径斜拉桥抗风性能分析

为了研究活性粉末混凝土(Reactive Powder Concrete,RPC)和碳纤维复合材料(Carbon Fiber Reinforced Polymer,CFRP)在大跨径斜拉桥中应用的可行性,以主跨1 100m的钢斜拉索、钢主梁、普通混凝土索塔斜拉桥设计方案为基础,构造了一座同等布置形式的CFRP拉索、RPC主梁、RPC索塔斜拉桥方案.采用有限元法对2种方案斜拉桥的动力特性、抗风性能等进行了分析和比较.结果表明:2种方案结构的自振基频相差不大,CFRP索RPC主梁斜拉桥的主梁颤振稳定性有所提高,其抖振响应位移较钢索钢主梁斜拉桥明显降低.CFRP拉索的自振频率达钢斜拉索的2倍;与钢斜拉索相比,CFRP拉索涡振幅值有所增大,但整体而言2种方案斜拉索的涡振幅值均很小,不影响其安全;CFRP拉索的风雨激振振幅不到钢斜拉索的1/2,且前者与风雨激振相关的临界风速较后者有所提高.应用高性能材料RPC与CFRP的大跨径斜拉桥整体抗风性能优于传统的钢斜拉索钢主梁斜拉桥,从抗风性能角度而言,将高性能材料RPC与CFRP应用于大跨径斜拉桥中是可行的.

Wind-resistance Performance Analysis of Long Span Cable Stayed Bridge Using High Performance Materials

In order to investigate the applicability of reactive powder concrete (RPC) and carbon fiber reinforced polymer (CFRP) in long span cable-stayed bridges, two cable-stayed bridges with the same span-length, 1100m, are designed for comparison. One is composed of steel stay cables, steel main girder, and ordinary concrete tower, while the other is composed of CFRP cable, RPC main girder and RPC tower. Dynamic properties and wind-resistant performances of the two schemes are analyzed and compared by using the finite element method. The results show that the two schemes show insignificant differences in fundamental natural frequencies, but the flutter stabilities for the RPC girder of the bridge with CFRP cable, RPC main girder and RPC tower is improved. The buffeting response displacement can be much reduced when the RPC girder and CFRP stay cables are employed. Natural frequencies of CFRP cables reach as high as 2 times of those of the steel cables. Compared with the steel cable, the vortex-induced vibrating amplitude of CFRP cables increases. However, the amplitudes of both schemes are very small, and hence they could have no effects on the structural safety. Rain-wind vibration amplitudes of CFRP cables can be as low as half of those of the steel cables. Moreover, critical wind speeds of the former are higher than the latter. In general, as far as the wind-resistant performance is concerned, RPC and CFRP can have an advantage over the traditional 3409 steel material in applications to long span cable-stayed bridges. In view of this point, it is feasible to apply high-performance materials, RPC and CFRP, to long span cable-stayed bridges.