第一章混凝土橋課程設(shè)計(jì)任務(wù)書（4）主梁跨徑：主梁全長40m；（5）結(jié)構(gòu)尺寸圖，根據(jù)預(yù)應(yīng)力混凝土簡支箱梁橋的構(gòu)造要求設(shè)計(jì)，可參照?qǐng)D1（3）《鐵路混凝土結(jié)構(gòu)耐久性設(shè)計(jì)暫行規(guī)定》（鐵建設(shè)函（2005）157號(hào)（4）《新建鐵路橋上無縫線路設(shè)計(jì)暫行規(guī)定》（鐵建設(shè)函（2003）205號(hào)精選范本（1）進(jìn)行上部結(jié)構(gòu)的構(gòu)造布置并初步擬定各部分尺寸。<1>主梁內(nèi)力計(jì)算<2>主梁預(yù)應(yīng)力鋼筋配置及驗(yàn)算<3>行車道板內(nèi)力計(jì)算及設(shè)計(jì)<4>繪制主梁設(shè)計(jì)圖（包括主梁構(gòu)造圖和配筋圖）設(shè)計(jì)計(jì)算書：設(shè)計(jì)計(jì)算說明書用Word文檔或手寫。整個(gè)說明書應(yīng)滿足計(jì)算過程完整、計(jì)算步驟清楚、文字簡明、符號(hào)規(guī)范的要求。封面、任務(wù)書和計(jì)算說明書用A4紙張打印，按封面、任務(wù)書、計(jì)算說明書的順序一起裝訂成冊(cè)，交指導(dǎo)老圖紙：要求圖面整潔美觀，比例適當(dāng)，圖中字體采用仿宋體，嚴(yán)格按制圖標(biāo)準(zhǔn)作圖。圖幅為A3圖第二章主梁縱向計(jì)算（2）《鐵路橋涵鋼筋混凝土和預(yù)應(yīng)力混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》（TB10002.3-2005（3）《京滬高速鐵路設(shè)計(jì)暫行規(guī)定》（鐵建設(shè)函（2004）157（1）線路情況：有砟橋面，雙線，線間距5.8m；。（2）環(huán)境類別及作用等級(jí)：環(huán)境作用等級(jí)為L1級(jí)；（3）施工方法：支架現(xiàn)澆施工。精選范本（1）截面類型為單箱單室等高度簡支箱梁，直線梁，梁端頂板、底板及腹板局部向內(nèi)側(cè)加強(qiáng);（2）橋跨布置：梁長為40m,計(jì)算跨度為38.5m；（3）橋面寬度：擋砟墻內(nèi)側(cè)凈寬9.6m,擋砟墻寬0.2m；人行道寬1.3m,人行道采用懸臂板方式；上頂板寬為12.6m=①結(jié)構(gòu)構(gòu)件自重：按《鐵路橋涵設(shè)計(jì)基本規(guī)范》（TB10002.1-2005第4.2.1條采用；②附屬設(shè)施（二期恒載二期恒載包括橋上軌道線路設(shè)備自重、道砟、防水層、人行道欄桿、擋砟墻、電纜槽及蓋板、電氣化立柱等附屬設(shè)施重量。橋面二期恒載取190+815/1000=190.815KN/m。①列車豎向活載縱向計(jì)算采用ZK活載；②列車豎向活載橫向計(jì)算采用ZK特種活載；③橫向搖擺力：取100kN集中荷載作用在最不利位置，以水平方向垂直線路中線作用于鋼規(guī)頂面。④人行道豎向靜荷載：按5kN/m。①風(fēng)力：風(fēng)力按《鐵路橋涵設(shè)計(jì)基本規(guī)范》（TB10002.1-2005第4.4.1條采用；②結(jié)構(gòu)溫度變化影響力：按《鐵路橋涵設(shè)計(jì)基本規(guī)范》（TB10002.1-2005辦理，整體升降溫25C,縱向溫度荷載按頂板升溫5C考慮。橫向計(jì)算按升溫、降溫兩種情況考慮溫度變化的影響力，其計(jì)算模式如下：③（4）特殊荷載:列車制動(dòng)力：橋上列車制動(dòng)力和牽引力按單線豎精選范本①脫軌荷載：不計(jì)動(dòng)力系數(shù)，亦不考慮離心力，只考慮一線脫軌荷載，其他線路上不作用列車活載;②地震力：按《鐵路工程抗震設(shè)計(jì)規(guī)范》辦理，地震基本烈度為七度。(1)預(yù)應(yīng)力鋼筋：采用高強(qiáng)度低松弛鋼絞線，鋼絞線公稱直徑為15.2mm,公稱面積為140mm2，規(guī)格為12-7?和15-7?5;標(biāo)準(zhǔn)強(qiáng)度pk=1860MPa；1000h后應(yīng)力松弛率不大于4.5%。(2)普通鋼筋：當(dāng)鋼筋直徑大于等于10mm時(shí)，采用HRB335鋼筋；當(dāng)鋼筋直徑小于10mm時(shí)，采用Q235鋼筋。(3)混凝土：現(xiàn)澆箱型梁采用C50混凝土，軸心抗壓標(biāo)準(zhǔn)值為33.5MPa,軸心抗拉標(biāo)準(zhǔn)值為3.1MPa后張法施加預(yù)應(yīng)力。采用OVM錨，進(jìn)行兩端張拉。預(yù)應(yīng)力管道采用塑料波紋管成孔，對(duì)規(guī)格為12-7?5的鋼絞線，采用內(nèi)徑為90mm,外徑為106mm的波紋管；對(duì)規(guī)格為15-7?的鋼絞線，采用內(nèi)徑為100mm,外徑為116mm的波紋管。管道摩擦系數(shù)=0.2，管道偏差系數(shù)k=0.0015,錨具變形和鋼束回縮量為6mm。7、混凝土及鋼筋的各項(xiàng)數(shù)據(jù)：(1)預(yù)應(yīng)力鋼絞線：抗拉計(jì)算強(qiáng)度為fp0.9fpk1674MPa，彈性模量為Ep1.95105MPa。在主力作用下，破壞強(qiáng)度安全系數(shù)K=2.0，則鋼絞線的抗拉強(qiáng)度設(shè)計(jì)值應(yīng)為彳呦上837MPa。