【《某混凝土简支T梁桥钢束预应力损失计算过程案例》3000字】

由预应力钢筋应力松弛引起的预应力损失钢铰线由松弛引起的应力损失的终极值，按下式计算：：张拉系数，采用一次张拉，；：钢筋松弛系数，对于低松弛钢筋，；：传力锚固时的钢筋应力，对后张法构件，计算四分点截面钢绞线由松弛引起的应力损失见表5-4。表5-4四分点截面计算表钢束号110.318601178.049924.486721100.351315.714131103.584916.05941175.787724.217混凝土的收缩和徐变引起的预应力损失由混凝土收缩和徐变引起的预应力损失可按下式计算：：受拉区全部纵向钢筋截面重心处由混凝土收缩和徐变引起的预应力损失；：钢束锚固时，全部钢束重心处由预加应力（扣除相应阶段的应力损失）产生的混凝土法向压应力，并根据张拉受力情况，考虑主梁重力的影响；：配筋率，；：钢束锚固时相应的净截面面积；：钢束群重心至截面净轴的距离；：截面回转半径，；：加载龄期为、计算龄期为t时的混凝土徐变系数；：加载龄期为、计算龄期为t时的混凝土收缩徐变。混凝土徐变系数终极值和收缩应变终极值的计算构件理论厚度的计算公式：：主梁混凝土截面面积；：构件与大气接触的截面周边长度。考虑混凝土收缩和徐变大部分在成桥之前完成，A和u均采用预制梁的数据。对于混凝土毛截面，跨中与四分点的截面上述数据完全相同，即。故由于混凝土收缩和徐变在相对湿度在80%条件下完成，受荷载时混凝土龄期为28天。查表得，。由于表中数值是按强度等级C40混凝土计算所得，而主梁为C50混凝土，所以查表所得数值应乘以，为混凝土轴心抗压强度标准值，对C50混凝土，，则，故，。计算混凝土收缩和徐变引起的预应力损失计算结果见表5-5。表5-5四分点截面混凝土收缩和徐变引起的预应力损失计算表计算数值////44508.43663143.821162.92323890955.04///6932.63582.6241950005.75计算应力损失值6.41998.640115.16001.752140.66703457.21810.000122.86620342.80.0060680.9[(1)+(2)]165.23031.2055计算数据成桥后四分点截面由张拉钢束产生的预加力作用效应计算计算方法与预加应力阶段混凝土弹性压缩引起的预应力损失计算方法相同，其计算结果见表5-6。表5-6成桥后四分点截面由张拉钢束产生的预加力作用效应计算表计算数据////8351.399.9129238548.85113.095.76钢束号锚固时预加纵向力//预加弯矩/锚固时钢束应力41025.164100461.0000001003510046103.961034523103452311027.1543100660.98254599802003649.7248676215212843961.11294181.000000942729454103.9896988024911642958.226993900.98772393583882288.228171473308310预应力损失汇总及预加力计算汇总结果见表5-7。表5-7钢束预应力损失总表截面钢束号预加应力阶段正常使用阶段锚固时预应力损失锚固时钢束应力锚固后预应力损失钢束有效应力四分点112.1491.2721.951188.1525.48126.511027.15229.7590.7582.551110.4616.71958.22351.1390.2458.451113.6917.05961.11440.1587.3601185.8925.211025.16跨中162.2130.331.551189.4525.64131.761023.04262.329.8695.781125.5718.38966.42362.396429.424368.93441152.774921.365990.6475451.519637.046301224.854129.98071054.111支点10.4238152.23312.80951148.063620.832276.68131041.550120.5196151.649318.12831143.232818.28971037.261830.6155151.068617.46941144.376520.41781038.277440.604137.684701175.131323.9441065.506施工阶段传力锚固应力及其产生的预加力可按如下方法计算。传力锚固时，。由产生的预加力：纵向力：弯矩：剪力：计算结果见表5-8。表5-8（1）预加力作用效应计算表截面钢束号预加力阶段由预应力钢束产生的预加力作用效应四分点10.1218730.99254611535.1211145.9147140.5673525.078420.0674310.99772410773.67471075.915772.6394906.85130110805.3651081.536601081.836940111512.95151152.295301152.6152∑4452.329213.20673663.0485跨中10111547.78071155.77820881.617420110921.80171093.18030964.930730111188.3481119.834901122.702140111894.72421190.472501193.5207∑4555.932604159.4379支点10.1218680.99254511142.17731106.9133135.7751-390.136220.1218680.99254511094.83541102.2145135.198558.605130.1218680.99254511106.04371103.3271135.3351506.194840.08715560.99619411407.44071137.403899.4127908.3385∑4446.5256505.72181079.6692表5-8（2）预加力作用效应计算表截面钢束号使用阶段由预应力钢束产生的预加力作用效应四分点10.1218710.99254510066.1531000.1291123.7757487.880620.0674310.9977239390.6782937.930864.4248818.25883019418.9884942.89880970.996140110046.62651005.662701035.6325∑3883.2884187.08953309.435跨中10110025.91421003.59140791.04352019471.0019948.10020860.95643019708.3775971.83770998.996740110330.31981034.031901062.931∑3954.228203710.5946支点10.1218680.99254510207.2231014.1147125.4919-307.074120.1218680.99254510165