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'桥梁的下部结构毕业设计2支座的设计2.1板式橡胶支座的选用板式橡胶支座由多层橡胶片与薄钢板镶嵌、粘合压制而成。有足够的竖向刚度以承受垂直荷载,能将上部构造的反力可靠地传递给墩台;有良好的弹性,以适应梁端的转动;又有较大的剪切变形,以满足上部构造的水平位移。板式橡胶支座与原用的钢支座相比,有构造简单,安装方便;节约钢材,价格低廉,养护简便,易于更换等优点;且建筑高度低,对桥梁设计与降低造价有益;有良好的隔震作用,可减少活载与地震力对建筑物的冲击作用。因此本设计选用板式橡胶支座。采用天然橡胶,适用温度为-40℃~60℃(环境温度-23℃~37.4℃),硬度取60。2.2计算支座反力根据上部结构计算结果,梁体自身构造产生的支座反力标准值为,,其结构自重引起的支座反力标准值为,公路-Ⅰ级荷载引起的支座反力标准值为229.15kN,人群荷载标准值57.13kN,公路-Ⅰ级和人群荷载作用下产生的跨中挠度为;根据当地的气象资料,主梁的计算温差。2.3支座平面尺寸的确定所需支座面积:(2-1)于主梁底板宽为1.6m,故初步选定板式橡胶支座的平面尺寸为:a=600mm(顺桥向),b=700mm,,故采用中间层橡胶片厚度t=15mm。83
2.3.1计算支座的平面形状系数S,并且(2-2)2.3.2计算橡胶支座的抗压弹性模量(2-3)式中:为常温下支座抗剪弹性模量,取。2.3.3验算橡胶支座的承压强度,满足规范要求。(2-4)式中:为橡胶支座使用阶段的平均压应力限值。2.4确定支座的厚度1.假设支座水平放置,且不考虑混凝土收缩和徐变的影响。主梁的计算温差为,温度变形由主梁两端均摊,则每一支座的水平位移为:(2-5)式中:为混凝土的线膨胀系数;为简支梁的计算跨径。2.为了计算汽车荷载制动力引起的水平位移,首先要确定作用在每一支座上的制动力:对于34.02m桥跨,一个设计车道上公路-Ⅰ级车道荷载总重为:,则其制动力标准值为,但按《桥规》,不得小于90kN,故取总制动力为90kN参与计算,5片梁共10个支座,作用于一个支座上的制动力。83
3.确定需要的橡胶片总厚度:不计汽车制动力:(2-6)计入汽车制动力:(2-7)式中:为支座剪变模量,常温下。同时,考虑到橡胶支座的稳定性,《桥规》规定应满足:(a为矩形支座短边尺寸)选用5层橡胶片组成的支座,上下层橡胶片厚8mm,中间层厚15mm,薄钢板厚5mm,则橡胶片总厚度:且小于9cm(合格)4.支座总厚:2.5支座偏转情况的验算1.由下式计算支座的平均压缩变形:(2-8)式中:为橡胶体积模量,。按《桥规》规定,满足,即,合格。2.计算梁端转角:由关系式和可得:(2-9)设结构自重作用下,主梁处于水平状态。已知公路-Ⅰ级荷载作用下的跨中挠度,代入上式得:3.验算偏转情况:83
即,验算合格,支座不会落空。2.6验算支座的抗滑稳定性1.计算温度变化引起的水平力:(2-10)2.为了保证橡胶支座与梁底或与墩底顶面间不发生相对滑动,则应满足以下条件1)则(合格)2)(合格)结果表明,支座不会发生相对滑动。由以上分析,本设计选用的支座型号为GJZ600×700×81。3桥墩构造设计3.1桥墩类型和主要材料桥墩选用钻孔灌注桩双柱式桥墩。主要材料:混凝土采用C35混凝土;主筋采用HRB400钢筋;钢筋混凝土容重取。强度标准值:轴心抗压:,轴心抗拉:强度设计值:轴心抗压:,轴心抗拉:混凝土的弹性模量:3.2桥墩截面尺寸拟定根据沈阳至阜新公路桥的设计资料,参照《公路桥涵设计手册—墩台与基础》中的83
计算实例以及按照有关的规定,先初步拟定桥梁桥墩的尺寸,如图3-1所示,然后进行配筋设计和验算,如不符合要求,进行必要的修改。图3-1桥墩一般构造/cmFig3-1Piergeneralstructure/cm将墩柱的圆形截面换算为0.8倍的方形截面时,a=0.8d=0.8×150=120cm,故由于盖梁的跨高比,故可按一般构件进行相关计算和验算;盖梁的悬臂端,也属于一般的钢筋混凝土悬臂梁。3.3盖梁计算盖梁截面尺寸见图3-2。83
图3-2盖梁尺寸/cmFig3-2Thesizeofbentcap/cm3.3.1垂直荷载计算1)盖梁自重及内力计算(表3-1)2)活载计算(1)活载横向分配:荷载对称布置用杠杆法,非对称布置用铰接板法。表3-1盖梁自重及内力表Table3-1Thedead-weightandinternalforceofbentcap截面编号自重/KN弯矩/KNm剪力/KN左右1-10.5×(0.7+1.0259)×1.05×2.4×25=54.366-54.366×0.492=-26.748-54.366-54.3662-20.5×(1.0259+1.6)×1.85×2.4×25=1453.74-54.366×2.342-145.74×0.856=-252.079-200.106-200.1063-31.15×1.6×2.4×25=110.4-54.366×3.492-145.74×2.006-110.4×0.5×1.15=-545.681-310.5064564-40.1×1.6-54.366×3.592-145.74×2.106446.4446.483
×2.4×25=9.6-110.4×0.675+9.36×0.05=-576.2515-53.1×1.6×2.4×25=297.6-54.366×6.692-145.74×5.206-110.4×3.775+9.63.15+297.6×1.55=-1047.780148.8148.86-61.55×1.6×2.4×25=148.8-54.366×8.242-145.74×6.756-110.4×5.325+9.6×4.7+297.6×3.1+148.8×0.775=-937.58400注:,钢筋混凝土容重取。a.单列公路-I级荷载对称布置:图3-3单列公路-I级荷载对称布置Fig3-3singlerowroad-Ilevelofloadsymmetricalarrangementb.双列公路-I级荷载对称布置:图3-4双列公路-I级荷载对称布置Fig3-4tworowroad-Ilevelofloadsymmetricalarrangement83
c.三列公路-I级荷载对称布置:图3-5三列公路-I级荷载对称布置Fig3-5threerowroad-Ilevelofloadsymmetricalarrangementd.四列公路-I级荷载对称布置:图3-6四列公路-I级荷载对称布置Fig3-6Fourrowroad-Ilevelofloadasymmetricalarrangemente.五列公路-I级荷载对称布置:83
图3-7五列公路-I级荷载对称布置Fig3-7fiverowroad-Ilevelofloadasymmetricalarrangementf.公路-I级荷载非对称布置:图3-8公路-I级荷载非对称布置Fig3-8road-Ilevelofloadsymmetricalarrangement①单列公路-Ⅰ级荷载非对称布置83
②双列公路-Ⅰ级荷载非对称布置③三列公路-Ⅰ级荷载非对称布置④四列公路-Ⅰ级荷载非对称布置83
⑤五列公路-Ⅰ级荷载非对称布置(2)公路-I级荷载顺桥行驶:;a.单孔单列公路-I级荷载,图3-9公路-I级荷载单孔单列布置Fig3-9Road-Ilevelofloadsingle-holeandsinglerowarrangement83
b.双孔单列公路-I级荷载图3-10公路-I级荷载双孔单列布置Fig3-10Road-Ilevelofloadtwo-holeandsinglerowarrangement(3)活载横向分配后各梁支点反力:计算式为:计算结果见表3-2。表3-2-1各梁活载反力计算表Table3-2-1Calculationofanti-beamliveload荷载横向分布情况公路-Ⅰ级荷载计算方法荷载布置横向分布系数单孔双孔B/KN/KNB/KN/KN对称布置按杠杆原理计算单列行车0491.06701228.96700000.5245.534641.4840.5245.534641.484000000双列行车0491.06701228.96700.355174.329436.2830.855419.8621050.7670.855419.8621050.7670.355174.329436.28300083
