UHPC加固箱梁顶板受弯性能试验研究

发布时间：2018-11-20 07:49

【摘要】：提出密配筋UHPC(超高性能混凝土)加固钢筋混凝土箱梁顶板方法,以消除混凝土箱梁顶板因开裂导致结构承载能力和耐久性普遍降低两类病害.为探究该加固方法在集中荷载下的箱梁顶板横向受弯性能,对3块足尺箱梁顶板局部模型进行试验研究.试验结果表明:负弯矩作用下,受拉的UHPC层显著提高了加固板的抗裂性能和刚度;加固试验板的开裂强度取决于UHPC的弹性抗拉性能;裂缝宽度为0.2mm时的持荷水平相对于未加固试验板提高了255.8%;当裂缝宽度小于0.27mm时,荷载与最大裂缝宽度关系近似线性.正弯矩作用下,UHPC层受压,加固试验板的开裂强度取决于封闭裂缝所用黏胶的抗拉强度;因为普通混凝土区域裂缝出现较早,正弯矩加固板在前期表现出略微偏大的挠度,但后期挠度和裂缝宽度的增长速度均明显小于未加固板,致密的UHPC层为箱梁顶板提供良好的防水性能,加固层对正弯矩试验板刚度的提高和裂缝发展的控制效果较为明显;破坏形态符合预期,破坏荷载与理论计算结果吻合良好.
[Abstract]:A method of strengthening reinforced concrete box girder roof with dense reinforced UHPC (ultra-high performance concrete) is presented in order to eliminate two kinds of diseases, such as structural bearing capacity and durability reduction caused by cracking of concrete box girder roof. In order to investigate the transverse bending behavior of the roof of the box girder under concentrated load, the local model of the roof of three full-scale box girders was tested and studied. The experimental results show that the tensile UHPC layer significantly improves the crack resistance and stiffness of the strengthened plate under negative bending moment, and the cracking strength of the strengthened plate depends on the elastic tensile property of UHPC. When the crack width is 0.2mm, the load holding level is 255.88.When the crack width is smaller than 0.27mm, the relationship between the load and the maximum crack width is approximately linear. Under the action of positive bending moment, the cracking strength of the test plate strengthened by UHPC layer depends on the tensile strength of the adhesive used to seal the crack. Because the cracks appeared earlier in the common concrete area, the positive bending moment strengthened slab showed slightly larger deflection in the early stage, but the growth speed of the deflection and crack width in the later stage was obviously lower than that of the unstrengthened slab. The compact UHPC layer provides a good waterproof performance for the box girder roof, and the strengthened layer can improve the stiffness of the positive bending moment test plate and control the crack development obviously. The failure pattern is in line with the expectation, and the failure load is in good agreement with the theoretical calculation results.
【作者单位】：湖南大学风工程与桥梁工程湖南省重点实验室;湖南省交通规划勘察设计院;
【基金】：国家自然科学基金资助项目(751201208) 湖南省交通运输厅科技进步与创新项目(201425)~~
【分类号】：U445.72

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