改扩建工程新旧桥拼接分析探讨

Study on Splicing Analysis of New and Old Bridges in Expansion Projects

结合佛开高速公路改扩建工程,针对预制空心板及T梁,对新旧桥拼接方案的选择及拼接计算思路进行探讨。最终选择上部结构连接、下部结构不连接的拼接方案,并采用Midas Civil建立新旧桥全桥梁格模型进行计算分析。重点对新旧桥龄期差产生的收缩徐变及新桥沉降进行了阐述。计算发现,这2方面的影响均非常显著,尤其对靠近拼接带的主梁更是如此。前者对新桥产生了全截面的拉应力,而对旧桥主要产生压应力;后者则对新旧桥均有不利影响。设计中应充分考虑这2个方面的影响。

Based on Foshan to Kaiping Highway expansion projects,mainly focused on hollow profile plates and T beams,the scheme comparison for splicing of new and old bridges and the analysis methods are elaborated in this paper.The splicing scheme was chosen finally,which the super-structure was connected while the sub-structure was separated,and the grillage model for the global analysis including the new and old bridges was built with Midas Civil.Two factors that have the greatest effects on the splicing analysis were elaborated in detail,i.e.the creep and shrinkage between the new and old bridges as well as the settlement of the new bridges.Based on the analysis results,both of the two factors have remarkable influence on the girders,especially for the girders near the splicing belt.The former caused tensile stress on the new girders and compression stress on the old girders while the latter caused both tensile and compression stress on all the girders.So these two factors must be taken into account for a proper design.