公路-I级车道荷载的均布先荷载标准值qk和集中荷载标准值Pk为:
qk = 10.5 kN/m 计算弯矩是,集中荷载为:
Pk = 237.20 kN 计算剪力时,集中荷载为:
Pk = 284.64 kN
按《桥规》车道荷载的均布荷载应满布于使结构产生最不利效应的同号影响线上,集中荷载标准值只作用于相应影响线中一个最大影响线峰值处。多车道桥梁上还应考虑多车道折减,双车道折减系数ξ=0.67,但不小于两设计车道的荷载效应。
3.2.1 汽车荷载横向分布系数计算
空心板跨中和l/4处的荷载横向分布系数按铰接板法计算,支点处按杠杆原理法计算。支点至l/4点之间的荷载横向分布系数按直线内插求得。
(1)跨中及l/4处的荷载横向分布系数计算 首先计算空心板的刚度参数γ:
?? 由前面计算:
I = 1.03?1011 mm4
?2EIbIb()2?5.8()2 4GITlITlI = 1.09?1011 mm2 b = 1404 mm
l = 24600 mm
将以上数据代入,得:
1.03101114042()?0.01242 ??5.8111.091024600 求得刚度参数后,即可按其查《公路桥涵设计手册——梁桥(上册)》(徐光辉,胡明义,主编,人民交通出版社,1996年3月)第一篇附录(二)中10
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块板的铰接板桥荷载横向分布影响线表,由γ=0.01及γ=0.02内插得到γ=0.010242时,1~5号板在车道荷载作用下的荷载横向分布影响线值,内插计算结果见表 1-2中。每个对应的板号,各块板竖向影响线之和等于1,用此来进行校核。
表 1-2
板号1γ0.010.020.0102420.010.020.0102420.010.020.0102420.010.020.0102420.010.020.010242234510.1810.2340.1822830.1580.1920.1588230.1310.1160.1306370.110.1110.1100240.0930.0850.09280620.1580.1920.1588230.1540.1880.1548230.1370.1570.1374840.1140.120.1141450.0970.0920.09687930.1310.1460.1313630.1370.1570.1374840.1370.1620.1376050.1230.1380.1233630.1040.1060.104048各板横向分布影响线坐标值计算表45670.110.0930.080.070.1110.0850.0660.0520.1100240.0928060.0796610.0695640.1110.0970.0830.0730.120.0920.0710.0560.1112180.0968790.082710.0725890.1230.1040.090.0780.1380.1060.0820.0650.1233630.1040480.0898060.0776850.1270.1160.10.0870.1480.1290.1010.080.1275080.1163150.1000240.0868310.1160.1230.1140.10.1290.1420.1260.1010.1163150.123460.114290.10002480.0630.0430.0625160.0650.0460.064540.070.0510.069540.0780.0650.0776850.090.0820.08980690.0580.0370.0574920.060.040.0595160.0650.0460.064540.0730.0560.0725890.0830.0710.08271100.0560.0340.0554680.0580.0370.0574920.0630.0430.0625160.070.0520.0695640.080.0660.079661 各板的荷载横向分布影响线及横向最不利荷载布置如图1-4所示。
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0.0930.1100.1310.1590.182500.1110.1320.1580.17850505050140.4
各板的荷载横向分布系数计算见表1-3,计算公式为:
0.0941800.1180.1370.1471800.1461801801800.1001300.1250.1320.1271300.1231301301300.1091800.1230.1150.1050.1031801801801800.1191300.1110.0990.0920.089130130130130 - 8 -
0.1201800.0920.0830.0771801801800.0741800.1061300.0820.0740.0691301301300.0661300.0951800.0740.0660.0700.0631801801801800.0840.0610.0580.0790.0570.055
mq?1?ηiq 2式中 ηiq——表示车轮对应的影响线坐标值。 1号板: 四行汽车:
11η??i汽2(0.178?0.146?0.123?0.103?0.089?0.074?0.066?0.058) 2 ?0.4185m4汽? 两行汽车:
m2汽?2号板:
11η??i汽2(0.178?0.146?0.123?0.103)?0.275 2四行汽车:
m4汽?11η?(0.158?0.147?0.127?0.105?0.092?0.077?0.069?0,061)?i汽 22 ?0.344511η?(0.158?0.147?0.127?0.105)?0.275 ?i汽22两行汽车:
m2汽?3号板:
四行汽车:
m4汽?11η??i汽2(0.132?0.137?0.132?0.115?0.099?0.083?0.074?0.066) 2 ?0.41911η??i汽2(0.132?0.137?0.132?0.115)?0.258 2两行汽车:
m2汽?4号板:
四行汽车:
m4汽?11η?(0.111?0.118?0.125?0.123?0.111?0.092?0.082?0.074)?i汽 22 ?0.41811ηi汽?(0.111?0.118?0.125?0.123)?0.2385 ?22两行汽车:
m2汽? - 9 -