基于有限元法的T形刚构桥施工过程中主梁状态分析

Analysis of Main Beam State During Construction of T-shaped Rigid Frame Bridge Based on the Finite Element Method

悬臂浇筑法是目前大跨度梁桥的主要施工方法,在悬浇法施工中主梁的挠度和应力随施工的进行不断变化,随着主梁悬臂长度的增加,悬臂根部处主梁的应力、悬臂端侧主梁的挠度均不断增加。为有效评估悬浇施工过程中的结构状态确保结构安全,以广州市东部固体资源再生中心环一路高架桥主桥2×70 m跨的预应力混凝土T形刚构桥为工程背景,采用midas Civil软件建立其有限元模型,计算分析了桥梁从墩身施工到成桥各施工阶段的应力及位移,结果表明:(1)长悬臂阶段随着悬臂长度的增加,悬臂端下挠值急剧增长,施加节段预应力能够有效抵消混凝土自重对挠度的影响,现场施工时应采取措施尽量减小预应力损失;(2)施工过程中主梁顶、底板应力均在规定限值范围内,悬浇施工过程中结构安全,成桥状态下主梁全截面受压且具有较大的应力储备。

Cantilever casting method is the main construction method of large-span beam bridge at present.In the construction of cantilever casting method,the deflection and stress of the main beam constantly change with the construction.With the increase of the cantilever length,the stress of the main beam at the root of the cantilever and the deflection of the main beam at the end of the cantilever are constantly increasing.In order to effectively evaluate the state of the structure in the process of suspension pouring construction to ensure the safety of the structure,with a 2×70 m span prestressed concrete T-shaped rigid frame bridge as the engineering background,using midas Civil software to establish its finite element model,calculate and analyze the bridge from pier construction to the construction stage of the bridge stress and displacement,the results show that:(1)In the long cantilever stage,with the increase of the cantilever length,the cantilever end deflection value increases sharply.The application of segmental prestress can effectively offset the influence of concrete dead weight on the deflection,and measures should be taken to minimize the prestress loss during field construction.(2)The stress of the top and bottom of the main beam in the construction process is within the standard limit range.The structure is safe in the process of suspension pouring.Under the condition of bridge,the whole section of the main beam is compressed and has a large stress reserve.