预应力RPC箱梁受弯性能试验研究
发布时间：2018-09-04 16:14
【摘要】：活性粉末混凝土RPC(Reactive Powder Concrete)作为超高性能混凝土的一种,具有强度高、韧性大和耐久性能优异等特点,具有良好的应用前景。目前国内外学者对RPC梁的正截面受力性能进行了较多研究,但主要针对T梁和矩形截面梁,对RPC箱梁的研究很少,且均未涉及箱梁顶板横向预应力对梁抗弯性能的影响。基于此,本文通过对2片预应力RPC箱梁进行抗弯性能试验,试验研究了RPC箱梁的受力变形特征以及顶板横向预应力对其受弯性能的影响。具体研究内容如下:(1)试验结果表明:预应力RPC箱梁具有良好的变形能力,其极限变形可超过跨径的1/50;其正常使用阶段的裂缝宽度和短期刚度可参照《纤维混凝土结构技术规程》(CECS 38:2004)的相应公式计算,但其中的钢纤维影响系数可分别取为0.4和0.2。RPC箱梁顶板内的横向预应力对截面抗弯承载力的影响较小,但会使受压区混凝土的应变分布更加均匀从而使箱梁顶板受压的剪力滞效应减弱并增加构件的延性。就所试验的情形而言:顶板内施加2.95MPa的横向预压应力(仅为RPC棱柱体抗压强度94MPa的3.1%)后,可使箱梁受压翼缘的有效分布宽度增加约10%、构件延性指标增加约3%。试验结果验证了提出的预应力RPC箱梁正截面抗裂和抗弯承载能力计算公式。(2)编制非线性程序对箱梁全过程受力性能进行了分析,试验结果验证了该程序的有效性,并运用此程序对预应力RPC箱梁的受力性能进行了参数分析。结果表明:预应力配筋率对开裂弯矩、极限承载力和延性均有影响,RPC抗压强度、极限压应变、预应力张拉系数和受压区普通钢筋配筋率对延性有所影响。(3)运用有限元分析软件ABAQUS对预应力RPC箱梁受弯性能进行数值模拟,并与试验结果进行印证,同时对顶板施加横向预压应力进行有限元分析。结果表明:横向预应力的约束作用对箱梁顶板的纵向正应力有一定的卸载作用,使受压区混凝土的应变分布更加均匀从而使箱梁顶板受压的剪力滞效应减弱。
[Abstract]:As a kind of ultra-high performance concrete, reactive powder concrete (RPC (Reactive Powder Concrete) has the characteristics of high strength, high toughness and excellent durability, so it has a good application prospect. At present, scholars at home and abroad have done more research on the normal section behavior of RPC beam, but mainly for T beam and rectangular section beam, there are few researches on RPC box girder, and none of them involves the influence of transverse prestress on the flexural behavior of box girder. Based on this, the flexural behavior of two prestressed RPC box girders is tested, and the deformation characteristics of RPC box girders and the influence of transverse prestress on the flexural behavior of RPC box girders are studied. The specific research contents are as follows: (1) the experimental results show that the prestressed RPC box girder has good deformation capacity. Its ultimate deformation can exceed 1 / 50 of span. The crack width and short term stiffness in normal service can be calculated with reference to the corresponding formula of CECS 38: 2004. However, the influence coefficient of steel fiber can be taken as 0.4 and 0.2.RPC box girder roof transverse prestressing has little effect on the flexural bearing capacity of the section. However, the strain distribution of concrete in compression zone will be more uniform, and the shear lag effect of box girder roof compression will be weakened and the ductility of the member will be increased. As far as the test is concerned, when the transverse preloading stress of 2.95MPa is applied to the roof (only 3.1% of the compressive strength 94MPa of the RPC prism), the effective distribution width of the compressed flange of the box girder can be increased by about 10%, and the ductility index of the component can be increased by about 3%. The experimental results verify the formulas proposed for calculating the crack resistance and flexural bearing capacity of the normal section of prestressed RPC box girder. (2) the nonlinear program is compiled to analyze the mechanical behavior of the box girder during the whole process. The experimental results verify the effectiveness of the program. The parameters of prestressed RPC box girder are analyzed by using this program. The results show that the ratio of prestressed reinforcement has influence on the cracking moment, ultimate bearing capacity and ductility of RPC. The tensioning coefficient of prestress and the reinforcement ratio of common reinforcement in compression zone have some influence on ductility. (3) the flexural behavior of prestressed RPC box girder is simulated by using finite element analysis software ABAQUS, and the experimental results are verified. At the same time, the finite element analysis of the transverse preloading stress on the roof is carried out. The results show that the constraint of transverse prestress has a certain unloading effect on the longitudinal normal stress of the roof of the box girder, and the strain distribution of concrete in the compression zone is more uniform, thus the shear lag effect of the box girder roof is weakened.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446.1
[Abstract]:As a kind of ultra-high performance concrete, reactive powder concrete (RPC (Reactive Powder Concrete) has the characteristics of high strength, high toughness and excellent durability, so it has a good application prospect. At present, scholars at home and abroad have done more research on the normal section behavior of RPC beam, but mainly for T beam and rectangular section beam, there are few researches on RPC box girder, and none of them involves the influence of transverse prestress on the flexural behavior of box girder. Based on this, the flexural behavior of two prestressed RPC box girders is tested, and the deformation characteristics of RPC box girders and the influence of transverse prestress on the flexural behavior of RPC box girders are studied. The specific research contents are as follows: (1) the experimental results show that the prestressed RPC box girder has good deformation capacity. Its ultimate deformation can exceed 1 / 50 of span. The crack width and short term stiffness in normal service can be calculated with reference to the corresponding formula of CECS 38: 2004. However, the influence coefficient of steel fiber can be taken as 0.4 and 0.2.RPC box girder roof transverse prestressing has little effect on the flexural bearing capacity of the section. However, the strain distribution of concrete in compression zone will be more uniform, and the shear lag effect of box girder roof compression will be weakened and the ductility of the member will be increased. As far as the test is concerned, when the transverse preloading stress of 2.95MPa is applied to the roof (only 3.1% of the compressive strength 94MPa of the RPC prism), the effective distribution width of the compressed flange of the box girder can be increased by about 10%, and the ductility index of the component can be increased by about 3%. The experimental results verify the formulas proposed for calculating the crack resistance and flexural bearing capacity of the normal section of prestressed RPC box girder. (2) the nonlinear program is compiled to analyze the mechanical behavior of the box girder during the whole process. The experimental results verify the effectiveness of the program. The parameters of prestressed RPC box girder are analyzed by using this program. The results show that the ratio of prestressed reinforcement has influence on the cracking moment, ultimate bearing capacity and ductility of RPC. The tensioning coefficient of prestress and the reinforcement ratio of common reinforcement in compression zone have some influence on ductility. (3) the flexural behavior of prestressed RPC box girder is simulated by using finite element analysis software ABAQUS, and the experimental results are verified. At the same time, the finite element analysis of the transverse preloading stress on the roof is carried out. The results show that the constraint of transverse prestress has a certain unloading effect on the longitudinal normal stress of the roof of the box girder, and the strain distribution of concrete in the compression zone is more uniform, thus the shear lag effect of the box girder roof is weakened.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446.1
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