三列行车0491.06701228.96700.5245.534614.4841491.0671228.9671491.0671228.96705245.534614.484000四列行车0.145491.06771.2051228.967178.2000.855419.8621050.7671491.0671228.9671491.0671228.9670.855419.8621050.7670.14571.205178.200五列行车0.5491.067245.5341228.967614.4841491.0671228.9671491.0671228.9671491.0671228.9671491.0671228.9670.5245.534614.484表3-2-2各梁活载反力计算表Table3-2-2Calculationofanti-beamliveload荷载横向分布情况公路-Ⅰ级荷载计算方法荷载布置横向分布系数单孔双孔B/KN/KNB/KN/KN非对称布置按铰接板法原理计算单列行车0.2861491.067140.4941228.967351.6070.2426119.133298.1470.177387.066217.8960.125361.531153.9900.094246.259115.7690.080539.53198.932双列行车0.4932491.067242.1941228.967606.1270.4630227.364569.0120.3868189.945475.3640.2852140.052350.5010.2139105.039262.8760.184190.405226.25383
三列行车0.6343491.067311.4841228.967779.5340.6302309.470779.4110.5937291.546729.6380.4921241.654604.7750.3810187.097468.2360.3225158.369396.342四列行车0.7353491.067361.0821228.967903.6590.7499368.251921.6020.7536370.068926.1500.7016344.533862.2430.6014295.328729.1010.5296260.069650.861五列行车0.8158491.067400.6141228.9671002.5910.8441414.5101037.3710.8789431.5991080.1390.8796431.9431080.1390.8366410.8271028.1540.7993392.510982.313(4)恒载与活载反力汇总恒载与活载反力汇总见表3-3。冲击系数1+μ=1.1724(同上部结构)表3-3各梁反力汇总表Table3-3Thesummaryofanti-beamforce荷载情况1号梁2号梁3号梁4号梁5号梁6号梁/KN/KN/KN/KN/KN/KN上部恒载867.84783.31894.73894.73783.31867.84公路-I级(双孔五列对称布置)×(1+μ)720.4211440.8411440.8411440.8411440.841720.421公路-I级(双孔五列非对称布置)×(1+μ)1175.4381216.2141266.3551267.3631206.4081151.66483
3.3.2双柱反力计算图3-11双柱反力计算图/cmTable3-11ReactionsactingofdoublePier/cm计算式为:(3-1)即表3-4墩柱反力计算表Table3-4Calculationofpierreaction荷载情况上部恒载公路-Ⅰ级(双列五孔对称布置)公路-Ⅰ级(双列五孔非对称布置)2545.883602.1033665.742545.883602.1033603.2283.3.3盖梁各截面内力计算1)弯矩计算83
图3-12盖梁各截面内力计算图/cmTable3-12Interalforcesofcopinginsectionsonbentcap/cm其盖梁各截面弯矩值见表3-5。表3-5弯矩计算表Table3-5Thecalculationofmoments墩柱反力梁的反力各截面弯矩83
荷载情况/KN/KN/KN/KN1-12-23-34-45-56-6上部恒载2545.88867.84783.31894.730-1605.504-2603.52-2603.52337.947337.947公路-Ⅰ级对称荷载3602.103720.4211440.8141440.8140-1332.779-2161.263-1873.0952593.5122593.512公路-Ⅰ级非对称荷载3665.741175.4381216.2141266.3550-2174.56-3526.314-3217.284672.389684.3752)相应于最大弯矩值时的剪力计算见表3-6。一般计算公式:1-1截面:,;2-2截面:;3-3截面:,;4-4截面:,;5-5截面:,;6-6截面:。表3-6剪力计算表/KNTable3-6Thecalculationofshearforces/KN83
荷载情况上部荷载公路-Ⅰ级对称布置公路-Ⅰ级非对称布置墩柱反力2545.883602.1033665.74梁的反力/KN867.84720.4211175.438/KN783.311440.8411216.214/KN894.731440.8411266.355各截面剪力1-1/KN000/KN-867.84-720.421-1175.4382-2/KN-867.84-720.421-1175.438/KN-867.84-720.421-1175.4383-3/KN-867.84-720.421-1175.438/KN1678.042881.6822490.3024-4/KN1678.042881.6822490.302/KN894.7301440.8411274.0885-5/KN894.7301440.8411274.088/KN007.7336-6/KN007.733/KN007.7333)截面内力组合(1)弯矩组合见表3-7。其中活载按最不利情况考虑。表3-7弯矩组合表Table3-7Combinationofmoments截面号内力组合值1-12-23-34-45-56-61上部荷载0-1605.504-2603.52-2435.716337.947337.9472盖梁自重-26.748-252.079545.681-576.251-1047.780-937.58483
3公路-Ⅰ荷载对称布置0-1332.779-2161.263-1873.0952593.5122593.5124公路-Ⅰ荷载非对称布置0-2174.56-3526.314-3277.284672.389684.37551+2+3-32.098-4094.990-6804.809-6236.6932779.1172911035261+2+4-32.098-5273.484-8715.881-8202.56589.545238.561(2)剪力组合见表3-8。3.3.4各墩水平力计算采用集成刚度法进行水平力分配。上部构造每片边梁支点反力为867.85×2=1735.7;每片中梁支点反力:1号梁反力为783.31×2=1566.62KN;2号梁反力为894.73×2=1789.46KN。中墩橡胶支座中钢板总厚度20mm,剪切模量,每跨梁一端设有6个支座,每个支座的抗推刚度为:(3-2)表3-8剪力组合表Table3-8Combinationofshearforces截面号剪力组合值1-12-23-34-45-56-61上部荷载/KN0-867.84-867.841478.04894.730/KN-867.84-867.841478.04894.73002盖梁自重/KN-54.366-200.106-310.506446.4148.80/KN-54.366-200.106456446.4148.8083
3公路-Ⅰ级荷载对称布置/KN0-720.421-720.4212881.6821440.8410/KN-720.421-720.4212881.6821440.841004公路-Ⅰ级荷载对称布置/KN0-1175.438-1175.4381440.8411274.0887.733/KN-1175.438-1175.4382490.3022490.3027.7337.73351+2+3/KN-65.239-2290.125-2422.6051274.0883269.41310.826/KN-2115.438-2290.1256355.2033626.533178.5610.82661+2+4/KN-65.239-2927.148-3059.6286333.7473035.9590/KN-2752.260-2927.1485807.2713393.079189.3860每个墩上设有两排橡胶支座,则支座刚度为取桥台及两联间桥墩的橡胶支座的摩擦系数,其中最小摩擦系数。1)桥墩(台)刚度计算桥墩(台)采用C35混凝土,其弹性模量(1)各墩(台)悬臂刚度计算如下一墩两柱:,(3-3),图3-13悬臂刚度计算图示Table3-13Cantileverstiffnesscalculatesgraphicalrepresentation83
