中文摘要：

以衡阳耒河的预选合龙方案为依据，通过MIDAS有限元软件模拟该桥4种不同方案的施工过程，从最终合龙后在短期组合作用下跨中底板应力分布情况以及承栽能力组合状态下每跨的最大累计位移2方面对合龙方案进行对比分析，并得到最合理的合龙顺序。研究结果表明：混凝土的收缩徐变变形与混凝土加栽龄期有关，混凝土徐变随加栽龄期的增长而单调的衰减，考虑不同的混凝土初始龄期通过MIDAS有限元软件模拟在成桥，成桥3a；成桥10a后桥梁跨中最大挠度，确定合理的初始加载龄期，节省施工时间的同时对后期挠度的影响不大。

英文摘要：

Based on the preselected closure scheme of River Lei in Hengyang City of Hunan Province, through four different construction processes of closure schemes of the bridge simulated by MIDAS finite element soft ware, a preliminary analysis was conducted on the closure scheme from two aspects ： One is the stress distribution of mid span bottom plate under short term combined loads after the final closure and the other is the maximum cumulative displacement of each span under the condition of the assembly of bearing capacity, and the most rea sonable closure sequence was obtained. The result shows that the shrinkage and creep deformation of concrete are associated with the loading age. Concrete creep decays monotonously with the increase of loading age. Different ages of the concrete were considered with the MIDAS finite element software which have was used to simu late the biggest deflection of the bridge at three time points, including the time when the bridge is finished, three years after the completion of the bridge and 10 years after the completion of the bridge, and the reasonable initial loading age was determined so as to save construction time and meanwhile it has little impact on the later deflection.