摘要
采用三分点重复加载,对高速铁路中广泛应用的32m预应力混凝土简支箱梁进行了多级重复荷载下的模型试验,其测试内容主要包括箱梁的裂缝分布及裂缝宽度、荷载-跨中挠度曲线、混凝土应变和钢筋应变的分布等。结果表明:简支箱梁首先在跨中底板出现裂缝,然后缓慢向腹板扩展;在纯弯段,裂缝间距分布比较均匀;在施加荷载超过开裂荷载不多的情况下卸载,裂缝在预应力筋的作用下能够闭合;加载结束时箱梁已经达到承载力极限状态(破坏)的标志是弯曲挠度达到跨度的1/30,受拉主筋处最大裂缝宽度达到1.8mm;重复加载下的荷载-跨中挠度曲线的包络线有3个拐点,分别对应于混凝土开裂、钢筋屈服、预应力筋屈服;跨中截面钢筋应变和混凝土应变沿腹板基本符合平截面假定,跨中顶板和底板截面钢筋应变和混凝土应变沿截面横向分布呈现箱梁剪力滞的分布规律。
A simply supported prestressed concrete box model with span of 32 m which was widely applied in high-speed railway girder under repeated loading was tested, and the experiment was the three-point repeated loading. The experiment focused on the distribution and width of cracks, the load-mid-span deflection relation curve, and strain distributions of concrete and steel bars. The results show that the concrete cracks first appear in the bottom plate of the simply supported box girder, and then slowly extend to the web. In the area of pure bending, spacing distribution of cracks is relatively uniform. When the load is little bigger than the cracking load, cracks can be closed under the action of the prestressed tendons. The final damage phenomenon of box girder is the ratio of bending deflection to span is 1/30, and the maximum width of crack in the reinforcedbar area is 1.8 mm. Under the repeated loading, the envelope of load-deflection curve has three- inflection points, respectively corresponding to the cracking of concrete, the yield of steel bar, and the yield of prestressed strand wires. The strains of steel bars and concrete in the mid-span section along the web are basically consistent with plane section assumption. Strains of steel bars and concrete in the top plate and bottom plate along the transverse distribution show the shear lag phenomena.
出处
《建筑科学与工程学报》
CAS
北大核心
2013年第1期49-54,65,共7页
Journal of Architecture and Civil Engineering
基金
国家自然科学基金项目(51178350)
铁道部科技研究开发计划项目(2010G007-J)
上海市教委重点学科建设项目(J51502)
关键词
高速铁路
预应力混凝土
简支箱梁
重复荷载
跨中挠度
承载力
high-speed railway
prestressed concrete
simply supported box girder
repeatedloading
mid-span deflection
bearing capacity
