HRB500级钢筋活性粉末混凝土梁抗剪承载能力及剪切延性研究

The reactive powder concrete component is of high strength,small cross-section, light weight and high performance of corrosion and fire resistance which can be used to solve the carrying capacity and durability problems of high-rise and long-span structures.The objective of this project is to explore the collaborating shear resistance of high performance reactive powder concrete structure reinforced with high-strength HRB500 steel bars, and the possibility of further improving its shear carrying capacity and shear ductility.Through structural testing,applicant intends to adopt the revised pressure field and softened truss model theory,programming MATLAB to analyze the whole process of beam subjected to shear,supplemented by validation of non-linear finite element simulation to study shear resisting mechanism of reactive powder concrete beams reinforced with HRB500 steel bars. Applicant would also analysis main factors influencing shear performance for reactive powder concrete beams reinforced with HRB500 steel bars and its regulation. Based on the experiment and analysis,inclined cross section shear resistance computational theory will be established and key technical problems such as the boundary of the shear span ratio for failure mode, control of the crack width and the criterion of inclined angle development will be resolved.All these studies can provide the reference for speeding up engineering application of reactive powder concrete structure.

活性粉末混凝土构件强度高，截面小，自重轻，防腐和防火性能优异，可以较好地解决高层大跨建筑结构的承载能力及耐久性问题。本项目试图探究在高性能的活性粉末混凝土结构中配置高强度HRB500级钢筋的协同抗剪机理，以及提高钢筋混凝土构件抗剪承载能力和剪切延性的可行性。申请人拟通过结构试验，运用修正压力场和软化桁架模型等理论，编制MATLAB程序进行试验梁抗剪全过程分析，辅以非线性有限元模拟验证等手段，研究探讨HRB500级钢筋活性粉末混凝土梁的抗剪工作机理。考虑剪跨比、配箍率和纵筋配筋率等参数，兼顾钢纤维含量、钢筋等级、截面型式、水平腹筋作用效应等条件，分析HRB500级钢筋活性粉末混凝土梁抗剪性能的主要影响因素及其规律。在此基础上构建这种新型材料梁斜截面抗剪的计算理论,解决其破坏形态的剪跨比界限，裂缝宽度控制，倾角发展趋势等关键技术问题，为加快活性粉末混凝土结构的工程应用提供参考。

活性粉末混凝土是一种超高性能水泥基复合材料，在活性粉末混凝土构件中配置高强HRB500级钢筋，能够充分发挥材料特性，高效节能。项目以剪跨比、配箍率、钢纤维含量、纵筋配筋率、箍筋形式、预应力度、截面形式和加载方式等为参数，进行3批共46根梁的结构试验并获得数据，运用塑性极限方程和修正压力场等理论模型进行验证，分析HRB500级钢筋活性粉末混凝土梁的受剪机理。主要成果包括：1）剪跨比对构件的极限承载力、主斜裂缝倾角和破坏形态影响最大，抗剪承载力随剪跨比的增大而减小，其对RPC梁破坏状态的影响有别于普通混凝土梁，剪跨比1.51时已表现出斜压破坏特征，剪跨比3.02仍然呈现剪压破坏特征；2）配箍率对弯剪段斜裂缝的分布形态影响较大，配箍率较低时构件的破坏端基本都有一条由支座处指向加载点处的主斜裂缝，其端部隔离体几乎不存在受压区。配箍率较高时则无明显主斜裂缝，裂缝数量多且细而密，抗剪承载力随配箍率的提高而增大；3）钢纤维可有效阻碍裂缝的发展，提高构件的开裂荷载与剪切延性，当钢纤维体积率由0增大到2%时，配箍率由0.25%提高到0.75%，构件的剪切延性明显提高；4）纵筋率对构件抗剪性能的影响不太明显，其承载力随配筋率的提高而增大；5)箍筋形式对高强钢筋RPC梁抗剪承载力提升的影响因素依次为斜向箍筋＞垂直腹筋＞水平腹筋；6)预应力RPC梁的抗剪承载能力随剪跨比的增大而减小，随预应力度的增大而增大。延性则随剪跨比的增大而增大，随预应力度的增大而减小；7）T形截面RPC梁的抗剪承载力高于矩形截面梁,翼缘能有效抑制斜裂缝宽度的发展；8）间接加载RPC梁抗剪极限承载力的降低程度明显低于普通混凝土梁，挑耳在上和挑耳与梁等高梁的极限承载力与直接加载梁相当，挑耳在下梁的极限承载力比直接加载梁降低25%左右；9）基于塑性理论推导出有腹筋RPC梁适合于工程计算的抗剪承载力简化公式；10）构建了基于修正压力场理论的配筋 RPC梁分析模型，求解出全受力过程中截面平均应力、应变随梁端剪力变化的规律，并得出最终极限承载力。研究成果可以为活性粉末混凝土结构的工程应用提供参考。