K(2)普通鋼筋：對(duì)Q235鋼筋，彈性模量為Es2.1105MPa;在主力作用下，其容許應(yīng)力為s]130MPa。對(duì)HRB335鋼筋，彈性模量為Es2.0105MPa;在主力作(3)混凝土：對(duì)C50混凝土，彈性模量為Ec3.55104MPa;其彎曲受壓及偏心受壓時(shí)的容許應(yīng)力b]16.8MPa，有箍筋及斜筋時(shí)的主拉應(yīng)力容許值為[tp1]2.79MPa，純剪應(yīng)力容許值為[c]1.55MPa，局部承壓應(yīng)力容許值為[C1]13.4\AA(A為計(jì)算底面積，Ac為局部承壓面積)。預(yù)應(yīng)力混凝土結(jié)構(gòu)重度按26kN/m精選范本二、結(jié)構(gòu)尺寸擬定由于設(shè)計(jì)受到中一活載強(qiáng)度、工后徐變等多方面制約，梁高經(jīng)過反復(fù)比選，最后確定為3.2m等高度梁。2、上翼緣上翼緣懸臂寬度為3100mm,兩腹板間寬度為5286mm按構(gòu)造要求，頂板厚度不得小于200mm。故對(duì)人行道，受力較小，頂板厚度取為240mm；對(duì)行車道板，受力較大，在跨中頂板厚度取為340mm,在支點(diǎn)處則增大至750mm。3、腹板為保證腹板能夠承受相應(yīng)的剪力，構(gòu)造上要求腹板厚度不得小于150mm。同時(shí)，為了能夠在腹板中布置預(yù)應(yīng)力鋼束，取跨中腹板厚度為550mm,支座處腹板厚度則增大至1060mm受彎構(gòu)件的翼緣應(yīng)在與腹板相交處設(shè)置梗肋。上、下翼緣梗肋之間的腹板高度，當(dāng)無預(yù)應(yīng)力豎筋時(shí)，不應(yīng)大于腹板厚度的15倍。故取上、下梗肋之間的腹板高度為1910mm。4、下翼緣按構(gòu)造要求，底板厚度不得小于200mm，且在箱梁的端部必須設(shè)置橫隔板。故在跨中，底板厚度取為300mm,在支點(diǎn)處由于抗剪、抗彎的要求則增大至850mm。對(duì)于橋面的布置，可見下圖：L.L.-----------------------------------------------JpT11■ 25阿■■J-?_TIjjLBi■LK.精選范本三、荷載內(nèi)力計(jì)算（1）梁體自重gl:用CAD軟件對(duì)跨中截面和支座截面進(jìn)行面域計(jì)算可得：取主梁的一半為研究對(duì)象，設(shè)寬段長度為7m,窄段長度為13m,窄段截面在距支座中心線6.25m處開始發(fā)生變化，至距支座中心線1.25m處變化成寬段截面。由于主梁伸出支座段（伸出長度為0.75m）對(duì)于減小跨中截面彎矩有利，且其對(duì)支座截面產(chǎn)生的負(fù)彎矩（約為-112.19kN?m）也不是很大，所以，在計(jì)算主梁縱向受力時(shí)，忽略這部分恒載的作用。貝2L2244.740413398.82226.25294.767kN/m294.767按照《鐵路橋涵設(shè)計(jì)基本規(guī)范》（TB10002.1-2005第4.2.1條第四點(diǎn)的規(guī)定，當(dāng)全跨度上的豎向恒載不均勻時(shí)，但實(shí)際的不均勻值與平均值相差不大于平均值的10%時(shí)，可按均勻計(jì)算。由于此處的不均勻值已經(jīng)超過10%，故不能采用均勻值計(jì)算。此時(shí)，應(yīng)采用對(duì)影響線分段加載的方法進(jìn)行計(jì)算。根據(jù)其豎向恒載的變化，可分三段加載，其加載情況如下圖：酬gl1'g1g1窄244.74kN/m，其加載長度為26m；精選范本gigi9寬398.83kN/m，其加載長度均為6.25m由于一恒分三段加載，故恒載計(jì)算值也應(yīng)分三段累加，其值計(jì)算如下:ggig2244.740190.815435.555kN/mggg398.822190.815589.637/mggig2398.822l90.815589.637J/min3分別為各恒載加載段對(duì)應(yīng)的影響線面積2、活載（ZK活載）活載采用ZK活載，其換算均布荷載可在《京滬高速鐵路設(shè)計(jì)暫行規(guī)定》（鐵建設(shè)函（2004）157號(hào)）“附錄DZK標(biāo)準(zhǔn)活載的換算均布荷載值”中查得。（2）列車活載沖擊系數(shù):計(jì)算剪力時(shí),2=1.4940.851，L為梁的加載長度（m）對(duì)于本橋, 計(jì)算時(shí)為了偏于安全，都取1.1003（3）活載內(nèi)力計(jì)算公式:2精選范本活載內(nèi)力采用換算均布活載在影響線上加載計(jì)算求得，此外，根據(jù)《京滬高速鐵路設(shè)計(jì)暫行規(guī)定》建設(shè)函（2004）157號(hào)）第629條第1點(diǎn)的規(guī)定，對(duì)于單線和雙線的橋梁結(jié)構(gòu)，各線均應(yīng)計(jì)入ZK活載作用故，內(nèi)力計(jì)算為加載范圍內(nèi)同號(hào)影響線面積。