论文部分内容阅读
对于部分预应力砼梁裂缝宽度计算和疲劳验算,需要求解中和轴高度x的三次方程,从而求得危险开裂截面的钢筋应力和砼应力,这是相当繁琐的。对于ζ=x/h_p=0.18～0.90(h_p——预应力钢筋重心至截面受压边的距离),本文建议了一个“分区降阶逼近法”,推导出求解ζ的一次方程,从而使x、钢筋应力和砼应力的计算得到简化。 为了提高计算精度,本文还给出了将三次方程分区降阶为二次方程的方法。根据设计要求,也可将二次方程与一次方程联合应用。对于区间可以缩小的ζ,如ζ=0.23～0.90,ζ=0.36～0.90,可以分别采用本文建议的二次方程或一次方程。此外,还提出适合于区间ζ=0.15～0.90的二次方程。 对偏心受压、偏心受拉构件中求解x的三次方程问题,也可采用本文建议的方法。
For the calculation of the crack width of the partially prestressed truss beam and the fatigue checking, the cubic equation of the height x of the neutral axis needs to be solved, so that the stress of the steel bar and the barium stress of the dangerous cracking section can be obtained, which is quite tedious. For ζ=x/h_p=0.18～0.90 (h_p——distance between the center of gravity of the prestressed steel bar and the compression edge of the cross section), this paper proposes a “partitioned reduced order approximation method” to derive a linear equation for solving the ζ, so that x The calculation of steel stress and bar stress is simplified. In order to improve the calculation accuracy, this paper also gives the method of reducing the cubic equation to the quadratic equation. According to the design requirements, the quadratic equation can also be combined with the first equation. For the interval where the interval can be reduced, such as ζ = 0.23-0.90, ζ = 0.36-0.90, the quadratic equation or the first-order equation proposed in this paper can be used. In addition, a quadratic equation suitable for the interval ζ=0.15 to 0.90 is also proposed. For the solution to the cubic equation of x in eccentric compression and eccentric tension members, the method proposed in this paper can also be used.