对于桥台:向河方向:;向岸方向:台背填硬塑粘性土的地基系数及容重分别为:,,(2)墩(台)与支座串连,串联后各刚度为:对桥墩:对桥台:向河方向:向岸方向:2)制动力的分配(1)制动力计算公路-I级荷载布置如图3-14。制动力按车道荷载进行计算。图3-14公路-I级荷载布置/mFig3-14Road-Ilevelofloadarrange/m单列行车产生的制动力:双孔布载时:83
单孔布载时:由于《桥规》的规定,不得小于,故取。(2)制动力分配(3-4)则各墩台分配的制动力为:(向河方向)(向岸方向)(3)号及5号台的最小摩阻力,其中则:。因大于0号台和,两台处支座均无滑移的可能性,故制动力不再进行重分配。(4)桥台板式橡胶支座的水平力取摩檫系数,则板式橡胶支座产生的摩阻力,大于0号台和,故取,3)温度影响力的分配(温度上升20℃)(1)对一联中间各墩设板式橡胶支座的情况a.求温度变化临界点距0号台的距离(3-5)则b.计算各墩温度影响力:(3-6)式中:83
故:临界点以左:临界点以右:0号台及7号台最小摩阻力,大于温度影响力,故温度影响力不必进行重分配。(2)对桥台及两联间桥墩设板式橡胶支座的情况:板式橡胶支座的摩阻力为,大于温度影响力,故0号台为703.153KN,7号台为709.877KN。4)各墩台水平力汇总(表3-9)表3-9各种水平力汇总表Table3-9Thesummaryofhorizontalforces墩(台)号荷载名称012345制动力/KN22.44730.02730.02730.02730.02722.447温度影响力/KN703.153566.526192.469181.589555.647709.877制动力+温度影响力/KN725.6596.553222.496211.616585.674732.804注:0号台和5号台未计台后填土压力,各墩台均未考虑土压力。83
3.3.5盖梁配筋设计盖梁采用C35混凝土,其轴心受压强度为:=16.1MPa。主筋采用HRB400钢筋,取直径d=32mm,其抗拉强度设计值为:=330MPa,一根Φ32钢筋的面积为,钢筋保护层厚度60mm。1)弯矩作用时,各截面配筋设计表3-10-1截面配筋设计Table3-10-1Thedesignsectionofsteelreinforcement截面号/KN·mb/mm/mm/mm1-1-32.0982400965.90.862-2-5273.4842400154091.333-3-8715.88124001540154.194-4-8202.56524001540144.645-52779.1172400154047.436-62911.3522400154049.73注:表中结构重要性系数;对于HRB400级钢筋,,对于表中所述x均小于表3-10-2截面配筋设计Table3-10-2Thedesignsectionofsteelreinforcement截面号所需Φ32钢筋根数实用Φ32钢筋根数ρ%1-1117.090.151080420.352-210693.913.315120630.333-318054.2522.425201050.544-416938.3721.0625201050.545-55553.626.925201050.546-65822.937.225201050.5483
注:①,,故取②结构的重要性系数2)剪力作用时各截面的强度验算(1)计算公式《公路桥规》规定,因本设计的跨高比为,故可按钢筋混凝土一般构件进行计算与验算,且需进行挠度验算。《公路桥规》规定了截面最小尺寸的限制条件,即;《公路桥规》规定,当矩形截面受弯构件符合以下公式时,可不进行斜截面抗剪承载力的验算,而仅需按构造要求配置箍筋。当时,需设斜筋,其中:(3-7)(3-8)(2)计算参数a.腹筋设计①截面尺寸检查:根据构造要求,梁顶层有10根Φ32钢筋通过1-1截面,截面有效高,则;梁顶层有15根Φ32钢筋通过2-2截面,截面有效高度,则;83
梁顶层有25根Φ32钢筋通过3-3,4-4,5-5,6-6截面,截面有效高度,则;故截面符合设计要求。②检查截面是否需要配置箍筋1-1截面2-2截面因为故可在盖梁跨中的某个长度范围内按构造配置箍筋,其余区段按计算配置腹筋。③计算剪力图分配(图3-15-1所示),,弯起区段长度,,,即在长度内可按构造配置箍筋。83
图3-15-1盖梁剪力分配图Fig3-15-1Sheardistributionmap图3-15-2盖梁剪力分配图Fig3-15-2Sheardistributionmap悬臂部分:(图3-15-2所示),83
,弯起区段长度,,,b.箍筋设计箍筋采用R235级钢筋取直径Φ10(满足>8m且大于),其(3-9)C35混凝土,其;斜筋采用HRB400级钢筋,其。(3-10)其中需满足且,但当时,需满足且。1-1截面故取2-2截面故取83
3-3截面故取;因为需满足故取,综上,设计箍筋间距取。c.弯起钢筋及斜筋设计设焊接钢筋骨架的架立钢筋(HRB400)为φ14,钢筋重心至盖梁的上边缘距离,故取。弯起钢筋的弯起角为45°,弯起末端与架立钢筋焊接。为了得到每对弯起钢筋分配的剪力,由各排弯起的钢筋的末端折点应落在前一排弯起钢筋的弯起点。首先计算弯起钢筋的上下弯起点的垂直距离。图3-16钢筋弯起示意图Fig3-16Schematicdiagramofsteelbent3-3右截面:,故仅弯起一排钢筋。表3-11-1弯起钢筋计算表83
Table3-11-1Bentsteelcalculator1392.2距3-3截面距离/mm1550分配的计算剪力值/KN2114.67需要的弯起钢筋面积12083.2可提供的弯筋面积17φ32=13671.4弯筋与梁轴交点到3-3截面的距离/mm875.93-3左截面:,故弯起一排钢筋。表3-11-2弯起钢筋计算表Table3-11-2Bentsteelcalculator1376.6距3-3截面距离/mm80分配的计算剪力值/KN904.450需要的弯起钢筋面积5168.01可提供的弯筋面积8φ32=6433.6弯筋与梁轴交点到3-3截面的距离/mm768.3(3)各截面抗剪强度验算见表3-12:(3-11)(3-12)(3-13)(3-14)(3-15)表中,箍筋间距。表3-12各截面抗剪强度验算表83
Table3-12Shearstrengthofeverysectionchecking截面号1-12-23-3左右左右左右-65.239-2752.260-2927.148-2927.148-3059.6286355.203b/mm240024002400/mm965.9154015401761.8022808.962808.96P0.3470.3260.5440.187%0.187%0.187%2504.5113981.7034098.590/°0450-2569.75-5256.771-6908.8516908.851-7158.2182256.613截面号4-45-56-6左右左左右左6343.6833626.5333269.413189.38610.82610.826b/mm240024002400/mm1540154015402808.962808.962808.96P0.5440.5440.5440.187%0.187%0.187%4098.5904098.5904098.5900002245.093-472.057-829.177-3909.204-4087.764-4087.7643)各截面抗扭强度验算(1)选取4号墩进行验算按《公路桥规》规定,截面在承受弯剪扭共同作用时符合(3-16)式时,可不进行构件的抗扭承载力计算,仅需按构造要求配置钢筋。83