3、彎矩及剪力計(jì)算其剪力、彎矩影響線如下圖：血圖3.4支座截面影響線圖對(duì)剪力影響線,嗎32-(16.255.7427m32響32^2613.0000m0.5073m0.5073mQ0.000g589.6375.7427435.55513.0000589.6370.50739347.38kN精選范本②ZK活載作用時(shí),1287.1284.9340.036.0對(duì)距支座1.25m,1.982m,6.25m的變截面，以及-和-處進(jìn)行類似計(jì)算，計(jì)算結(jié)果列于下表：主梁截面主梁截面恒載最大剪力Q說明：上表已計(jì)入ZK活載動(dòng)力系數(shù)1.10Q支點(diǎn)截面9347.383631.5704495.282202.536697.818178.793308.628610.43426.715662.222633.928296.14距支座1.25m距支座1.982m距支座6.25m83709.5633728.95說明：上表已計(jì)入ZK活載動(dòng)力系數(shù)1.100b04311.02主梁截面恒載63534.9325307.1988842.126727.2824096.0946905.3165314.84距支座1.982m距支座6.25m支點(diǎn)截面距支座1.25m本次計(jì)算只考慮主力的內(nèi)力組合，且未考慮支座不均勻沉降對(duì)橋梁受力的影響精選范本此時(shí)，內(nèi)力組合(主力)：自重+二期恒載+預(yù)加力+收縮徐變由已給圖紙可知鋼束具體布置數(shù)據(jù)如下:表4-1鋼束豎彎平彎信息鋼束號(hào)鋼束號(hào)彎起角度(°)彎起角度(°)40.852030.320432034204832031203320483204386202020表4-2鋼束豎彎起彎點(diǎn)至跨中距離計(jì)算表鋼束號(hào)y(mm)徑)y2(mm)y1(mm)x3(mm)x2(mm)x1(mm)3800089.0361730.800418.68817140.5134806424054.781425.2193718.7931045.28514525.9224804654036.539443.4616017.4641046.34712226.188610320.557589.44310797.749785.0397707.211840320.557819.44313597.749785.0394907.211436.5391033.46115967.4641046.3472276.188480001280.51218211.314558.052520.634表4-3各計(jì)算截面的鋼束位置及鋼束群重心位i)453.479883.4791144.1571574.157764.626350550750950506.521506.521675.843675.8439665966596659665未彎起未彎起未彎起610840y(mm)X距支座6.25m未彎起未彎起鋼束號(hào)643.610Xa54精選范本距支座1.982m距支座支點(diǎn)鋼束起彎點(diǎn)至跨中距離計(jì)算表8006108408000480480610840480480610840480480610840629062906290629020222022202220222022202240404040404040329.645329.645439.840439.840212.521141.392105.969105.969141.392141.39267.606135.58490.20667.60667.60690.20690.2062.0964.2042.7972.0962.0962.7972.797350550750950350550750950350550750950350550750950171.349630.3551060.3551380.1601810.160150.961417.479488.608854.0311284.0311678.6082108.608182.394494.416539.794892.3941322.3941729.7942159.794247.904625.796627.203957.9041387.9041817.2032247.203989.8611036.9391119.362鋼鋼束徑z2(mm)z1(mm)x3(mm)x2(mm)x1(mm)號(hào)z(mm))4712000022903.04643.9542115.489349.04816825.463265420000379048.719216.2813093.2861395.12914801.5850.32000022900.2742237.641104.71916947.640231320000379027.409203.5913266.9991046.71914976.282精選范本表16851.64414976.28216476.28214976.2822141.6613266.9991766.9993266.999296.6951046.7191046.7191046.71920.799169.59169.591135.5912.20127.40927.40927.4092000020000200002000022903790229037900.85333束長度計(jì)算靠近錨固端靠近錨固端直線段長度373.93603.221081.261361.641600.651825.58鋼束長度4008.514012.484011.114011.044011.804015.974016.983643344直線長度1714.051452.591222.62770.72490.72227.6252.06有效長度3858.513862.483861.113861.043861.803865.973866.9841.8978.5478.5455.85鋼束預(yù)80008000鋼束號(hào)五、截面幾何特性計(jì)算1計(jì)算毛截面的截面特性利用CAD軟件計(jì)算控制截面的毛截面截面特性面域精選范本周長：邊界框：質(zhì)心：慣性矩：慣性積：旋轉(zhuǎn)半徑：431.0627Y:0.0000--32.0000X:63.0000X:530765.5136Y:5077713.2348XY:1287605.8477X:22.4792Y:69.5287主力矩與質(zhì)心的X-Y方向：I:133075.6854沿[1.0J:908814.0038沿[0.00001.0000]對(duì)距支座6.25m,1.982m,1.25m變截面，以及跨中截面進(jìn)行相似計(jì)算2、計(jì)算毛截面各分塊的截面特性利用CAD軟件計(jì)算控制截面的毛截面各分塊的截面特性。