摘要
中强(1270MPa)螺旋肋钢丝是我国研制开发的预应力钢筋新品种,具有强度高、延性好、与混凝土粘结锚固可靠的优点,以这种钢丝为配筋的预应力空心板具有良好的力学性能,是传统用于预应力混凝土空心板的冷加工钢丝的理想替代品。
运用钢筋混凝土受弯构件非线性全过程分析的基本原理,本文编制了中强螺旋肋钢丝预应力混凝土空心板的数值分析程序。计算结果与试验结果进行对比,符合较好。数值分析程序验证了中强螺旋肋钢丝预应力混凝土空心板的工作阶段也可分为弹性工作阶段、带裂缝工作阶段和破坏阶段。
运用数值分析程序计算了175组不同跨高比、配筋率、张拉控制应力的中强(1270MPa)螺旋肋钢丝预应力空心板,结果表明跨高比、配筋率、张拉控制应力是影响空心板破坏形态的主要因素,且构件挠跨比与跨高比和张拉控制应力呈线性关系,与配筋率呈二次抛物线关系。进而通过回归分析,得出了挠跨比与以上三因素数量关系的回归方程。
以极限挠度达到跨度的1/50作为延性破坏的判定指标,本文分别运用数值分析程序试算和回归方程得出了常用跨度、常用配筋的中强(1270MPa)螺旋肋钢丝预应力混凝土空心板的张拉控制应力的取值,供设计参考。
As a new variety of steel wire in our country, the mid-strength (1270MPa) spiral-ribs steel wire has many excellences such as high strength, good ductility, credible felting and anchoring capability witn concrete and so on. The pre-stressed concrete slab with this sort of steel wire has good mechanical property. So it is an ideal substitute to the cold-processed wires traditionally adopted in pre-stressed concrete slabs.
Based on the nonlinear analysis theory of the reinforced concrete flexural member, this paper explores a numerical analysis program for the pre-stressed and hollow-core concrete slabs with mid-strength spiral-ribs steel wires. Contrast with the experimental results which were made by Wei Xing of Zhengzhou University of Technology, the numerical analysis results show a good agreement with the experimental results. Thus the numerical analysis testifies that the service stages of the pre-stressed and hollow concrete slabs with mid-strength spiral-ribs steel wires can also be separated to the elastic stage, cracking stage and failure stage.
175 slabs with different parameters such as the ratio of span to rise, the ratio of reinforcement and the stretching controlling stress are analyzed by the numerical analysis program. The results indicate that the ratio of span to rise, the ratio of reinforcement and the stretching controlling stress are the three primary influencing factors to the failure pattern of the slab. In addition, the relationships between the ratio of deflection to span and the ratio of span to rise and the stretching controlling stress submit to linear curves, the relationship between the ratio of deflection to span and the ratio of reinforcement submits to a quadratic parabola curve. Furthermore, using the regress analysis method, the regress equation of the ratio of deflection to span and the above three parameters are resulted.
Taking an ultimate deflection more than 1/50 of calculating span as the determinant term, by the means of numerical analysis and regress equation
respectively, this paper discusses the reasonable stretching controlling stress of usual span and reinforcement slabs for design reference.
引文
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