可变荷载计算.docx

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1、可变荷载计算1）可变荷载横向分布系数计算：荷载对称布置时用杠杆法，非对称布置时用偏心受压法。a.单车列,对称布置（图3-3）时：90 I 902号梁3号梁4号梁图3-3单列车分布系数q =%=o小r4 = 0.4300 = 0.215023=- (0.5700 + 0.5700) = 0.5700b.双车列，对称布置(图3-4)时：180130180图34双列车分布系数7 =z75=10.1667 = 0.0834小=- (0.8333 + 0.3095) = 0.57143=- (0.6905 + 0.6905) = 0.69052c.三列车，对称布置(图3-5)时：180130180130

2、180图3-5三列车分布系数77, =5 =-(0.9048 + 0.0476) = 0.476222 =4 = - (0.0952 + 0.9524 + 0.4286) = 0.7318273=- (0.5714 + 0.0200 5714) = 0.5714d.单列车，非对称布置(图3-6)时：(3-1)由公式:已知： =5, e = 3.35, tz2 = (22.1)2 + 2.12 + 0(-2.1)2 + (-22.1)2 = 44.1,则:1 3.354.21 =11 544.11 3.35x2.17)二 -544.11 3.3507 =- +=3 544.10.5191=0.3

3、5950.20001801801801 3.35 2.1 cczlcu77d = 0.0405544.11 3.35x4.2. = -0.1190544.1图36非对称布置加载e双列车，非对称布置（图36）时:己知: =5, e = 1.80, a2 =(22.1)2 + 2.12 + 0+(-2.1)2 + (-22.1)2 = 44.1,则:1 1.804.2 71 =- += 0.3714,544.11 L802.177)= I-544.11 1.8007 =- +=544.11 1.802.1“F-1 1.80x4.25 =544.1=0.28570.2000= 0J1430.0286

4、f.三列车，非对称布置（图3-6）时:已知: =5, e = 0.25, Yjc=(22. 1)2 + 2.12 + 0+(-2.1)2 + (-22.1)2 = 44.1,则:1 0.2542771 =11 544.11 0.25x2.1% = 544.11 0.250544.11 0.252.14 =544.11 0.254.2,=5 544.1= 0.22380.21190.2000= 0.18810.1762图3-7可变荷载影响线（单位：m）2）按顺桥向可变荷载移动状况，求得支座可变荷载反力的最大值（图3-7）。大路II级28.90 2x7.8752+ 214.2 = 441.79kN

5、双孔布载单列车时:双孔布载双列车时:2B = 2441.79 = 883.58kN双孔布载三列车时:3B = 3441.79 = 1325.37kN单孔布载单列车时:B = 28:)875 + 214.2 = 327.99kN单孔布载双列车时:单孔布载三列车时:2B = 2 327.99 = 655.98kN36 = 3 x 327.99 = 983.97kN3）可变荷载横向分布后各梁支点反力（计算的一般公式为 =小/）见表3-3。表3-3各梁支点反力计算荷载横向分布状况大路II级荷载/kN计算方法荷载布置横向分布系数单孔双孔BBR1对称布置按杠杆法计算单列车大路II级小0327.990441

6、.790%0.215070.5294.985fh0.5700186.95251.82Z0.215070.5294.985%000327.99441.79双列车大路-级小0.0834655.9854.71883.5873.691%0.5714374.83504.88%0.6905452.95610.11%0.5714374.83504.88%0.083454.7173.6911312.031767.25三列车大路级小0.4762983.97468.571325.37631.14jh0.7318720.07969.91%0.5714562.24757.3240.7318720.07969.91%0

7、.4762468.57631.142939.513959.41非对称布置按偏心压力法计算单列车大路-级小0.5191327.99170.26441.79229.33%0.3595117.91158.82%0.200065.6088.358%0.040513.2817.892jls-0.1190-39.03-52.57328.02441.83双列车大路级小0.3714655.98243.63883.58328.16%0.2857187.41252.44%0.2000131.2176.7240.114374.98100.990.028618.7625.27655.98883.58三列车大路-级小0

8、.2238983.97220.211325.37296.62%0.2119208.5280.85%0.2000196.79265.07Z0.1881185.08249.3%0.1762173.38233.53983.971325.374）各梁永久荷载，可变荷载反力组合：计算见表3-4,表中均取用各梁的最大值，其中冲击系数为：1 + / = 1.2473影响长度按双孔计，即为L = 2x28.90 = 57.8m,且表中汽车荷载项已计入冲击系数值。表3-4各梁永久荷载、可变荷载基本组合计算表（单位：/kN）各梁反力与R,与恒载955.041025.661025.661025.66955.044987.07大路-II级对称荷载787.221209.76944.601209.76787.224938.57大路-II级非对称荷载409.32350.30330.63310.95291.281692.48恒载十大路对称布载1709.602200.381935.222200.381709.609755.19恒载+大路非对称1331.701340.921321.251301.571213.666509.10