①上翼緣部分（包括上翼緣板和上承托），15,31.■I精選范本執(zhí)行操作后，可得到如下結(jié)果:----------面域面積：周長：邊界框：質(zhì)心：慣性矩：慣性積：旋轉(zhuǎn)半徑：主力矩與質(zhì)心的X-Y509.3400258.5557Y：0.0000--6.9000Y：4.1535X：9990.2376Y：2630809.6982X：4.4288Y：71.8689方向：I：1203.2504沿[1.00000.0000]用于計(jì)算的CAD面域圖如下:執(zhí)行操作后，可得到如下結(jié)果:精選范本面域面積:217.4922邊界框:X:0.0000--58.2776Y:0.0000--6.0000質(zhì)心:X:29.1388Y:2.1219慣性矩:Y:259909.1644慣性積:XY:13447.4210旋轉(zhuǎn)半徑:X:2.5731Y:34.5692X-Y方向:主力矩與質(zhì)心的I:460.7892沿[1.00000.000J:75243.0610沿[0.00001.0000]對(duì)1/4L截面，距支座6.25m，1.982m，1.25m的變截面進(jìn)行類似計(jì)算3、計(jì)算各控制截面的幾何特性由于本橋采用滿堂支架現(xiàn)澆施工，所以在本設(shè)計(jì)中，需要計(jì)算傳力錨固（預(yù)加應(yīng)力）階段和使用荷載作用階段（運(yùn)營階段）的截面應(yīng)力，以考察箱梁在彈性階段的工作狀態(tài)是否正常。按《鐵路橋規(guī)》第6.3.1條的規(guī)定，計(jì)算預(yù)應(yīng)力混凝土結(jié)構(gòu)截面應(yīng)力時(shí)，對(duì)于后張法結(jié)構(gòu)，在鋼筋管道內(nèi)壓注水泥漿以前，應(yīng)采用被管道削弱的靜混凝土并計(jì)入非預(yù)應(yīng)力鋼筋后的換算截面（即凈截面注：對(duì)于配置較少非預(yù)應(yīng)力鋼筋的構(gòu)件（一般指不允許出現(xiàn)拉應(yīng)力的構(gòu)件）計(jì)算換算截面時(shí)，可不考慮非預(yù)應(yīng)力鋼筋）；在建立了鋼筋與混凝土間的粘結(jié)力后，則采用全部換算截面（但對(duì)受拉構(gòu)件、受彎及大偏心受壓構(gòu)件中運(yùn)營荷載作用時(shí)的受拉區(qū)，不計(jì)管道部分）。所以，對(duì)預(yù)加應(yīng)力階段，作用有預(yù)壓力和梁自重，因還未精選范本壓漿，受力構(gòu)件按凈截面計(jì)算；對(duì)運(yùn)營階段，作用有梁自重、預(yù)應(yīng)力、二期恒載和活載，受力構(gòu)件按成橋后的換算截面計(jì)算(計(jì)管道部分，截面全截面受壓)(1)截面面積及慣性矩計(jì)算采用前面已經(jīng)計(jì)算得到的換算截面來近似計(jì)算截面面積和慣性矩。凈截面面積AjAA△A――管道總面積(成孔總面積);y――分塊面積重心到主梁上緣的距離。計(jì)算中，成孔面積A1010.622011.6229yos換算截面重心到主梁上緣的距離;p――預(yù)應(yīng)力鋼筋彈性模量與混凝土彈性模量之比，即nPp根據(jù)以上計(jì)算方法，可計(jì)算各截面的截面特性。(2)截面靜距計(jì)算E pEc預(yù)應(yīng)力鋼筋混凝土在預(yù)加應(yīng)力階段和運(yùn)營階段都要產(chǎn)生剪應(yīng)力，這兩個(gè)階段的剪應(yīng)力應(yīng)該疊加。在每精選范本一階段中，凡是中心軸位置和截面突變處的剪應(yīng)力，都需要計(jì)算。在傳力錨固階段和運(yùn)營階段應(yīng)計(jì)算的截面為（如圖支點(diǎn)截面及變截面①在傳力錨固階段，凈截面的中性軸（稱凈軸）位置產(chǎn)生的最大剪應(yīng)力，應(yīng)該與運(yùn)營階段在凈軸位置產(chǎn)生的剪應(yīng)②在運(yùn)營階段，換算截面的中性軸（稱換軸）位置產(chǎn)生的最大剪應(yīng)力，應(yīng)該與傳力錨固階段在換軸位置產(chǎn)生的剪應(yīng)力疊加。故對(duì)每一個(gè)荷載作用階段，需要計(jì)算四個(gè)位置的剪應(yīng)力，即需計(jì)算下面幾種情況的靜距:aa-a線以上（或以下）的面積對(duì)中性軸（凈軸和換軸）的靜距；b.b-b線以上（或以下）的面積對(duì)中性軸（凈軸和換軸）的靜距；c?凈軸（j-j）以上（或以下）的面積對(duì)中性軸（凈軸和換軸）的靜距；d?換軸（0-0）以上（或以下）的面積對(duì)中性軸（凈軸和換軸）的靜距；根據(jù)上述方法可計(jì)算各截面的靜矩。精選范本3）截面幾何特性總表將計(jì)算結(jié)果匯總于下表。