發(fā)布時(shí)間：2018-09-04 16:14

【摘要】：活性粉末混凝土RPC(Reactive Powder Concrete)作為超高性能混凝土的一種,具有強(qiáng)度高、韌性大和耐久性能優(yōu)異等特點(diǎn),具有良好的應(yīng)用前景。目前國內(nèi)外學(xué)者對RPC梁的正截面受力性能進(jìn)行了較多研究,但主要針對T梁和矩形截面梁,對RPC箱梁的研究很少,且均未涉及箱梁頂板橫向預(yù)應(yīng)力對梁抗彎性能的影響。基于此,本文通過對2片預(yù)應(yīng)力RPC箱梁進(jìn)行抗彎性能試驗(yàn),試驗(yàn)研究了RPC箱梁的受力變形特征以及頂板橫向預(yù)應(yīng)力對其受彎性能的影響。具體研究內(nèi)容如下:(1)試驗(yàn)結(jié)果表明:預(yù)應(yīng)力RPC箱梁具有良好的變形能力,其極限變形可超過跨徑的1/50;其正常使用階段的裂縫寬度和短期剛度可參照《纖維混凝土結(jié)構(gòu)技術(shù)規(guī)程》(CECS 38:2004)的相應(yīng)公式計(jì)算,但其中的鋼纖維影響系數(shù)可分別取為0.4和0.2。RPC箱梁頂板內(nèi)的橫向預(yù)應(yīng)力對截面抗彎承載力的影響較小,但會(huì)使受壓區(qū)混凝土的應(yīng)變分布更加均勻從而使箱梁頂板受壓的剪力滯效應(yīng)減弱并增加構(gòu)件的延性。就所試驗(yàn)的情形而言:頂板內(nèi)施加2.95MPa的橫向預(yù)壓應(yīng)力(僅為RPC棱柱體抗壓強(qiáng)度94MPa的3.1%)后,可使箱梁受壓翼緣的有效分布寬度增加約10%、構(gòu)件延性指標(biāo)增加約3%。試驗(yàn)結(jié)果驗(yàn)證了提出的預(yù)應(yīng)力RPC箱梁正截面抗裂和抗彎承載能力計(jì)算公式。(2)編制非線性程序?qū)ο淞喝^程受力性能進(jìn)行了分析,試驗(yàn)結(jié)果驗(yàn)證了該程序的有效性,并運(yùn)用此程序?qū)︻A(yù)應(yīng)力RPC箱梁的受力性能進(jìn)行了參數(shù)分析。結(jié)果表明:預(yù)應(yīng)力配筋率對開裂彎矩、極限承載力和延性均有影響,RPC抗壓強(qiáng)度、極限壓應(yīng)變、預(yù)應(yīng)力張拉系數(shù)和受壓區(qū)普通鋼筋配筋率對延性有所影響。(3)運(yùn)用有限元分析軟件ABAQUS對預(yù)應(yīng)力RPC箱梁受彎性能進(jìn)行數(shù)值模擬,并與試驗(yàn)結(jié)果進(jìn)行印證,同時(shí)對頂板施加橫向預(yù)壓應(yīng)力進(jìn)行有限元分析。結(jié)果表明:橫向預(yù)應(yīng)力的約束作用對箱梁頂板的縱向正應(yīng)力有一定的卸載作用,使受壓區(qū)混凝土的應(yīng)變分布更加均勻從而使箱梁頂板受壓的剪力滯效應(yīng)減弱。
[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.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U446.1

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