(3-16)且在弯剪扭共同作用下,截面尺寸必须符合:(3-17)(2)验算抗扭强度采用的公式:(3-18)抗扭纵筋:,其中ζ=1.2(3-19)(3)盖梁各截面剪力及扭矩计算列于表3-13表3-13各截面剪力及扭矩计算表Table3-13shearforceandtorquemomentofeverysectioncalculation截面号荷载情况1-12-23-34-45-56-6剪力/KN左-65.239-2927.148-3059.6286343.6833269.41310.826右-2752.260-2927.1486335.2033626.533189.38610.826弯矩/KN·m15.40224.02224.02224.02224.02224.022285.019444.518444.518444.518444.518444.518505.181505.181505.181505.181505.181505.1811047.2831265.8371265.8371265.8371265.8371265.837(4)和相应的计算a.制动力:T=30.027KN;温度影响力:H=555.647KN;汽车偏载:P=B2-B1=1228.967-178.605=1050.362KNb.盖梁各截面抗扭强度验算抗扭纵筋的抗拉强度设计值为:抗扭箍筋的抗拉强度设计值为:83
,,取,则盖梁各截面抗扭强度验算见表3-14表3-14-1截面抗扭强度验算表Table3-14-1Calculationofeverysectiontorsionalstrength截面1-12-23-3-65.239-2751.260-2927.148-2927.148-3059.6286355.2031047.2831265.8371265.837b/mm240024002400/mm965.915401540h/mm1025.9160016001.4871.4470.8720.8720.8550.585203.894249.55843.82543.82550.781127.9284588.8055616.5121164.7251164.7251349.5933399.908+3144902.8055930.5121478.7251478.7251663.5933713.908实需抗扭钢筋抗扭纵筋444444φ10箍筋333333表3-14-2截面抗扭强度验算表Table3-14-2Calculationofeverysectiontorsionalstrength截面4-45-56-66343.6833626.5333269.413189.38610.82610.8261265.8371265.8371265.837b/mm240024002400/mm15401540154083
h/mm1600160016000.5850.7920.8311.4331.4611.461127.92868.78257.638-114.371-122.372-122.3723399.9081828.0001531.829-3039.606-3252.247-3252.247+3143713.9082142.0001845.829-2725.607-2938.247-2938.247实需抗扭钢筋抗扭纵筋444444φ10箍筋3333333.4墩柱计算3.4.1恒载计算选择4号墩台1)一孔上部构造恒载:(867.85+783.31+894.73)×2×2=10183.56KN2)盖梁自重(半边):766.506kN3)一根墩柱自重(当=8m时):4)承台自重:5)桩身每米自重:3.4.2活载计算1)水平荷载:制动力与温度影响力总和为:H=585.674kN2)垂直荷载:公路-I级荷载:83
单孔单列:双孔单列:3.4.3墩柱配筋设计1)双柱反力横向分布系数计算(1)公路-I级荷载单列布载(2)公路-I级荷载双列布载(3)公路-I级荷载三列布载2)活载内力计算公路-I级荷载,双孔布载产生的支点反力最大,单孔布载产生的偏心弯矩最大。(1)最大最小垂直力计算表见表3-15。1+μ=1.1724。表3-15最大最小垂直力计算表Table3-15Calculationofthebiggestandsmallestverticalforces荷载情况最大垂直力最小垂直力(1+μ)×B×(1+μ)×B×汽车-Ⅰ级双孔,双列357.212100.7242457.5340.9892850.2490.1131.693535.8153151.0863686.3010.8423638.9720.158682.84783
双孔,三列(2)相应于最大最小垂直力时的弯矩计算见表3-16。表3-16相应最大最小垂直力时的弯矩计算Table3-16Calculationofmomentsaccordingtothebiggestandsmallestverticalforces荷载情况A墩底弯矩/KNmB墩底弯矩/KNm7.5H/20.35()×(1+μ)×7.5H/20.35()×(1+μ)×公路-Ⅰ级双孔双列357.212100.7240.9890.011707.5647.870双孔三列535.8153151.0860.8420.158903.593169.558制动力30.027112.60112.60温度影响力555.6472083.682083.68注:表中1+μ=1.1724(3)最大弯矩计算见表3-17。3)墩柱底截面内力组合表见表3-18。表3-17最大弯矩计算Table3-17Calculationofthebiggestmoments荷载情况公路-Ⅰ级制动力温度影响力单孔双列单孔三列30.027555.6470083
982.1341473.2010.9890.8420.0110.158垂直力(1+μ)×()×1138.7881454.286(1+μ)×()×12.666272.895A墩底弯矩7.5H/2112.602083.680.35()×(1+μ)×398.576509.0B墩底弯矩7.5H/2112.602083.680.35()×(1+μ)×4.43395.513表3-18内力组合表Table3-18Combinationofinnerforce截面位置内力名称A柱底截面B柱底截面1上部恒载2545.882545.882墩帽自重766.506766.5063墩柱自重353.25353.254公路-Ⅰ级双孔双列2850.249707.56431.6937.8705公路-Ⅰ级双孔三列3638.972903.593682.847169.55883
6公路-Ⅰ级单孔双列1138.788398.57612.6664.4337公路-Ⅰ级单孔三列1454.286509.00272.89595.5138温度影响力555.6472083.68555.6472083.689制动力30.627112.6030.627112.60101+2+3+4+8+98941.703573.963064.544995.725573.962084.968111+2+3+5+8+910045.916573.963338.985907.341573.962311.331121+2+3+6+8+96545.658573.962631.961009.087573.962080.156131+2+3+7+8+96987.355573.962786.555333.408573.962207.668141+2+3+48389.112990.594443.13311.018151+2+3+59493.3241265.035354.749237.381161+2+3+65993.066558.0064416.4956.206171+2+3+76434.763712.64780.816133.718注:本表内力组合按照设计规范JTGD60-2004规定。4)墩柱强度验算(1)由内力组合表得知,以下三种组合控制设计:a.恒载+双孔三列汽车荷载+制动力+温度影响力:=10045.916KN,=3338.98KNmb.恒载+单孔三列汽车荷载+制动力+温度影响力:=6987.355KN,=2786.55KNmc.恒载+双孔三列汽车荷载:=9493.324KN,=1265.03KNm(2)墩柱配筋设计墩柱采用C35混凝土,主筋采用HRB400钢筋,并取主筋保护层厚度c=60mm,则:,83
圆柱截面:假定按墩柱一端固定,一端自由计算。则有:对于此构件需考虑构件在弯矩作用平面内的变形对轴向力偏心距的影响,即应将轴向力对截面重心轴的偏心距乘以偏心距增大系数。对,(3-20)故取(3-21),故取(3-22)(3-23)对,,故取,故取对,83
,故取,故取利用公式:(3-24)(3-25)式中为轴向力的偏心距,应乘以偏心增大系数A、B为有关混凝土承载力的计算系数,按规定查表;C、D为有关纵向钢筋承载力的计算系数,按规定查表。按上两式列表进行计算,结果见表3-19。表3-19配筋系数表Table3-19Theparametersofreinforcedη和ξABCDρ1.3730.3320.601.49080.66510.50211.78560.013310141.72510045.9161.011.3780.3990.461.04900.5982-0.19031.90810.00697135.3776987.3551.021.4940.1330.792.09260.59821.59381.14960.003214235.19493.3241.5注:系数A,B,C,D由设计规范(JTGD62-2004)附录C查得。83