精選范本表5-1控制截面幾何特性計(jì)算總表混凝土凈截面混凝土換算截面AjAj jysyjxWjsWjxS凈慣性矩凈軸到截面上緣距離凈軸到截面下緣距離上緣截面抵抗矩凈軸以上部分對(duì)凈軸靜矩SSe下翼緣部分Ao鋼束群重心到凈軸距離Ao換算面積o換算慣性矩oyosyosyox換軸到截面下緣距離上緣上緣上翼緣部分截面抵抗矩W對(duì)換軸靜矩S對(duì)換軸靜矩a-ocm2cm4cmcmcm3cm3cm3cm3cm3cm3cmcm2cm4cmcmcm3cm3cm391134.77102040.371179962oo2.381277943201.77116.06121.58203.94198.4210166436.6210511431.475785955.7836440483.5934512725.024897989.884636104.075110840.204631230.725107027.843591401.913746015.22160.36134.0696772.77107678.371316848904.971374457041.71125.42128.61194.58191.3910499661.3910686771.46767586.0777181556.6324512725.025266874.25距支座6.25m106358.801317745410.5110659054.576710415.6265048905.175304343.575301203.463845205.36111996.801395274367.6410759070.037331338.6645370073.3216333087597623706646566452517541675119164664599精選范本凈軸以上部分cm35075359.935536696.945682154.6069160換軸以上部分cm35166443.615540509.315685294.7169174下翼緣部分Sb-0cm34288610.124142927.854136130.2454180鋼束群重心到換軸距離cm精選范本對(duì)預(yù)應(yīng)力混凝土梁，應(yīng)按破壞階段法進(jìn)行抗彎強(qiáng)度計(jì)算，以保證結(jié)構(gòu)破壞時(shí)有足夠的安全度?？箯潖?qiáng)度計(jì)算包括正截面抗彎強(qiáng)度計(jì)算和斜截面抗彎強(qiáng)度計(jì)算，由于還未進(jìn)行箍筋配筋計(jì)算，此處僅計(jì)算正截面抗彎強(qiáng)度。因跨中截面和四分點(diǎn)截面受外荷載作用的彎矩較大，故檢算這兩個(gè)截面就可保證全梁的正截面抗彎強(qiáng)度。1跨中正截面強(qiáng)度計(jì)算由“五、截面特性計(jì)算”的計(jì)算知，上翼緣部分的面積為ffAo50934.0040.424cm，計(jì)算時(shí)取hf=40.4cm。A50934cm2。此時(shí)，等效截面的梁高取為h=314.2cm,較實(shí)際梁高3.2m是偏于安全的。等效截面如下圖：■.■.因本梁采用全預(yù)應(yīng)力，未配置非預(yù)應(yīng)力鋼筋作為受力主筋，故不容許截面上下翼緣出現(xiàn)拉應(yīng)力。根據(jù)《鐵路橋規(guī)》第623條中關(guān)于翼緣處于受壓區(qū)的工字形截面受彎精選范本構(gòu)件的計(jì)算規(guī)定，可有:假定受壓區(qū)高度為X,貝C50混凝土軸心抗壓極限強(qiáng)度fc33.5MPa,預(yù)應(yīng)力鋼絞線抗拉計(jì)算強(qiáng)度fp0.9fpk0.918601674MPa，跨中預(yù)應(yīng)力鋼絞線面積Ap42014058800mm2，上翼緣的平均厚度是hf404mm，有效寬度是bf12600mm，預(yù)應(yīng)力筋重心到梁底的距離為ap435.714mm，計(jì)算高度h0hap3142435.714fcbf'hf'33.512600404故，該截面屬于第一類截面計(jì)算ffcbf'233.194mm0.4hp0.42706.2861082mmMuX故，跨中正截面強(qiáng)度符合要求2、四分點(diǎn)正截面強(qiáng)度計(jì)算(1)等效截面計(jì)算:A52425A52425cm2精選范本ffo52041.607cm，計(jì)算時(shí)取hf=41.6cm。h=314.2cmh=314.2cm,較實(shí)際梁高3.2m是偏于安全的。等效截面如下圖:-^3—9-fllF40—0 ― 9-亞出加出撲假定受壓區(qū)高度為x,貝U:上翼緣的平均厚度是hf416mm，有效寬度是bf12600mm,預(yù)應(yīng)力筋重心到梁底的距離為a643.610mm，pfpApfcbf'hf'f故，該截面屬于第一類f精選范本A233.194mm0.4hp0.42706.2861082mmMu22故，四分點(diǎn)正截面強(qiáng)度符合要求。綜上，預(yù)應(yīng)力構(gòu)件正截面抗彎強(qiáng)度滿足規(guī)范規(guī)定七、預(yù)應(yīng)力損失與有效預(yù)應(yīng)力計(jì)算預(yù)加應(yīng)力是鋼束控制應(yīng)力GCon,根據(jù)《鐵路橋規(guī)》第6.4.1條的規(guī)定，在預(yù)加應(yīng)力的過程中，對(duì)鋼絞線，其錨下控制應(yīng)力值應(yīng)符合下式條件：Ccon=0p+0L<0.75pk。所以,取c8on=0.69fpk=0.69X1860=1283.4MP。