活性粉末混凝土结构抗弯性能试验研究

发布时间：2018-02-12 16:06

本文关键词： 活性粉末混凝土受弯构件开裂弯矩抗弯承载力刚度与裂缝宽度　出处：《西南交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：活性粉末混凝土(Reactive Powder Concrete,简称RPC)是一种具有高强度、高韧性和高耐久性等优良性能的水泥基复合材料,具有广阔的应用前景。目前我国的研究主要集中在RPC材料性能方面,在RPC结构方面的研究较少。由于RPC抗拉强度高,弹性模量大,将之与钢正交桥叠合,只需要不大的厚度即可以显著增大正交异性板的弯曲刚度,从而明显减小叠合桥面板的自重。然而,将RPC应用于叠合桥面板前,还有许多基础工作要做。文中采用试验结合理论分析的方法对RPC板(含叠合板)的抗弯性能进行研究,主要工作及结论如下：根据20块RPC加筋板和16块钢-RPC叠合板的实测开裂弯矩,基于平截面假定,分别推导了二者的开裂弯矩计算公式。在此基础上,利用文中及他人的实测数据,采用回归分析,建立了RPC抗拉强度关于钢纤维体积掺量的计算公式。考虑到二者均属受弯构件,建立了开裂弯矩统一计算公式。针对RPC材料当水泥基开裂后钢纤维仍然可以承担拉力的特点,推导了RPC加筋板受拉区开裂后的应力折减系数的计算方法和受压区等效应力及等效受压区高度的计算方法。在此基础上,建立了RPC加筋板正截面抗弯承载力计算公式。同时,采用换算截面法,将钢板换算成等厚的混凝土板,指出钢-RPC叠合板中性轴分别位于钢板和混凝土板的两种受力模式,并分别得到了相应承载力计算公式。文章同时推导了RPC加筋板的界限相对受压区高度和界限配筋率。考虑了受拉区RPC的贡献,采用钢筋实测应变,求得正常使用阶段各级荷载下纵向钢筋拉力对压区RPC合力作用点的力矩。通过对参数的回归分析,推导了RPC加筋板刚度计算公式。考虑钢筋保护层厚度的影响,结合钢纤维混凝土裂缝宽度计算方法,建立RPC加筋板裂缝宽度计算公式。以钢-RPC叠合板实测弯矩-挠度曲线反算叠合板实测刚度。基于有效惯性矩法,通过数值逼近,求得叠合板有效刚度计算公式,从而得到叠合板挠度计算公式。忽略钢板与RPC板间滑移,通过引入裂缝开裂高度,参考钢纤维混凝土裂缝宽度计算方法,得到叠合板负弯矩作用下的裂缝宽度计算公式。
[Abstract]:Reactive Powder reinforced concrete (RPCs) is a kind of cement matrix composite with high strength, high toughness and high durability, which has a wide application prospect. At present, the research in China is mainly focused on the properties of RPC materials. Due to the high tensile strength and large elastic modulus of RPC, the flexural stiffness of orthotropic plates can be significantly increased by overlaying it with steel orthotropic bridges with only a small thickness. However, there is still a lot of basic work to be done before the application of RPC to the composite deck slab. In this paper, the flexural properties of RPC slab (including laminated slab) are studied by means of experimental and theoretical analysis. The main work and conclusions are as follows: according to the measured cracking moment of 20 RPC stiffened plates and 16 steel RPC composite plates, based on the assumption of the plane section, the formulas for calculating the cracking moment of the two plates are derived respectively. Based on the measured data and regression analysis, a formula for calculating the volume content of steel fiber in RPC tensile strength is established. It is considered that both of them are flexural members. A unified formula for calculating crack bending moment is established. According to the characteristics of steel fiber can still bear tensile force when cement base cracks in RPC material, In this paper, the calculation method of stress reduction coefficient after crack of RPC stiffened plate under tension and the calculation method of equivalent stress and height of equivalent compression zone in compression zone are derived. On the basis of this, the formula for calculating flexural bearing capacity of normal section of RPC stiffened plate is established. By using the method of conversion section, the steel plate is converted into concrete slab of equal thickness, and the neutral axis of steel-RPC composite slab is pointed out, which is located in two stress modes of steel plate and concrete slab, respectively. At the same time, the height of the limit relative to the compression zone and the limit reinforcement ratio of the RPC stiffened plate are derived. Considering the contribution of the RPC in the tensile zone, the measured strain of the steel bar is used. The moment of longitudinal steel bar tension acting on the RPC joint force in compression zone under various loads in normal service stage is obtained. By regression analysis of the parameters, the stiffness calculation formula of RPC stiffened plate is derived. The influence of the thickness of steel protection layer on the stiffness of RPC stiffened slab is taken into account. Based on the calculation method of crack width of steel fiber reinforced concrete (SFRC), the formula for calculating crack width of RPC stiffened plate is established. The measured stiffness of composite plate is calculated by using the measured moment of bending curve of steel RPC composite plate. Based on the effective moment of inertia method, the method of numerical approximation is used to calculate the stiffness of the composite plate. The formula for calculating the effective stiffness of composite plate is obtained, and the formula for calculating deflection of composite plate is obtained. The slip between steel plate and RPC plate is ignored, and the crack crack height is introduced to calculate the crack width of steel fiber reinforced concrete (SFRC). The formula for calculating crack width of composite plate under negative bending moment is obtained.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU37

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