配置600 MPa高强钢筋混凝土梁跨中挠度试验研究及计算方法

Experimental study and calculation method of mid-span deformation of RC beams with 600 MPa steel bars

为研究配置600 MPa高强钢筋混凝土梁的跨中挠度及其计算方法,设计了6组12根受弯梁,主要变化参数为配筋率和混凝土强度,对其进行静力受弯试验。分析了正常使用阶段各级荷载下的截面高度方向混凝土应变与纵向受力钢筋应变、荷载-跨中挠度全过程曲线等。试验结果表明:配置600 MPa级高强钢筋的混凝土梁混凝土的应变变化符合平截面假定,荷载-跨中挠度全曲线为三折线。基于已有的配置335、400、500 MPa钢筋混凝土梁的跨中挠度试验结果的分析,结合600 MPa试验研究,对国内外现行的规范中钢筋混凝土梁跨中挠度计算公式的适用性进行了比较分析,表明现行规范公式适用于配置335~400 MPa钢筋的混凝土梁。建立了适用于配置不同强度(335~600 MPa)钢筋及不同强度(C40~C60)混凝土梁跨中挠度的统一计算方法。

In order to study the mid-span deflection and its calculation method for reinforced concrete beams with 600 MPa high strength steel rebars, six groups of twelve beams were designed. The main variable parameters were the reinforcement ratio and concrete strength, and the static bending tests were performed. The strain variation of concrete along the beam depth and that of the longitudinal tensile steel rebars under various loads in the service stage was examined, and the complete load-mid-span deformation curves were experimentally analyzed. The experimental results show that, the strain distribution of the concrete conforms to the assumption of plane section, the load-deformation curves follow a tri-linear pattern. Furthermore, based on the existing analysis of the experimental results of the RC beams with 335 MPa, 400 MPa, and 500 MPa steel rebars, together with those with 600 MPa steel rebars, the applicability of the existing formulas from the domestic and foreign codes for RC beams was analyzed. It is shown that the current code formula is suitable for 335-400 MPa concrete beams. New uniform calculation methods were proposed, and the results show that the proposed formulas agree well with the test data and are suitable for the RC beams with different steel rebars(from 335 MPa to 600 MPa) and different concrete strengths(from C40 to C60).