2、預(yù)應(yīng)力損失計(jì)算(1)鋼絲束與管道間摩擦引起的預(yù)應(yīng)力損失(T1張拉時(shí)，由于鋼筋與管道間的摩擦引起的應(yīng)力損失按下式計(jì)算：式中卩——鋼筋與管道壁之間的摩擦系數(shù)，取卩=0.2;9――從張拉端至計(jì)算截面的長度上，鋼筋彎起角之和(rad);k——考慮每米管道對(duì)其設(shè)計(jì)位置的偏差系數(shù)，取k=0.0015;x――從張拉端至計(jì)算截面的管道長度(m)。布置在底板內(nèi)的預(yù)應(yīng)力束只有豎彎，9是鋼束在豎平面內(nèi)曲線管道部分的夾角之和，按絕對(duì)值相加；而布置在腹板內(nèi)的預(yù)應(yīng)力束不僅有豎彎也有平彎，9應(yīng)為雙向彎曲精選范本因此可計(jì)算各控制截面的預(yù)應(yīng)力損失,其計(jì)算結(jié)果列于表7-1。精選范本(2)錨頭變形、鋼筋回縮引起的預(yù)應(yīng)力損失(T2由于錨頭變形、鋼筋回縮引起的預(yù)應(yīng)力損失按下式計(jì)算:Ep△L――錨頭變形，鋼筋回縮，接縫壓縮值，查《鐵路橋規(guī)》表634-2對(duì)后張法預(yù)應(yīng)力混凝土梁，當(dāng)計(jì)算由于錨具變形、鋼筋回縮等引起的應(yīng)力損失時(shí),可考慮與張拉鋼筋時(shí)管道間摩擦方向相反的摩擦作用。計(jì)算反向摩阻時(shí)，管道摩擦系數(shù)和偏差系數(shù)可近似采用計(jì)算正向摩阻時(shí)所用值。對(duì)于兩端張拉且對(duì)稱布置的預(yù)應(yīng)力筋，考慮反向摩阻后，錨下預(yù)應(yīng)力筋的應(yīng)力及應(yīng)力不動(dòng)點(diǎn)(錨具、鋼筋回縮引起的應(yīng)力損失為零的點(diǎn))的位置和應(yīng)力可按下列公式試算確定:ilI」鏈：圖中為輻離尉稱納①當(dāng)Xi<lm<X2時(shí),Im精選范本②當(dāng)X2<lm<l/2時(shí),mm>l/2時(shí)，表明應(yīng)力不動(dòng)點(diǎn)不存在，此時(shí)0￡22klT(l甘甘Xi)Xi)]rX2rlll式中，△l---------錨具變形及鋼筋回縮值m）,對(duì)無頂壓的夾片式錨，取△l=6mm；%n――錨下張拉控制應(yīng)力（MPa）;(?――錨下預(yù)應(yīng)力筋的應(yīng)力（MPa）;E――預(yù)應(yīng)力筋彈性模量（MPa）;pk-------每米管道偏差系數(shù)。因此可計(jì)算各控制截面的預(yù)應(yīng)力損失（3）混凝土彈性壓縮引起的預(yù)應(yīng)力損失?4在后張法結(jié)構(gòu)中，當(dāng)分批張拉預(yù)應(yīng)力鋼筋時(shí)，對(duì)先張拉的鋼筋應(yīng)考慮由于混凝土的彈性壓縮引起的應(yīng)力損失，按下式計(jì)算：△?――在先行張拉的預(yù)應(yīng)力鋼筋重心處，由于后來張拉一根鋼筋而產(chǎn)生的混凝土正應(yīng)力（MPa）。精選范本△應(yīng)計(jì)為簡化計(jì)算，對(duì)于簡支梁，可以1/4跨度處的截面為準(zhǔn)求算沿梁長的平均△應(yīng)計(jì)算時(shí)，應(yīng)認(rèn)為CL1和（L2已經(jīng)發(fā)生。工西按下式計(jì)算:N 0api和表4-3。本梁采用分批張拉鋼束，張拉時(shí)按鋼束B1（6束）—B2（4束）—B2'（4束）一F1,F2（4束）—F3,F4（4束）一F5,F6（4束）—F7,F8（4束）的順序，計(jì)算時(shí)應(yīng)從最后張拉的鋼束逐步向因此可計(jì)算各控制截面的預(yù)應(yīng)力損失L4，其計(jì)算結(jié)果列于7-1。對(duì)預(yù)應(yīng)力鋼筋，僅在CCon>0.5$k的情況下，才考慮由于鋼筋松弛引起的與應(yīng)力損失,Z――松弛系數(shù)。對(duì)鋼絞線，低松弛時(shí)，當(dāng)Gcon<0.7pk時(shí)，（5（5）混凝土收縮和徐變引起的應(yīng)力損失6由于混凝土收縮、徐變引起的應(yīng)力損失終極值按下列公式計(jì)算：E0.8npcopAA2A精選范本i式中0——傳力錨固時(shí)，在計(jì)算截面上預(yù)應(yīng)力鋼筋重心處，由于預(yù)加力（扣除相應(yīng)階段的應(yīng)力損失）和梁自重產(chǎn)生的混凝土正應(yīng)力：對(duì)簡支梁可取跨中與跨度1/4截面——混凝土徐變系數(shù)的終極值；——混凝土收縮應(yīng)變的終極值；A――梁截面面積，對(duì)后張法構(gòu)件，可近似按凈截面計(jì)算（m2）;怎一一預(yù)應(yīng)力鋼筋與非預(yù)應(yīng)力鋼筋重心至梁截面重心軸的距離（mI――截面慣性矩，對(duì)于后張法構(gòu)件，可近似按凈截面計(jì)算（m4）。2A29113477對(duì)本梁，由構(gòu)件理論厚度10609.04mm600mm（A為跨中凈u2992.722截面面積，是最小凈截面），又混凝土齡期為14天時(shí)預(yù)加應(yīng)力，則查表6.3.4-3得：則可以計(jì)算混凝土收縮和徐變引起的預(yù)應(yīng)力損失L6,其計(jì)算結(jié)果列于7-1o3、預(yù)應(yīng)力損失匯總及有效預(yù)應(yīng)力計(jì)算對(duì)于后張法構(gòu)件，傳力錨固時(shí)，由于管道摩擦，錨固變形、鋼筋回縮和混凝土彈性壓縮引起的預(yù)應(yīng)力損失已經(jīng)完成。