活性粉末混凝土梁斜截面抗剪承载力研究

Research on Shear Capacity of Reactive Powder Concrete Beam

作者: 专业:桥梁与隧道工程 导师:季文玉 年度:2007 学位:硕士  院校: 北京交通大学

关键词
★软化桁架模型理论 活性粉末混凝土梁 斜截面抗剪承载力 建议计算式

Keywords
Softened Truss Model Theory, Reactive Powder Concrete Beam, Shear Capacity, Proposed Formula
        目前我国主要集中研究活性粉末混凝土材料性能方面,对活性粉末混凝土结构方面研究较少,本文探索性的研究了活性粉末混凝土梁斜截面抗剪承载力,是活性粉末混凝土结构方面研究的重要部分。本文研究的基础是软化桁架模型理论,用软化桁架理论模型分析了普通混凝土梁受剪破坏的全过程,选取全过程中剪力荷载最大的状态为临界状态,把这个临界状态时的剪力荷载作为混凝土梁的抗剪承载力。将计算得出的抗剪承载力和试验数据进行对比,证明了软化桁架模型的分析方法是可行的。然后,分别研究了影响抗剪承载力各因素对混凝土梁抗剪承载力的影响,参考规范计算公式,提出了混凝土梁抗剪承载力的建议计算式。通过对建议式计算式值、规范公式计算值、实验实测值进行对比。得出建议式计算值和试验值符合得更好的结论。对活性粉末混凝土梁,采用和普通混凝土梁一样的研究方法,不同的是选取的临界状态不同,活性粉末混凝土梁选取的是主拉应力达到抗拉强度时的状态为临界状态,这样就忽略了钢筋的作用。同样分别研究了各因素对抗剪承载力的贡献,提出了活性粉末混凝土梁斜截面抗剪承载力建议式。通过对建议式计算值、软化桁架模型理论分析值进行对比,发现两者符合得较好。最后再用有限元分析方法进行了验证,有限元验证时选取受剪区梁高中部截面最大主拉应力达到抗拉强度时的状态为临界状态。有限元分析的临界值比建议式计算值略高一些,这就说明建议式计算值是偏于安全的,建议式是可靠的。虽然本文的研究并不能完全体现活性粉末混凝土梁的抗剪承载力,但建议式用于计算活性粉末混凝土梁的抗剪承载力是可行的,可为活性粉末混凝土梁的设计提供参考。
    At present, studies of Reactive Powder Concrete (RPC) in China mostly focus on material performance rather than structural design. In this paper, some tentative researches are made on the shear capacity of RPC beam, which is an important part of RPC structure research.The failure process of reinforced concrete(RC)beam under shear forces is analyzed based on softened truss model theory. The maximum shear force, which appears at the critical time of failure process, is considered as the bearing capacity. The analytical method of softened truss model theory is proved feasible by comparing the experimental data with calculated carrying capacity. The influencing factors of bearing capacity for RC beams are also analyzed. Some suggested formulas are proposed based on standard formula. After comparing the result of standard formula, proposed formula and experimental data, it is found that the proposed formula has a better agreement with testing data.The RPC beam has the same analyzing method as the common concrete beam, while the difference between each other occurs on the critical state. The time when principal tensile stress of RPC beam reaches the tensile strength limit is consider as the RPC critical state, meanwhile, the functions of reinforcing steel bar are ignored. Contributions of different factors are taken into consideration, and then the suggested bearing capacity formulas of oblique section for RPC beam are proposed. From calculation and comparisons, it shows that the standard formula and proposed formula match well with each other. In the end, the shear capacity is analyzed by finite element method, by which the limit is a little larger than that of proposed formula method. It testifies that the calculated results by proposed formula are more conservative, and the formula is reliable.The shear capacity of RPC beam cannot be entirely described in this paper, however, the proposed formula is reliable and feasible for calculation, which also provides reference for later design of RPC beam.
        

