预应力混凝土连续梁翼缘后浇影响研究

Study on Influence of Flange Post-pouring on Prestressed Concrete Continuous Beams

摘要:

在部分特殊情况下，由于施工条件受限，箱梁的翼缘需要部分后浇。国内目前已有的箱梁翼缘后浇案例均为预制简支箱梁，在连续梁中还没有相关案例。与简支梁不同，连续梁由于存在负弯矩，其结构受力更为复杂。以某主跨64 m预应力混凝土连续梁桥为例，提出了2种翼缘后浇方案，并采用MIDAS Civil和MIDAS Fea模拟箱梁翼缘后浇对预应力混凝土连续梁的影响。结果表明：箱梁由于悬浇施工时翼缘缺失、截面惯矩减小，对预应力荷载变得更为敏感，在标准组合下压应力容易超规范限值；先减小悬浇阶段钢束荷载，翼缘浇筑后再增设钢束，且后浇翼缘材料采用高抗拉、低收缩材料的方案可以满足规范要求。

Abstract:

Under some special circumstances, the partial post-pouring of box girder flanges is required due to restrictions of construction conditions. Currently, all the existing cases of post-pouring box girder flanges in China are prefabricated simple-supported box girders. There are no relevant cases in continuous girder bridge. Unlike simple-supported girder bridges, the structural forces of continuous beams are more complex due to the existence of negative bending moments. Taking a prestressed concrete continuous beam bridge with a main span of 64 m as an example, two kinds of flange post-pouring schemes are proposed. MIDAS Civil and MIDAS Fea are used to simulate the influence of box girder flange post-pouring on prestressed concrete continuous beams. The results show that due to the absence of flanges and the reduction of the inertial moment of the section during the suspension pouring construction, the box girder becomes more sensitive to prestressed loads. Under the standard combination, the compressive stress is easy to exceed the limit specified in the code. The scheme of first reducing the steel bundle load during the suspension pouring stage, then adding the steel bundle after the flange pouring, and using high tensile strength and low shrinkage materials for the post-poured flange can meet the specification requirements