3.4.4墩身裂缝计算钢筋混凝土构件计算的最大裂缝宽度不应超过0.20mm。按照设计规范(JTGD62-2004)第6.4.5条的规定,裂缝计算公式:(mm)(3-26)(3-27)对组合:恒载+单孔双列汽车荷载+温度力+制动力对于带肋钢筋,=1.0。已知,,,,由于,故取。取44根φ32钢筋,则则83
,满足要求。3.5桩基的设计参照JTGD63-2007《公路桥涵地基与基础设计规范》设计。计算方法:按m法计算。承台底内力组合见表3-20。由表3-20可知,控制强度设计的荷载组合为:恒载+单孔三列汽车荷载+温度影响力+制动力:=15420.86KN;=573.96KN;=5151.027KNm。1)桩长估算(1)按允许应力法进行承台底垂直荷载的组合:恒载+双孔三列汽车荷载:=10357.372+4321.819=14679.191KN由此荷载控制设计。(2)桩长估算:采用2根直径1.3m的钻孔桩基础,那么作用于每根桩顶的外力为:表3-20承台底内力组合表Table3-20Combinationofinnerforceforbearingplatformend内力荷载名称1恒载10357.3722公路-Ⅰ级双孔,双列2881.942715.4343公路-Ⅰ级双孔,三列4321.8191073.1514公路-Ⅰ级单孔,双列1151.454403.0095公路-Ⅰ级单孔,三列1727.181604.5136温度影响力555.6474167.367制动力30.027225.2083
81+216463.5651001.60891+318479.3931502.411101+414040.882564.213111+514846.899846.318121+2+6+717037.525573.965306.317131+3+6+719053.55573.965807.12141+4+6+714614.84573.964868.922151+5+6+715420.86573.965151.027注:①表中恒载N=(2545.88+766.506+353.25)×2+3026.1=10357.372KN;②本表内力组合按设计规范(JTGD60-2004)的规定办理。桩的容许承载力按下式计算:,式中(3-28)当采用冲击钻头钻孔时,成孔直径为d+0.1m。则:(3-29)其中,,,,则故有:根据本设计计算桩长处的地基条件,为安全起见,桩长取。2)桩基强度验算(1)确定顺桥向桩的计算宽度,故取(2)桩的变形系数,在此范围内仅有一层土,即砾石。83
则(3-30)桩基采用C35混凝土,,(3)桩顶内力分配桩的计算长度为:,故可以按照弹性桩进行计算。a.值的计算(3-31)对钻孔桩:,,,,土的内摩擦角,则,故取,故由,取,,则有,,b.计算承台发生位移时引起的基桩反力83
c.计算承台底位移a,c,β;;d.计算外力作用下各桩顶内力轴向力:水平力:弯矩:校核:由计算可知,桩顶内力为:;;(4)求最大冲刷线以下深度Z处截面上的弯矩MZ以及桩侧水平应力a.求:无量纲系数及由《基础工程》中表4-13查得,值计算见表3-20。表3-21值计算表Table3-21Combinationof83
z295.9341287.2950001.00001287.2951287.2950.20.410.1970.99858.2991284.7201345.5940.40.830.3770.986111.5671269.2731380.8400.61.240.5290.959156.5491234.5161391.0650.81.650.6460.913191.1731175.3001366.4731.02.070.7230.851213.9601095.4881309.4481.22.480.7620.774225.502996.3661221.8681.42.890.7650.687226.390884.3721110.7621.63.310.7370.594218.103764.653982.7561.83.720.6850.499202.715642.360845.0752.04.130.6140.407181.703523.929705.6322.24.550.5320.320157.437411.934569.3712.44.960.4430.243131.099312.813443.9122.65.370.3550.175105.057225.277330.3343.06.200.1930.07657.11597.834154.9493.57.230.0510.01415.09318.02233.115b.求无量纲系数及由《基础工程》中表4-13查得,值的计算见表3-22。表3-22值计算表Table3-22Combinationof26.663115.983/KN/m²00000000.20.4130.4240.25811.30529.92441.2290.40.8260.7210.40019.22446.39365.6170.61.2400.9020.45024.05052.19276.2420.81.6530.9790.43026.10349.87375.9761.02.0660.9700.36125.86341.87067.7331.22.4790.8950.26323.86330.50454.3671.42.8930.7720.15120.58417.51338.0971.63.3060.6210.03916.5584.52321.0811.83.7190.457-0.06412.185-7.4234.76283
2.04.1320.294-0.1517.839-17.513-9.6742.24.5450.142-0.2193.786-25.400-21.6142.44.9590.008-0.2650.213-30.735-30.5222.65.372-0.104-0.290-2.773-33.635-36.4083.06.198-0.262-0.284-6.986-32.939-39.9253.57.231-0.367-0.199-9.785-23.081-32.866(5)桩截面强度验算由表3-20可知,桩截面最大弯矩发生在Z=1.24m处,故只需对此处桩截面的强度进行验算。该截面处桩的内力为:,桩基采用C35混凝土:HRB400钢筋:取c=6cm,那么对于多排桩,由于,故,故。当,时,根据公式有:(3-33)83
进行桩基配筋设计,计算见表3-23。表3-23配筋系数表Table3-23Theparametersofreinforced/mmεABCDρ/KN/KN3590.541.29960.64830.19411.87440.00218897.0353868.0532.3注:①系数A,B,C,D由设计规范(JTGD62-2004)附录C查得;②桩身材料是足够安全,可不进行桩身裂缝验算。(6)桩顶水平位移验算a.桩在最大冲刷线处的水平位移和转角(,)的计算(3-34)当,Z=0时,通过查表可得到:,故符合m法计算要求。通过查表可得到:,故b.墩顶纵向水平位移验算在公式,,其中83
则墩顶纵向水平位移:水平位移容许值;满足要求。4桥台的设计4.1桥台类型和主要材料桥台采用墙式埋置式框架式桥台。主要材料:混凝土采用C35混凝土;主筋采用HRB400钢筋。4.2桥台一般构造尺寸的拟定埋置式桥台是将台身埋在锥形护坡中,只露出台帽在外以安置支座和上部构造。这样,桥台所受的土压力大为减少,桥台的体积也相应的减小。埋置式框架式桥台结构本身存在着斜杆,能够产生水平力以平衡土压力,稳定性较好。其构造尺寸如图4-1。图4-1桥台一般构造图/cm83
Fig4-1Generalstructureofabutment/cm4.3台帽计算4.3.1荷载计算1)上部构造恒载支点反力每片边梁(1号梁)的支点反力:1735.7KN2号中梁支点反力:1566.62KN3号中梁支点反力:1789.46KN2)活载支点反力(1)计算横向分布系数公路-Ⅰ级荷载(四列或五列)作对称布置或非对称布置,分配系数的假定同上文的桥墩即荷载非对称布置时,用铰接板法计算,荷载对称布置时用杠杆法计算。公路-Ⅰ级荷载的分配系数计算过程已在桥墩部分计算完毕,结果见表4-1。表4-1横向分布系数表(五片梁)Table4-1Horizontaldistributioncoefficient(fivebeams)荷载情况公路-Ⅰ级四列对称布置0.1450.855110.8550.145非对称布置0.73530.74990.75360.70160.60140.5296公路-Ⅰ级五列对称布置0.511110.5非对称布置0.81580.84410.87890.87960.83660.7993(2)冲击系数按上部结构计算得到1+μ=1.1724(3)绘制反力影响线,如图4-2所示。按公路-I级计算得反力最大值。图4-2支点反力影响线/m83
