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在预应力混凝土简支梁中,预应力钢筋(钢丝束)从中间走向支点处时,应逐渐弯起,以减小压力的偏心来配合弯矩的变化。曲线配筋设计得妥,可以抵消大部分或全部恒载剪力甚至部分活载剪力。目前,常见的是用圆弧线来设计曲线配筋,但是这种曲线是否符合力筋实际工作状态呢?我们知道,力筋在逐渐向上弯起时它的曲率变化应该是协调而连续的,这对较粗的钢筋则更是这样的,根据曲率公式: 1/R=(|y~″|)/((1+y~(′2)~(3/2))我们计算出以下几种曲线的曲率半径与水平
In the prestressed concrete simply supported beam, when the prestressed steel bar (steel wire bundle) moves from the middle to the fulcrum, it should be gradually bent to reduce the eccentricity of the pressure to match the change of the bending moment. The well-designed curve reinforcement can offset most or all of the constant-load shear forces and even some of the live-load shear forces. At present, it is common to use circular arcs to design curved reinforcements. However, does the curve conform to the actual working conditions of the tendons? We know that the curvature of the tendons should be coordinated and continuous when they are gradually bent upwards. This is even more true for coarser reinforcements. According to the curvature formula: 1/R=(|y~"||/((1+y~(’2)~(3/2)) we calculate the following Curve radius and level of the curve