. . . .
RaRb? ab5?220?92x92?(27.975?x)?80?(24.245?x) ?22.3852.22解得x=8.588m
故桥上活载总重=5?220?27.975?92?(24.245?8.588)?80?6300.34KN 在主力作用下的力已计入冲击系数，制动力按静活载的7%计算： 制动力
T??0.07?441.0238KNE2E4制动力作用附加内力Nt?T?2?220.512KN 其下弦杆内力见表2,12 端斜杆制动力计算
E0E1杆力影响线顶点位置离左端点支点7.46m，设将列车荷载的第 4 轴重 Pl置于影响线顶点处。因为影响线为三角形，故根据结构力学所述的法则，若满足下列条件，则该活载位置是产生最大杆力时的荷载
p1?Ra2.7975?220?0.9325?220R??110?b?84.7a7.46b
Rap1?Rb?0.375?220?87.96??87.8ab将第 3 轴重或第 5 放到顶点位置上均不满足上述条件，故将上述活载即为产生最大杆力时的活载。
T?7(4.6625?220?92?27.975?80?36.3675?455.6195KN 100制动力所产生的杆件力Nt和M2： 轴向力Nt?.下载可编辑.
T455.6195??227.81KN 22. . . .
下弦杆弯矩
M1?0.4T/2*h?227.81?0.37?0.4?33.72KN.m端斜杆弯矩M2?0.7M?59.00KN.m
第四节 疲劳力计算
1.疲劳轴力
疲劳荷载组合包括设计载荷中的恒载和活载(包括冲击力、离心力，但不考虑活载发展系数)。列车竖向活载包括竖向动力作用时，应将列车竖向静活载乘以运营动力系数(1+μf)。同时，第 4.3.5 条又规定，焊接及非焊接(栓接)构件及连接均需进行疲劳强度检算，当疲劳应力均为压应力时，可不检算疲劳。 疲劳计算采用动力运营系数
18?1.157
40?74.618吊杆：1??f?1??0.32775
40?14.92弦，斜杆：1??f?1?E2E4:Nnmax?Np?(1??f)Nk?1025.46?1.157?2586.44?4017.97Nnmin?Np?1025.46KN
其余计算力见表2-1。 2 吊杆疲劳弯矩
作用在纵梁上的恒载p=9.73KN|m
由恒载产生纵梁对横梁的作用力Np=72.5858KN 当L=14.92m和a=0.5时，k=60.988KN\\m
由活载产生纵梁对横梁的作用力Nk?k???60.988?7.46?454.97KN
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B?c5.75?2)?72.5858?()?136.098KN.m 22B?c5.75?2由静活载产生的简支梁弯矩Mk?Nk()?454.97?()?853.07KN.m
22由恒载产生的简支梁弯矩Mp?Np(冲击系数1???1.51
横梁??Np72.58581??0.1057,??1?(0.3247?0.1057)?1.0365Nk(1??)454.97?1.516
3ui(2?0.5?)b?3is3ui(2?0.5?)b?3is横梁Mpk?Mp??（1??）Mk?136.098?1.0365?1.51?853.07?1471.25KN/mMBp?MpMBpk?Mpka?c187.5?200??0.6739B575L503.1??1??0.5234L961.25ib?1136.06Ecm,is?66.19Ecmu?MBp?3(2?0.5?0.5234)?MBp?31136.06E(2?0.5?0.5234)??366.19E1136.06E?366.19E?0.6739?136.098?8.380KN.m
?0.6739?1417.25?87.26KN.m 第五节 主桁杆件力组合 1主力组合
NI?Np??(1??)Nk?Ns,例如A1A3：NI??781.2?2506.59?31.624??3319.414E4A5:NI??82.98?872.95??955.93KN,N?603.11KN1I
2主力和附加力组合
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以A1A3,E2E4为例A1A3：主力N1??3319.141KN，附加风力Nw??123.34KN主力?横向附加力Nii??3319.141?123.34??3442.48KNN11?3442.48N1????2868.734??3319.141KN（绝对值取大，故主力控制设计）。111.21.2 E2E4：主力N1?4541.37KN，附加风力Nw?535.659KN主力?横向附加力Nii?4541.37?535.659?5077.029KNN115077.029N1???4230.8575?4541.37KN（主力控制）111.21.2主力?纵向附加力（制动力）Niii?4541.37?220.08?4761.45KNN111?N114761.45??3809.16?4541,37KN（主力控制）1.251.25
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表 2.1 主桁杆件力计算
影响线杆件名称加载顶点总面面积Ω长度l位α积ΣΩ单位项次m12m3m4NpkNk=kΩ1+μ(1+μ)Nkaamax-aηη(1+μ)NkNS恒载活载摇摆力附加力内力组合仅有轴力杆件疲劳计算内力吊杆下端弯矩MBkN?m26kN5kN/m6kN78kN9100.31230.32130.30300.31870.32470.30300.2926110.01240.00340.02170.00600.00000.02170.032112kN13kN14N=max{主+风主+风主+制主+制C主力桥门架Nn=Np+(1平纵联风制动力N=N+(1风力NII=NI+弯矩NIII=NI+弯矩NI,NII/1.1+μfIp力NWNT+μf)NkNW'MIII2,NIII/1.2+μ)Nk+NSNW(NW')MIINT5}kNkNkNkNkNkN?mkNkN?mkNkN15-123.34-199.24300.21535.66582.75-108.6963.94224.98220.08214.481617181920212223-3319.41-4872.542284.9833.724761.455515.7859.002578.24-149.851.161.162433.39534.36-1865.93-264.001344.90-62.11-867.42438.28739.424541.375301.301.161.161.161791.454025.734726.352425上A1A374.600.200-43.40-43.40-781.2046.33弦杆A3A574.600.400-65.11-65.11-1171.9845.03E0E274.600.10024.4124.41439.38下弦E2E474.600.30056.9756.971025.46杆E4E4'74.600.50067.8267.821220.76E0A174.600.100-41.51-41.51-747.1866.31A1E28.2958.02斜杆E2A316.5849.73A3E424.8741.44E4A533.16竖杆EiAi14.920.5000.1008.207.467.46134.280.100-4.61-12.81-4.61-82.9854.8060.990.1002.0518.4513.84249.1258.2052.790.100-0.51-25.11-23.06-415.0863.5351.2032.8032.29581.2279.2249.8147.7545.4044.5647.7548.68-2010.721.244-2501.34-2931.901.244-3647.281165.581.2441449.982586.441.2443217.533022.061.2443759.44-1982.101.244-2465.731596.701.244-40.40-1250.731.244130.24944.641.244-268.30-676.241.244449.36454.991.510559.00687.03-333.77-841.24162.021175.13-50.26-1555.911986.291.0021-2506.59-31.621.0006-3649.47-51.091.00361455.20165.421.00103220.75295.161.00003759.44321.101.0036-2474.611.00541997.02-149.85-3319.41-3442.75-4872.54-5071.772060.004541.375301.302424.145077.035884.05-3221.79-3330.48131.492578.24-149.85-1986.08239.971446.34-393.35-955.93603.11836.15-11.564311.88902.98150.2668-2.56190.2120-0.74640.0986-0.14840.19540.05792.88660.11271.07110.22610.47310.12931.0097-1571.001.4811239.97-1986.081.16239.971446.34-393.35-955.93603.11836.151.161.161.161.161.161.331.01881197.221.17851.03771.07891.0216-393.35-872.95603.11701.878.38,87.26 .下载可编辑.
74.6M单线铁路下承式栓焊简支钢桁梁桥设计说明