Fig4-2Theinfluencelineofbearingreaction/m单列:四列:五列:(4)各种活载的各梁反力的计算见表4-2。表4-2各梁活载反力/KNTable4-2Reactionofliveloadforeverybeams/KN梁号对称布置非对称布置公路-Ⅰ级四列1898.74×0.145=275.3171898.74×0.7353=1396.1441898.74×0.855=1623.4231898.74×0.7499=1423.8901898.74×1=1898.741898.74×0.7536=1430.4901898.74×1=1898.741898.74×0.7016=1332.1561898.74×0.855=1623.4231898.74×0.6014=1141.9021898.74×275.3171898.74×0.5296=1005.573公路-Ⅰ级四列2373.425×0.5=1186.7132373.425×0.8158=1936.2402373.425×1=2373.4252373.425×0.8441=2003.4082373.425×1=2373.4252373.425×0.8789=2086.0032373.425×1=2373.4252373.425×0.8789=2086.0032373.425×1=2373.4252373.425×0.8366=1985.6072373.425×0.5=1186.7132373.425×0.7993=1897.0793)台身反力按双悬臂简支梁计算,如图4-3。83
图4-3台身反力/cmFig4-3Reactionofabutmentbody/cm上部构造恒载、活载作用时,台身反力计算见表4-3。表4-3上部构造恒载、活载作用时,台身反力计算表Table4-3Calculationofpierreaction,whenliveanddeadloadofupperstrucureacting台身反力上部荷载公路-Ⅰ级对称非对称/KN1.31582283.834362.2621837.0460.98951550.1701606.3771408.9140.66321186.7701259.244948.9660.3368602.690639.496448.6700.01117.23317.85812.561-0.3158-548.134-86.945-317.560合计5092.5633798.2924338.597/KN1.31582283.8341561.4772496.1770.98951550.1702348.5041964.7580.66321186.7701574.0551384.5390.3368601.259799.370702.5660.01117.23326.10822.037-0.3158-548.134-374.764-611.46583
合计6641.3025934.755958.6124.3.2内力计算1)上部构造恒载、活载所产生的剪力计算:见表4-4。表4-4恒载、活载剪力计算表Table4-4Calculationofshearforcesforliveanddeadloa荷载情况1-12-23-34-45-56-6上部恒载-1735.7-1735.73356.8631790.2430.9830.983公路-Ⅰ级五列非对称-1936.240-1936.2402402.357398.949-1687.716-1687.716对称-1186.713-1186.7132611.579238.154-2135.271-2135.2712)上部构造恒载、活载产生的台帽各截面弯矩计算见表4-5。表4-5恒载、活载弯矩计算表/KNmTable4-5Thebendingmomentofliveanddeadloadcalculation/KNm截面位置上部恒载公路-Ⅰ级五列对称非对称2-2=-1.85-3211.045-2195.419-3582.0443-3=-4.95-8591.715-5874.229-9584.3884-4-5.05-8765.285-5992.901-9778.012+0.1805.256379.829433.860-8256.029-13682.72-22510.5845-5-8.15-14145.955-9671.711-15780.356-3.1-4856.522-7357.618-6210.565+3.216296.20212154.53413883.510-2706.275-4874.795-8107.4116-6-9.7-16836.29-11511.116-18781.528-4.65-7284.783-11036.426-9315.84783
-1.55-2773.663-3678.809-3233.305+4.7524189.67428190.06328303.407-2705.0621963.712-3027.2733)台帽自重反力、剪力、弯矩计算。耳墙:挡块:背墙:(每米重16.1KN)台帽:(每米重96kN)合计:(32.904+10.086)×2+7.479×2+270.459+1.125×2+139.2×2+1132.8=1784.847KN图4-4台帽各截面内力计算图/cmTable4-4Interalforcesofcopinginsectionsonbentcap/cm每片墙反力:台帽各截面自重剪力计算见表4-6。表4-6台帽自重剪力计算表83
Table4-6Calculationofbentcapshearforces截面计算式Q/KN1-1左32.904+10.086+7.479+1.125+16.1×0.85+0.5×(0.7+1.0259)×1.05×2.4×25-119.645右-119.6452-2左32.904+10.086+7.479+1.125+16.1×2.7+139.2-239.305右-239.3053-3左32.904+10.086+7.479+1.125+16.1×3.85+139.2+96×1.15-344.664右G-344.664547.764-4左547.76-(16.1+96)×0.1536.55右536.555-5左536.55-(16.1+96)×3.1189.04右189.046-6左189.04-(16.1+96)×1.5515.285右15.285台帽各截面自重弯矩的计算见表4-7。表4-7台帽自重弯矩计算表Table4-7Calculationofbentcapbending-moment截面部分重力/KN/mM/KNm1-132.904+10.086=42.991.05-0.1=0.95-40.8417.4790.95-7.105背墙16.1×0.85=13.6850.5×0.85=0.425-5.816270.4591.05-0.2=0.85-229.890台帽0.5×(0.7+1.0259)×2.4×25=51.7770.4920-25.474合计-309.1262-242.992.9-0.1=2.8-120.3727.4792.8-20.941背墙16.1×2.7=43.470.5×2.7=1.35-58.685270.4592.9-0.2=2.7-730.239台帽139.20.8576-119.37883
合计-1049.6153-342.994.05-0.1=3.95-169.8117.4793.95-29.542背墙16.1×3.85=61.9850.5×3.85=1.925-119.321270.4594.05-0.2=3.851041.267台帽139.2+96×1.15=249.60.575-143.52合计-1503.3614-442.994.15-0.1=4.05-174.1107.4794.05-30.290背墙16.1×3.95=63.5950.5×3.95=1.975-125.600270.4594.15-0.2=3.95-1066.678台帽139.2+96×1.25=259.20.625-162G892.4240.189.242合计-1469.436续下表接上表截面部分重力/KN/mM/KNm5-542.997.25-0.1=7.15-307.3797.4797.15-53.475背墙16.1×7.05=113.5050.5×7.05=3.525-400.105270.4597.05-0.2=3.525-1906.736台帽139.2+96×4.35=556.82.175-1211.04G892.4243.22855.757合计1022.5996-642.998.8-0.1=8.7-374.0137.4798.7-65.067背墙16.1×8.6=138.460.5×8.6=4.3-595.378270.4598.8-0.2=8.6-2325.947台帽139.2+96×5.9=705.62.952081.52G892.4244.754239.01483
