温度场和温度应力计算.doc
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1、附计算书3:温度场和温度应力计算一、温度场计算计算以本工程1.2m厚底板为例,用差分法计算底板28d水化热温升曲线。计算中各参数的取值如下:每m3胶凝材料用量,440kg/ m3; Q胶凝材料水化热总量(kJ/kg);,本例采用实测值260kJ/kg;混凝土的比热,取1.0kJ/ (kg); 混凝土的质量密度,取2400kg/ m3;导温系数,取0.0035m2/h;m,取0.5。混凝土的入模温度取10,地基温度为18,大气温度为18。温度场计算差分公式如下: (B.4.2-1)试算、,确定。取 = 0.5天 = 12小时, = 0.4m,即分3层则,可行。代入该值得出相应的差分法公式为画出相
2、应的计算示意图,并进行计算。底板厚1.2m,分3层,每层0.4m,相应的计算示意如下图。从上至下各层混凝土的温度分别用、表示,相应时刻各层的温度即为、。混凝土与大气接触的上表面边界温度用表示,与地基接触的下表面边界温度用表示。 = 0,即第天,上表面边界,取大气温度, = 18各层混凝土温度取入模温度,即= = = 10下表面边界,取地基温度,= 18; = 1,即第天,温升10.544上表面边界温度,散热温升为0,始终保持不变, = 18 第一层混凝土温度,见计算图示中方框1,的边界为和,在的基础上考虑温升,即第二层混凝土温度,见计算图示中方框2,的边界为和,在的基础上考虑温升,即第三层混凝
3、土温度,见计算图示中方框3,的边界为和,在的基础上考虑温升,即下表面边界温度,需要考虑散热温升,所以需每一步都需进行修正。见计算图示中方框6,的边界为和地基温度18,在的基础上考虑温升,即以上即完成了一遍 = 1时,各温度计算。同理 = 2,即第天,温升 = 8.212,上表面 = 18,同理可计算 = 356,即第1.528天的各层温度值,本算例中不再进行详细计算,最终计算结果如表1。表1 不同混凝土龄期下各层混凝土温度值(单位:)混凝土龄期上表面第一层第二层第三层底界边层018101010180.51822.64420.54422.64426.44411829.08529.85831.30
4、231.4411.51832.77336.42937.35434.27121834.83640.69341.28335.7902.51835.83343.18943.56536.44131836.10344.37844.61736.4913.51835.87644.62144.77436.12341835.31144.19844.29535.4694.51834.52743.31843.38034.62751833.60742.13842.17733.6715.51832.61540.77440.79932.65661831.59439.31339.32931.6206.51830.57737
5、.81637.82630.59471829.58536.32736.33429.5957.51828.63234.87834.88228.63981827.72933.48733.49027.7338.51826.88032.16932.17126.88291826.08830.93230.93326.0899.51825.35329.77729.77825.354101824.67628.70828.70824.67610.51824.05327.72027.72124.053111823.48226.81326.81323.48211.51822.96025.98225.98222.961
6、121822.48525.22225.22222.48512.51822.05224.53024.53022.052131821.65923.90023.90021.65913.51821.30323.32823.32821.303141820.98022.80822.80820.98014.51820.68722.33822.33820.687151820.42321.91221.91220.42315.51820.18321.52721.52720.183161819.96821.17921.17919.96816.51819.77320.86420.86419.773171819.597
7、20.58120.58119.59717.51819.43820.32420.32419.438181819.29520.09320.09319.29518.51819.16619.88519.88519.166191819.05019.69719.69719.05019.51818.94519.52819.52818.945201818.85119.37619.37618.85120.51818.76619.23819.23818.766211818.68919.11519.11518.68921.51818.62019.00319.00318.620221818.55818.90318.9
8、0318.55822.51818.50218.81318.81318.502231818.45218.73118.73118.45223.51818.40718.65818.65818.407241818.36618.59218.59218.36624.51818.32918.53318.53318.329251818.29618.48018.48018.29625.51818.26718.43118.43118.267261818.24018.38818.38818.24026.51818.21618.34918.34918.216271818.19418.31418.31418.19427
9、.51818.17518.28318.28318.175281818.15718.25418.25418.157二、温度应力计算示例以下计算示例按照步长为1天进行。1、里表温差T1计算公式如下 (B.5.1)计算结果见表2 各龄期混凝土收缩当量温差计算根据公式 (B.2.1) (B.2.2)其中 取4.010-4石家庄市内年平均气温值取14.5计算结果见表3 综合降温差T2计算公式如下 (B.5.2)计算结果见表2表2 综合温差计算结果混凝土龄期第一层(Tb)第三层(Tm)第三层(Td)T1(Tm- Tb)T2*T1*T201010100.0000.000/-8.6610.522.64422.
10、64422.6440.0008.6612.217 -8.803129.08531.30231.3022.21717.4652.365 -6.1711.532.77337.35437.3544.58123.6361.866 -4.127234.83641.28341.2836.44727.7631.285 -2.5522.535.83343.56543.5657.73230.3150.781 -1.422336.10344.61744.6178.51431.7370.384 -0.2693.535.87644.77444.7748.89832.0060.086 0.043435.31144.29
11、544.2958.98431.963-0.131 0.9394.534.52743.38043.3808.85331.024-0.283 0.763533.60742.17742.1778.57030.261-0.385 0.9235.532.61540.79940.7998.18429.337-0.450 1.007631.59439.32939.3297.73528.330-0.485 1.0366.530.57737.82637.8267.24927.295-0.500 1.720729.58536.33436.3346.74925.575-0.500 1.0347.528.63234.
12、88234.8826.25024.541-0.488 0.977827.72933.49033.4905.76123.563-0.470 0.9098.526.88032.17132.1715.29122.654-0.446 0.834926.08830.93330.9334.84521.820-0.420 0.7569.525.35329.77829.7784.42521.064-0.393 -1.0121024.67628.70828.7084.03222.075-0.364 0.52210.524.05327.72127.7213.66821.554-0.337 0.4481123.48
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