南京绕越高速玉春桥钢腹板箱梁现场试验研究

Field Test of Box Beams with Corrugated Steel Webs in Yuchun Bridge of Freeway Around Nanjing

江苏省南京绕城高速公路玉春车行天桥采用波纹钢腹板预应力混凝土箱梁,目前针对该新型箱梁结构形式的研究多采用缩尺模型和有限元分析,缺乏工程现场试验数据.本文结合玉春桥结构特点,制定可用于现场拟静载试验的试验方法和测试技术,通过现场监测获得了波纹钢腹板箱梁变形、正应变试验数据,进而分析了波纹钢腹板梁的抗弯、抗剪、抗扭性能.分析结果表明,现场试验结果规律与理论规律基本吻合;波纹钢腹板箱梁混凝土顶、底板正应变符合"拟平截面假定",且钢腹板上的应变较小;箱梁存在较明显的正剪力滞效应;在偏心荷载作用下,波纹钢腹板箱梁存在约束扭转,产生附加正应力,箱梁两侧钢腹板倾角有所不同;箱梁截面实际中性轴受防撞墙及周围结构的影响可能较理论位置上移.

Pre-stressed concrete box girders with corrugated steel webs are used in Yuchun Bridge on the freeway around Nanjing in Jiangsu province. Recent research of this new box girder form mainly focuses on model test and FEM numerical analysis rather than in-situ test. A field test method was applied by considering the structural characteristics of Yuchun Bridge. Then the bending,shear and torsional properties were discussed based on the deformation and normal strain test data of the box girders with corrugated steel webs. The result shows that the field test results match well with the theoretical ones. The normal strains of the concrete top-slab and bottom-slab agree with the ' quasi plane assumption',and the normal strain of steel webs is smaller. The shear lag effect can be discovered according to the normal strain level. Aadditional normal stress and asymmetrical deformation are caused by the constraint torsion. Compared with theoretical results,the actual neutral axis may be moved up on of bump wall and surrounding structures.