活性粉末混凝土梁斜截面抗剪承载力研究

中文摘要5-6
ABSTRACT6
引言10-16
    1.1 概述10
    1.2 活性粉末混凝土的研究状况10-11
    1.3 问题的提出11-12
    1.4 传统钢筋混凝土构件抗剪承载力的研究12-13
    1.5 软化桁架模型理论13-14
    1.6 本文研究方法以及预期达到的效果14-16
2 软化桁架模型理论方程的建立16-30
    2.1 软化桁架理论计算钢筋混凝土抗剪强度的方程式16-21
        2.1.1 应力平衡方程式17
        2.1.2 变形协调方程式17-18
        2.1.3 材料的应力-应变方程18-21
    2.2 钢筋混凝土微元体上应力的计算21-23
        2.2.1 剪应力τlt21-22
        2.2.2 竖向正应力σ_t22-23
        2.2.3 纵向应力σ_l23
    2.3 预应力的影响23-24
    2.4 剪跨比的影响—平截面假定的引用24-26
        2.4.1 桁架高度25
        2.4.2 弦杆的应变25-26
    2.5 软化桁架理论模型计算步骤26-30
3 普通混凝土梁斜截面抗剪承载力研究30-54
    3.1 无腹筋混凝土梁抗剪承载力研究30-39
        3.1.1 混凝土强度的影响32-33
        3.1.2 截面尺寸影响33-34
        3.1.3 纵筋率的影响34-35
        3.1.4 剪跨比的影响35-36
        3.1.5 无腹筋梁抗剪承载力公式的提出36-39
    3.2 有腹筋钢筋混凝土梁抗剪承载力研究39-47
        3.2.1 混凝土强度影响39-40
        3.2.2 配箍率的影响40-42
        3.2.3 剪跨比的影响42
        3.2.4 有腹筋梁抗剪承载力公式的提出42-47
    3.3 预应力混凝土梁抗剪承载力研究47-53
        3.3.1 无腹筋预应力混凝土抗剪承载力48-50
        3.3.2 有腹筋预应力混凝土抗剪承载力50-53
    3.4 本章小结53-54
4 RPC 梁抗剪承载力54-71
    4.1 用软化桁架模型计算RPC 梁和普通混凝土梁不同的一些条件54-57
        4.1.1 RPC 的受压本构关系54-55
        4.1.2 RPC 的受拉本构关系55-56
        4.1.3 计算临界状态的选取56-57
    4.2 无腹筋RPC 梁抗剪承载力研究57-61
        4.2.1 RPC 强度的影响57
        4.2.2 截面尺寸的影响57-58
        4.2.3 纵筋率的影响58
        4.2.4 剪跨比的影响58-59
        4.2.5 无腹筋RPC 梁抗剪承载力计算建议式的提出59-61
    4.3 有腹筋RPC 梁抗剪承载力研究61-66
        4.3.1 RPC 强度的影响61-62
        4.3.2 纵筋率的影响62
        4.3.3 剪跨比的影响62-63
        4.3.4 配箍率的影响63-64
        4.3.5 有箍筋RPC 梁抗剪承载力公式的提出64-66
    4.4 预应力RPC 梁抗剪承载力研究66-70
        4.4.1 无腹筋预应力RPC 梁抗剪承载力计算66-68
        4.4.2 有箍筋预应力RPC 梁抗剪承载力68-70
    4.5 本章小结70-71
5 RPC 梁抗剪承载力的有限元验证71-77
    5.1 有限元分析模型介绍71-73
    5.2 计算结果分析73-76
    5.3 本章小结76-77
6 结论和展望77-81
    6.1 主要结论77-79
        6.1.1 普通混凝土梁斜截面抗剪承载力建议计算式77-78
        6.1.2 RPC 梁斜截面抗剪承载力建议计算式78-79
    6.2 研究展望79-81
参考文献81-83
作者简历83-84


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