故，此階段發(fā)生的預(yù)應(yīng)力損失G=C1+現(xiàn)2+OL4精選范本(2)張拉后二天,張拉后兩天，由于鋼筋松弛產(chǎn)生的預(yù)應(yīng)力損失已經(jīng)完成了失。所以，此階段發(fā)生的預(yù)應(yīng)力損失(LI=0.5L5@(3)全部損失完后,從張拉后二天至預(yù)應(yīng)力全部損失完后，發(fā)生的預(yù)應(yīng)力損失為有效預(yù)應(yīng)力有效預(yù)應(yīng)力50%,應(yīng)減去這部分損表7-1鋼束預(yù)應(yīng)力損失匯總表預(yù)應(yīng)力損失項(xiàng)鋼傳力錨固時(shí)張拉后兩天全部損失完后跨中距支座6.25mC(MPa)49.59162.44453.89160.29556.66462.11666.69931.64944.68936.01125.29638.402C(MPa)84.818102.51584.32171.93568.03565.47461.833103.347121.044102.85090.46486.56484.00380.362109.844127.541109.34896.961C(MPa)105.69290.04264.56543.13125.4260.00083.18969.20745.96126.8176.0610.00073.23659.40636.38521.334C(MPa)7.9446.8019.6808.34720.2659.1056(MPa)71.28570.53072.785鋼束應(yīng)力p01043.2991028.3981080.6231108.0391133.2761144.6041154.8681065.2151048.4601098.5771147.6481163.2651174.8641184.5661075.0231058.0501120.9961153.054鋼束應(yīng)力p11039.3271024.9981075.1541101.4101125.5351136.3501146.1421060.3751044.2861092.3541139.2551154.1471165.1971174.4331069.7851053.4981113.8011144.411鋼束有效應(yīng)力964.070950.313998.3991023.4971046.5091056.8111066.131985.005969.5831015.6011060.3311074.4991085.0011093.770991.761976.1601033.8221062.984精選范本距支座1.982m距支座支座3.8873.8873.8873.8873.8873.8872.4812.4812.4812.4812.4812.4812.4810.0770.0770.0770.0770.0770.0770.07793.06190.50086.860118.061135.758117.564105.177101.27798.71795.076119.470137.167118.973106.586102.686100.12696.485121.876139.573121.379108.993105.093102.53298.8915.2240.00042.81933.77121.7928.3684.4160.00035.77928.4407.4864.1280.00030.97425.0157.2264.1830.00020.25820.25320.25320.25265.38261.05359.7121166.3041175.6241184.4891109.3461109.9851140.1581160.7641169.8681176.3811184.4381125.6701115.3121143.4451162.5951170.7461176.6651184.4341130.4731118.7351145.3941163.5241171.0041176.6081184.4321157.0431165.9211174.3601102.6611103.2711132.1061151.7631160.4381166.6421174.3111118.2691108.3671135.2441153.5091161.2751166.9121174.3081122.8581111.6401137.1041154.3941161.5211166.8581174.3051074.9971083.4331091.4461030.5941031.1771058.6731077.3811085.6281091.5211098.8031049.8141040.3681065.9901083.3691090.7511096.1061103.1281055.5301044.8331069.1021085.5521092.3261097.3961104.4674、預(yù)加力計(jì)算剪力QA-預(yù)應(yīng)力彎起鋼筋的切線與構(gòu)件縱軸間的夾角精選范本Api——鋼束的面積，如對(duì)鋼束B1,APBI=6X12X140=10080mmepi鋼束重心至截面重心的距表7-2傳力錨固時(shí)預(yù)加力作用效應(yīng)計(jì)算表截面跨中距支座6.25m鋼束號(hào)藝藝0.00000.00000.00000.00000.00000.00000.00000.00000.00000.00000.05230.05230.06980.06980.00000.00000.01650.05230.0523COSa0.99860.99860.99760.99760.99990.99860.9986(kN)10516.4516910.8369077.2339307.5309519.5189614.6719700.89010737.3677045.6499228.0509640.2419771.4289868.8589950.35310836.2347110.0989416.3629685.6519796.954p0cpoip(kN)10516.4516910.8369077.2339307.5309519.5189614.6719700.89064647.12910737.3677045.6499228.0509627.0299758.0379844.8189926.11466167.06510836.2347110.0989415.0889672.3779783.5280.