后张法预应力空心板锚下应力分析与应变测试

后张法预应力空心板是桥梁工程中常见的上部结构形式。本文通过对后张法预应力混凝土空心板锚下应力进行理论分析,讨论加强钢筋的设置、腹板厚度对锚下应力的影响;测试钢束张拉力作用下空心板锚下应变,观察锚下混凝土裂缝情况,综合分析锚下裂缝产生机理。研究表明:提高锚下加强钢筋的配筋率和加厚腹板均可减小空心板锚下混凝土拉应力,加厚腹板效果更显著;锚下混凝土局部应力过大导致局部存在裂缝和结构损伤,预应力钢束张拉时裂缝不一定马上在混凝土表面出现,而是在锚下混凝土应力重分布后出现。

Stress analysis and strain test under anchor of post-tensioned prestressed hollow-core slab

Post-tensioned prestressed hollow core slab is a common form of superstructure in bridge engineering. In this paper, the theoretical analysis of anchor stress in post-tensioned prestressed concrete hollow core slabs was carried out, and the effects of setting of reinforcement bars and thickness of web on anchor stress were discussed; the strain under anchor of hollow core slabs under the tension of steel beam was tested, and the cracks under anchor concrete were observed to analyze the mechanism of cracks under anchor. The study showed that: increasing the reinforcement rate of under-anchor reinforcement and thickening the web can reduce the under-anchor concrete tensile stress, and the effect of thickening the web is more significant; excessive local stress in the under-anchor concrete leads to local cracks and structural damage, and the cracks do not necessarily appear on the concrete surface immediately when the prestressing beam is tensioned, but appear after the stress redistribution in the under-anchor concrete.