部分预应力钢骨超高强混凝土梁抗弯性能研究

发布时间：2018-02-26 17:14

本文关键词： 部分预应力梁钢骨超高强混凝土抗弯性能疲劳荷载　出处：《大连理工大学》2014年博士论文　论文类型：学位论文

【摘要】：采用超高强混凝土材料,同时应用钢骨混凝土和部分预应力技术形成了一种新型的组合梁——部分预应力钢骨超高强混凝土梁。该型式的组合梁利用了超高强混凝土抗压强度高、耐久性优异和可有效控制截面等特点,提高梁的配筋率、承载能力、耐久性和减轻自重；利用部分预应力技术提高了梁正常使用极限状态下的抗裂性能,并且部分预应力技术相比全预应力技术更加有利于梁的延性性能；利用内置钢骨改善了超高强脆性破坏导致极限承载力状态后承载力骤降的现象,改善梁的延性性能和耗能能力。因此,部分预应力钢骨超高强混凝土梁非常适用于大跨重载桥梁和超高层建筑结构转换梁。目前,仅有我国对预应力钢骨混凝土结构已经开展了一定的研究,取得了一些成果。但对于部分预应力钢骨超高强混凝土结构的研究文献报道较少。本文采用试验研究、理论分析与数值模拟计算相结合的方法,对部分预应力钢骨超高强混凝土梁的静力荷载和疲劳作用下的抗弯性能进行了研究。本文所做的主要工作如下： (1)进行了4根部分预应力超高强混凝土梁静力荷载下的抗弯性能试验。研究了预应力筋高度和预应力筋配筋率对试件受弯性能的影响。试验结果验证了试件平截面假定的成立,依据现行混凝土结构设计规范中的抗弯计算理论,给出了部分预应力超高强混凝土梁的正截面抗弯承载力计算公式。依据现行规范中的裂缝宽度计算理论,通过引入预应力筋高度对等效直径的影响系数k1和对构件特征系数acr的修正,给出了部分预应力超高强混凝土梁的最大裂缝宽度计算公式。 (2)进行了20根部分预应力钢骨超高强混凝土梁静力荷载下的抗弯性能试验。研究了试件的破坏形态、荷载一挠度曲线、跨中截面应变和裂缝开展模式,系统分析了预应力筋张拉控制应力、非预应力受拉钢筋配筋率、钢骨偏心率、钢骨含钢率、预应力筋高度和预应力筋配筋率等试验因素对试件承载力、抗弯刚度和弯曲延性的影响规律。依据现行的两种钢骨混凝土结构设计计算理论,分别给出了基于截面变形协同分析法和叠加法的部分预应力钢骨超高强混凝土梁的正截面抗弯承载力计算公式,并对两种计算方法的适用性进行了对比分析。采用分阶段刚度叠加法并考虑了核心约束混凝土的刚度贡献,提出了部分预应力钢骨超高强混凝土梁各阶段的截面刚度计算公式,进而采用结构力学计算方法给出了试件的跨中挠度计算公式。引入了预应力筋、钢骨下翼缘和腹板位置对等效直径的影响系数k11、k2和k3,给出了部分预应力钢骨超高强混凝土梁的最大裂缝宽度计算公式。通过与部分预应力超高强混凝土梁的试验结果对比,分析了内置钢骨对试件的承载力、弯曲延性、能量消耗和裂缝开展模式的影响。 (3)提出了综合配筋指数的计算公式,采用综合配筋指数对18根部分预应力钢骨超高强混凝土梁和4根部分预应力超高强混凝土梁的抗弯受力性能进行分析。采用数理统计的方法,拟合出了综合配筋指数作为单一变量的部分预应力钢骨超高强混凝土梁的极限承载力、位移延性系数和正常使用极限状态所受弯矩等级的预测公式。 (4)结合试验结果,采用ANSYS有限元分析软件对部分预应力钢骨超高强混凝土梁的抗弯性能进行数值仿真分析。分析阶段为从开始加载到试件达到承载力极限状态,数值分析结果与试验结果基本一致,验证了ANSYS有限元模型的正确性。 (5)进行了4根部分预应力钢骨超高强混凝土梁和1根部分预应力超高强混凝土梁疲劳荷载下的抗弯性能试验。分析了试验梁的荷载-挠度曲线变化规律、抗弯刚度的退化规律、裂缝宽度扩展规律和非预应力受拉钢筋的拉应变随疲劳次数的变化规律。分别给出了试件刚度降低系数、最大裂缝宽度变化和非预应力受拉纵筋的应力幅值比与疲劳次数的关系曲线。上述曲线可用于预测部分预应力钢骨超高强混凝土梁的疲劳寿命。
[Abstract]:A new composite beam _ partial prestressed steel - bone ultra - high strength concrete beam is formed by using ultra - high strength concrete . The composite beam of this type has the characteristics of high compressive strength , excellent durability and effective control of cross section . At present , only China has carried out a certain research on prestressed reinforced concrete structure , and some results have been obtained . However , it has been reported less in the research literature of some prestressed reinforced concrete structures . The experimental research , theoretical analysis and numerical simulation are used to study the bending performance of some prestressed reinforced concrete beams under static load and fatigue . The main work is as follows : ( 1 ) The bending performance test under static load of 4 partial prestressed high strength concrete beams is carried out . The influence of the height of the prestressed tendon and the reinforcement ratio of the prestressed rib on the bending performance of the test piece is studied . The calculation formula of the bending bearing capacity of the positive section of the partially prestressed high strength concrete beam is given according to the theory of bending calculation in the current specification of the concrete structure . According to the calculation theory of crack width in the current specification , the calculation formula of the maximum crack width of the partially prestressed ultra - high strength concrete beam is given by introducing the influence coefficient k1 of the height of the prestressed rib on the equivalent diameter and the correction of the characteristic coefficient acr of the component . ( 2 ) The bending performance test under static load of 20 partial prestressed reinforced concrete beams is carried out . The formulas for calculating the flexural rigidity and bending ductility of partial prestressed reinforced concrete beams based on cross section deformation cooperative analysis method and superposition method are analyzed in this paper . ( 3 ) The calculation formula of composite reinforcement index is put forward , and the bending stress properties of 18 partial prestressed reinforced concrete beams and 4 partial prestressed high strength concrete beams are analyzed by using the comprehensive reinforcement index . The ultimate bearing capacity , displacement ductility coefficient and the normal use limit state of the partial prestressed reinforced concrete beams with the combined reinforcement index as a single variable are fitted by mathematical statistics . ( 4 ) Based on the experimental results , the bending performance of some prestressed reinforced concrete beams is analyzed by ANSYS finite element analysis software . The analysis stage is from the beginning to the test piece to reach the ultimate bearing capacity limit state . The numerical analysis results are basically consistent with the experimental results , and the correctness of the ANSYS finite element model is verified . ( 5 ) The bending performance test of four partial prestressed reinforced concrete beams and one partial prestressed high strength concrete beam under fatigue loading is carried out . The variation law of the load - deflection curve of the test beam , the deterioration rule of the flexural rigidity , the crack width expansion law and the tensile strain of the non - prestressed tensile steel bar are analyzed . The relation curves of the stiffness reduction coefficient , the maximum crack width change and the stress amplitude ratio and the fatigue frequency of the non - prestressed tensile steel bar are respectively presented . The curve can be used to predict the fatigue life of the partially prestressed reinforced concrete beam .

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU398.9

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