合计-1202.9114)内力汇总见表4-8。4.3.3截面验算采用C35混凝土,主筋用HRB400,设计强度,混凝土设计强度:,,保护层取6cm。1)荷载组合荷载组合原则JTGD60-2004第4.1.6进行;结构重要性系数。荷载组合的结果列于表4-9。表4-8内力汇总表Table4-8Thesummaryofinterforce截面位置恒载公路-Ⅰ级上部构造台帽合计1-1Q/KN左0-119.645-119.6450右-1735.7-119.645-1855.345-1936.240M/KN·m+0000-025.47425.47402-2Q/KN左-173507239.305-1975.005-1936.240右3356.863-239.3053117.558-1936.240M/KN·m+0000-3211.045119.3783330.4233582.0443-3Q/KN左3356.863-344.6643012.199-1936.240右1790.243547.762338.0032611.579M/KN·m+0000-8591.715143.528735.2359584.3884-4Q/KN左1790.243536.552326.7932611.57983
右0.983536.55537.533398.949M/KN·m+0000-8256.0291628418.02922510.5845-5Q/KN左0.983189.04190.023398.949右0.983189.04190.023-2135.271M/KN·m+0000-2706.2751211.043917.3158107.4116-6Q/KN左0.98315.28516.268-2135.271右0.98315.28516.368-2135.271M/KN·m+0000-2705.0622081.524786.5823027.273表4-9荷载组合表Table4-9Formofloadcombinatio截面位置组合Ⅰ组合Ⅱ组合Ⅲ1-1/KN左-143.574-119.645-119.645右-4937.15-3210.713-2629.841/KN·m+000-30.56925.47425.4742-2/KN左-5008.742-3330.373-2749.501右1030.6701962.192343.062/KN·m+000-9011.3695837.8544763.2413-3/KN左903.9021656.8312237.703右6461.8144166.1081293.371/KN·m+000-23900.4259144.30712568.9904-4/KN左6448.3624154.8983371.425右1203.568816.797697.11383
/KN·m+000-41616.45224175.43817422.2635-5/KN左786.556469.287349.603右-276.352-1304.667-664.085/KN·m+000-16051.1539592.5037160.2796-6/KN左-2969.858-1478.422-837.840右-2969.858-1478.422-837.840/KN·m+000-9982.0816905.6735997.491从表4-9可以看出,截面均以组合Ⅰ控制设计。2)正截面强度计算6-6截面:c=6cm,=160-6=154cm,b=240cm由有解得:将x值代入下式,采用45根Φ32钢筋,其面积其他截面的计算方法相同,计算结果列表4-10表4-10正截面钢筋用量表Table4-10Amountofsteelofcross-section截面1-12-23-34-45-56-6计算钢筋面积94187355561821257563501035689.3实际用钢筋用量根数624701574545面积4825.219300.856294126259.4361893618983
4.4台墙计算4.4.1垂直荷载计算1)恒载计算(1)上部构造:;(2)耳墙:;(3)挡块:;(4)背墙:背墙后填土:(5)台帽:(6)台墙(3-3截面以上):台墙上土重:台墙(4-4截面以上):台墙上土重:(7)承台:(8)承台以上土重:2)恒载对台墙各截面所产生的弯矩a.2-2截面:83
b.3-3截面:c.4-4截面:83
d.5-5截面:3)活载对台墙产生的反力公路-I级荷载对称布置,从台帽计算中知,公路-I级双孔五列布载,梁端反力R=3665.74KN,则1片台墙的反力4)活载对各截面所产生的弯矩见表4-11。表4-11活载偏心弯矩表Table4-11Eccentricbendingmomentofliveload截面荷载2-23-34-45-5公路-ⅠR/KN1832.871832.871832.871832.8783
级(非对称布置)00.511M/KNm0916.4351832.871832.874.4.2水平力计算1)由填土自重引起的土压力:=18kN/m³,=35。(1)台前溜坡土压力(根据河道水流情况,溜坡不可能被冲毁,考虑按主动土压力计算。溜坡被冲情况验算从略)计算公式如下:(4-1)式中:B=2×1.5=3.0m(4-2)则a.3-3截面H=4.6234mb.截面4-4H=8.081mc.承台部分83
(2)由台后填土自重引起的土压力a.各截面单位土压力(4-3)1-1截面:;2-2截面:;3-3截面:;4-4截面:;5-5截面:。b.各部分土压力计算背墙:;;台帽:;;台墙中部:;;83
台墙底:;;承台:;。c.各截面土压力总和及其所产生的弯矩1-1截面:。2-2截面:;;;。3-3截面:;;;;。4-4截面:;;;83
;;。5-5截面:;;;;;;。2)由活载引起的水平土压力台后公路-Ⅰ级荷载,桥上无活载时,由汽车荷载换算的等代均布土层厚度为:式中:为桥台后填土的破坏棱体长度,对于台背为竖直时;,而;;所以,。在破坏棱体长度范围内只能放两个重轴,因是四车道,故单位土压力各部分土压力计算:83
背墙:;台帽:;台墙中部:;台墙底部:;承台:。各截面水平土压力总和及弯矩计算:1-1截面:。2-2截面:;;;。3-3截面:;;;;。4-4截面:;83
;;;;。5-5截面:;;;;;;。3)地震水平力计算桥台的水平地震力按下式计算:(4-4)对于地震动峰值加速度0.05g的地区式中各项分别等于:=1.7,=0.35,=0.2;为台身重力,则。各部水平地震力计算:耳墙:;;挡块:;;背墙:;;83
台帽:;;台墙中部:;;台墙底:;;承台:;。水平地震力对各截面产生的弯矩计算:2-2截面:;;;;;。3-3截面:;;;;;;。4-4截面:;;83
;;;;;。5-5截面:;;;;;;;;。4)地震土压力计算地震时作用于台背的主动土压力可按下式计算:式中:=1.7,=0.35,=0.2,,故有其作用点在距计算截面的0.4H处。各截面地震土压力计算:83
1-1截面:;;。2-2截面:;;。3-3截面:;;;。4-4截面:;;;。5-5截面:;;;。5)支点摩阻力计算83
。(4-5)作用点距台帽顶0.081m。各截面的弯矩为:1-1截面:;2-2截面:;3-3截面:;4-4截面:;5-5截面:。6)内力汇总及组合,见表4-12。表4-12内力组合表Table4-12Combinationofinnerforce编号项目2-23-3P/KNH/KNM/KNmP/KNH/KNM/KNm1上部构造5091.785091.782545.8632桥台899.07204.3821329.813790.9883桥梁1832.871832.87916.4354台前土压力-96.384148.5015台后土压力174.915-176.669442.233-1108.0996台后公路-Ⅰ级土压力64.984-98.48394.9-418.2517结构地震力±106.198±119.688±149.038±149.0388地震土压力240.895-291.965387.247387.2479支座摩阻力254.589±427.964254.589254.589组合Ⅰ1+2+4+5+39755.038209.89833.25610271.930415.019415.0191+2+4+5+67189.02300.876107.3827705.912547.879547.879组合Ⅱ1+2+4+5+3+99755.038515.405-480.30110271.930720.526720.5261+2+4+5+6+97189.02606.383-406.1757705.912853.386853.386编号项目4-45-5P/KNH/KNM/KNmP/KNH/KNM/KNm1上部构造5091.785091.785091.785091.7883
