新澆混凝土模板側壓力的計算研究一、實驗數(shù)據(jù)表1.實驗測的澆筑速度與最大壓力編號澆筑速度V(m/h)實測值P(kN/m)編號澆筑速度V(m/h)實測值P(kN/m)10.2211.68232.9246.7320.2514.60242.9257.4630.1728.84253.1153.8940.3818.98263.2458.7850.4720.08273.4345.6360.4338.33283.7344.5470.6344.98293.9944.5480.7825.19314.6557.6890.8730.30324.6761.33100.8337.75334.7962.57111.0541.62344.9772.29121.2447.83355.6265.57131.5134.32365.9575.06141.7849.873714.1079.14151.9545.273810.0071.14162.0040.303915.7074.79172.1045.85403.2938.00182.1252.214115.8180.80192.2457.32424.1352.00202.3352.574315.0062.50212.4656.59222.7050.75數(shù)據(jù)編號1至36為之前規(guī)范給出的圖中已測的的數(shù)據(jù)，其中考慮到如今泵送混凝土的坍落度普遍偏高，按照規(guī)范中坍落度的修正我們在實測值上乘以了1.15。溫度與混凝土側壓力的關系，采用線性比例關系圖。通過以上修正，表中的實測值實際上是經(jīng)過修正，換算成溫度200C，坍落度12~16cm下的模板側壓力值。二、實驗數(shù)據(jù)分析依舊采用冪函數(shù)的關系即來描述側壓力同澆筑速度的關系，對表中的測試數(shù)據(jù)采用最小二乘法進行回歸分析可以得到：(1)圖1.澆筑速度對最大側壓力的影響復相關系數(shù)說明該方程能較好的反映混凝土的澆筑速度和最大側壓力之間的關系。對兩變量取對數(shù)，線性擬合后進行統(tǒng)計檢驗，即得到：y=0.3309x+1.5404（2）圖2.取對數(shù)后澆筑速度對最大側壓力的影響分析顯示，線性方程的復相關系數(shù)為，F(xiàn)統(tǒng)計值為118.18遠大于顯著水平為0.05（即保證率95%）的F臨界值4.06，說明側壓力與澆筑速度取對數(shù)方程后的線性關系顯著，同時t統(tǒng)計量為10.871大于顯著水平為0.05的t臨界值2.02，即反映lg（V）與lg（P）的增加值影響顯著?？紤]最大偏差，對方程（2）進行修正，即y=0.3309x+1.5404+0.256=0.3309x+1.7964此時則有三、最大側壓力公式推導當澆筑高度比較高時，澆筑時間比較長，施工時可能需要分層，雖然混凝土未達到初凝，但是由于模板尺寸，配筋，混凝土本身的物理性質(zhì)施工方法等都有可能影響有效壓頭，所以引入來考慮各種因素的影響即：（3）取混凝土重度為24，實驗數(shù)據(jù)的混凝土溫度均以規(guī)格化到,按現(xiàn)行規(guī)范公式，聯(lián)合方程（1）和方程（3）即可得：為了計算方便和安全可靠，同時考慮坍落度影響系數(shù)將上式簡化為：（4）坍落度在6~9cm時取0.85，坍落度在14~18cm時取1.0同時計算得到的P 值不能超過。該公式與其他規(guī)范公式進行比較，見表2：四、結論通過對比分析，得出以下結論：美國ACI公式適用于澆筑速度較慢（澆筑速度約在2m/h以下）的模板側壓力計算，當超過時公式計算值極具增長，超過rH。同時ACI中規(guī)定模板側壓力最小值不能小于30kN/m。蘇聯(lián)模板側壓力計算值普遍偏小。德國公式在澆筑速度較慢時偏小，在澆筑速度達到4~6m/h時能夠較好的吻合并且有一定的安全儲備。冶金院的公式計算值雖能較好的吻合并涵蓋住實驗測的值，但是誤差普遍偏大，本文推薦公式在整個曲線段上能夠較好的擬合實驗值，并且有一定的安全儲備。表2.各國規(guī)范側壓力計算值對比編號澆筑速度實測值推薦公式我國GB50204-92美國ACI(kN/m2)蘇聯(lián)德國DIN18218冶金院V(m/h)(kN/m2)(kN/m2)(kN/m2)柱子墻體(kN/m2)(kN/m2)(kN/m2)10.2211.6840.4819.6214.1747.06V<0.5m/h時,P=rH20.9030.1220.2514.6041.8620.9814.9747.3121.3431.1630.1728.8437.7017.0212.8046.6320.1328.0540.3818.9846.3325.7018.1348.2923.1034.4850.4720.0848.8228.5420.3548.9824.3336.3360.4338.3347.7127.2619.3248.6623.7635.5170.6344.9852.6433.1824.4650.2623.2926.6239.1780.7825.1955.4936.8728.1851.4124.2828.6941.3090.8730.3057.0038.9030.4052.1024.8629.9242.42100.8337.7556.3738.0429.4551.8124.6129.3941.95111.0541.6259.6642.6234.7553.4526.0232.3444.40121.2447.8362.2146.3339.4954.9327.2834.9846.29131.5134.3265.3551.1346.2257.0229.0638.7248.63141.7849.8768.0955.5252.9459.1130.8442.4650.67151.9545.2769.6558.0857.1460.4131.9644.7951.83162.0040.3070.1358.8858.4860.8332.3145.5452.19172.1045.8570.9560.2760.8561.5732.9446.8652.80182.1252.2171.1460.5961.4161.7433.0947.1752.94192.2457.3272.1362.2964.4162.6733.8948.8453.68202.3352.5772.8863.6066.7963.4134.5250.1654.24212.4656.5973.8665.3169.9564.4035.3651.9254.96222.7050.7575.5868.4075.8966.2436.9355.2256.25232.9246.7377.0971.1681.4267.9638.4058.3057.37242.9257.4677.0971.1681.4267.9638.4058.3057.37253.1153.8978.3273.4486.1769.4439.6660.9458.28263.2458.7879.1575.0089.4970.4740.5462.7958.90273.4345.6380.2577.1094.0871.9041.7665.3459.72283.7344.5481.9580.42101.6074.2343.7569.5260.99293.9944.5483.3583.17108.0976.2545.4773.1362.03314.6557.6886.6089.79124.54V>4.5m/h規(guī)范中未給出49.8382.2864.45324.6761.3386.6789.95124.9449.9482.5064.50334.7962.5787.2691.16128.1050.7884.2664.94344.9772.2988.0492.81132.4551.9386.6865.52355.6265.5790.7998.70148.6756.2395.7067.57365.9575.0692.10101.56156.9058.42100.2868.54373.2938.0079.4275.5290.6340.8463.4259.10384.1352.0084.0784.62111.5646.3975.0662.563914.1079.14114.27V>6m/h規(guī)范中未給出360.02112.29213.2585.044010.