圬工拱桥加固与加载程序优化方法

Optimizing Method for Strengthening and Loading Program of Masonry Arch Bridge

为满足圬工拱桥施工阶段的结构安全并使其加固后处于更优的承载状态,提出采用平波法优化圬工拱桥的加固与加载程序。从圬工拱桥的极限承载力计算方法入手,推证拱圈截面承载力是截面合力偏心距e的单调减函数。在此基础上,以截面合力偏心距e及其容许值[e0]之差作为主要控制变量,引入并借助偏心距影响线的概念,通过调整加固、加载程序将阶线图中的波峰或波谷"烫平",使所有施工阶段中的e不超限且变化平稳、均匀。以重庆市某县乌江大桥(一座两孔净跨100m的圬工拱桥)加固程序优化为例,验证了平波法的有效性。

To ensure the structural safety of masonry arch bridge at the strengthening con- struction stages and to keep the bridge in a still better bearing state after it was strengthened, the smooth crest method was proposed for optimizing the strengthening and loading program of the bridge. Proceeding from the calculation methods for the ultimate bearing capacity of the bridge, the sectional bearing capacity of the arch rings was derived to be the monotonic decreasing func- tion of the eccentric distance e of the sectional resultant force. On the basis of the derivation, the differences between the eccentric distance e and its allowable value [e0] were taken as the main control variables, the conception of influential lines of the eccentric distance was introduced and by adjusting the strengthening and loading program, the wave peaks and wave valleys in the stage-varied line diagram were ＂flattened＂ and the e values of all construction stages were made not to exceed the limit and also made to change stably and uniformly. Finally, the optimizing of the strengthening and loading program of the Wujiang River Bridge （a two-span masonry arch bridge with net span length of 100 m） in a county in Chongqing City was cited as an example and the effectiveness of the smooth crest method was verified.