2桥台2252.8221508.0247944.031-3884.0143桥梁1832.871832.871832.871832.874台前土压力-294.449793.147-311.822387.3925台后土压力482.228-3282.2581226.732-5162.1156台后公路-Ⅰ级土压力124.816-857.683159.363-1170.2867结构地震力±238.467±2464.676±395.908±1963.2038地震土压力731.762366.814919.2735992.1119支座摩阻力254.5892102.475254.589±3024.772组合Ⅰ1+2+4+5+311379.54225.335-590.79715601.829914.91-1714.3301+2+4+5+68813.522400.077-855.13615642.9731138.018-5918.749组合Ⅱ1+2+4+5+3+911379.54530.85415601.8291220.417-5344.0561+2+4+5+6+98813.522705.58415642.9731443.91-8973.7824.4.3截面验算1)台帽底面(2-2截面),(为荷载组合表中的计算弯矩。)2)台墙中部(3-3截面)3)台墙底部(4-4截面)4)钢筋配置2-2截面:83
,,,,由有1.0×480.301=16.1×10³×1×(1.83-)解得:将x值代入下式,采用6根Φ32的钢筋,其面积3-3截面:,,,,由有1.0×4135.673=16.1×1000×1×x×(2.83-)解得:将x值代入下式,:采用8根Φ32钢筋,其面积4-4截面:,,,,由有1.0×2366.814=16.1×1000×1×x×(3.83-)解得:83
将x值代入下式,采用12根Φ32钢筋,其面积4.5背墙计算土压力及活载水平力所产生的弯矩的荷载效应:每米长度内=45-4=41cm,,由有1.0×7.59=16.1×1000×1×x×(0.41-)解得:将x值代入下式,A每米长度内采用6根Φ14钢筋,其截面积为:。4.6耳墙计算按挡土墙土压力计算。83
4.6.1活载等代土层厚度的计算,B=l+a+Htan30°式中:l为汽车的前后轴轴距,l=12.8m;A为车轮着地长度,a=0.2m;H为耳墙高度,取平均高度H=1.0155m。对于公路-I级荷载,B=12.8+0.2+1.0155tan30=13.586m4.6.2水平土压力计算根部(墙高1.431m)端部(墙高0.6m)总土压力重心4.6.3截面计算=400-60=340mm由有1.0×20.315=16.1×1000×1.681×x×(0.34-)解得:83
将x值代入下式,A:采用8根Φ14钢筋,其截面积为:悬臂自重弯距很小,验算从略。4.7桩基的设计计算方法:按m法计算。以5-5截面的荷载组合1+2+4+5+6+9控制桩基设计。截面5-5(承台底面)中心受力情况为:计入荷载效应系数时:P=15642.973KN,H=1443.91KN,M=-8973.782KNm;不计入荷载效应系数时:P=14868.681KN,M=-7762.015KNm1)桩入土长度的计算桩基顶部竖向力为:桩的容许承载力按下式计算:式中:当采用冲击钻头钻孔时,成孔直径为d+0.1m。则:,其中,,,则故有:,得。根据本设计计算桩长处的地基条件,为安全起见,桩长取l=18m。2)桩基强度验算83
(1)确定顺桥向桩的计算宽度,故取=4.5m(2)桩的变形系数,在此范围内有一层土:砾石:桩基采用C35混凝土,,(3)桩顶内力分配桩的计算长度为:,故可以按照弹性桩进行计算。a.值的计算对钻孔桩:,,,,,土的内摩擦角,则,取d0=5.90m。故由,取,,则有,,83
b.计算承台发生位移时引起的基桩反力c.计算承台底位移a,c,β,,d.计算外力作用下各桩顶内力轴向力:水平力:弯矩:校核:由计算可知,桩顶内力为:;;(4)求最大冲刷线以下深度Z处截面上的弯矩MZ以及桩侧水平应力83
a.求MZ:无量纲系数及由《基础工程》中表4-13查得,值计算见表3-20。b.求无量纲系数及由《基础工程》中表4-13查得,值的计算见表4-14。表4-13值计算表Table4-13Combinationofz745.407-587.9120001.0000-587.912-587.9120.20.410.1970.998146.845-579.681-439.8910.40.830.3770.986281.018-563.808-298.6630.61.240.5290.959394.320-536.764-169.4880.81.650.6460.913481.533-500.313-55.2311.02.070.7230.851538.929-455.04438.6161.22.480.7620.774568.000-403.896112.9561.42.890.7650.687570.236-349.220166.3401.63.310.7370.594549.365-293.368200.1451.83.720.6850.499510.604-239.280217.2362.04.130.6140.407457.680-142.863218.4002.44.960.4430.243330.215-142.863187.3522.85.7850.270.120201.260-70.549130.711表4-14值计算表Table4-14Combinationof26.663115.983/KN/m²83
00000000.20.4130.4240.25816.423-7.8968.5270.40.8260.7210.40027.978-12.24215.7360.61.2400.9020.45035.001-13.77221.2290.81.6530.9790.43037.989-13.16024.8291.02.0660.9700.36137.640-11.04826.5921.22.4790.8950.26334.730-8.04926.6811.42.8930.7720.15129.957-4.62125.3361.63.3060.6210.03924.097-1.19422.9031.83.7190.457-0.06417.7331.95919.6922.04.1320.294-0.15111.4084.62116.0292.44.9590.008-0.2650.3108.1108.4202.85.785-0.193-0.295-7.4899.0281.5393.57.231-0.367-0.199-14.2416.090-8.151(5)桩截面强度验算由表4-13可知,桩截面最大弯矩发生在Z=4.132m处,故只需对此处桩截面的强度进行验算。该截面处桩的内力为:;桩基采用C35混凝土:,HRB400钢筋:取c=6cm,则,,对于多排桩,由于,故,故。当,时,当,时,根据公式:83
进行桩基配筋设计,计算见表4-15。表4-15配筋系数表Table4-15Theparametersofreinforced/mmεABCDρ/KN/KN441.192.95780.16002.69280.38360.36%28586.044929.255.8731.082.82000.26092.49240.53560.29%26880.323008.858.9注:1.系数A,B,C,D由设计规范(JTGD62-2004)附录C查得。2.桩身材料足够安全,可不进行桩身裂缝验算。(6)桩顶水平位移验算a.桩在最大冲刷线处的水平位移和转角(,)的计算当,Z=0时,通过查表可得到:,故符合m法计算要求。,通过查表可得到:,故b.墩顶纵向水平位移验算在公式中,,其中,83
则墩顶纵向水平位移:水平位移容许值;满足要求。83
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