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000504.531511.397688.417694.1022398.4470.0000.000154.935506.908512.733M(kN.m)19869.31413057.02517150.11915723.72514177.94612396.72710567.717102942.57319694.85312923.37616926.41114736.63310741.2188270.4104070.47687363.37719654.01812895.80816875.44212896.9198838.208精選范本距支座1.982m距支座支座藝藝藝0.06980.06980.03690.10450.06980.05230.05230.06980.06980.05230.10450.06980.05230.05230.06980.06980.05230.10450.06980.05230.05230.06980.06980.99760.99760.99930.99450.99760.99860.99860.99760.99760.99860.99450.99760.99860.99860.99760.99760.99860.99450.99760.99860.99860.99760.99769875.2419949.70411182.2127459.0969577.3269750.4209826.8889881.5999949.27511346.7557494.8949604.9399765.7989834.2679883.9889949.24611395.1667517.9009621.3119773.6059836.4339883.5079949.2269851.1869925.46766593.97711174.6177418.2349553.9969737.0579813.4219857.5279925.03967479.89111331.2057453.8369581.5429752.4159820.7909859.9119925.01067724.70811379.5497476.7169597.8749760.2109822.9539859.4329924.99067821.723688.862694.0562557.494412.075779.688668.080510.298514.300689.305694.0264267.772593.843783.430670.007511.102514.686689.472694.0244456.564596.377785.835671.149511.511514.799689.439694.0234463.1325748.8671524.26578433.52819148.77710734.76113145.8109839.5445696.9411832.997-2422.21657976.61318670.7649956.15012363.3459145.1294986.307989.238-3271.98552838.94817855.0328905.91611419.0368384.4664214.495-2.500-4270.26346506.182(2)張拉后二天,計(jì)算方法同上，此時(shí)用于計(jì)算的鋼束應(yīng)力為0表7-3張拉后二天預(yù)加力作用效應(yīng)計(jì)算表精選范本截面跨中距支座6.25m距支座1.982m鋼束號(hào)藝藝藝0.00001.00000.00001.00000.00001.00000.00001.00000.00001.00000.00001.00000.00001.00000.00001.00000.00001.00000.00001.00000.05230.99860.05230.99860.06980.99760.06980.99760.00001.00000.00001.00000.01650.99990.05230.99860.05230.99860.06980.99760.06980.99760.03690.99930.10450.99450.06980.99760.05230.99860.05230.9986ACp1ipi(kN)10476.4146887.9869031.2919251.8479454.4959545.3389627.59010688.5827017.6049175.7779569.7389694.8389787.6579865.23810783.4287079.5059355.9299613.0569719.1639793.7369864.62011114.8237413.9849509.6939674.8139747.683p0cp1ipi10476.4146887.9869031.2919251.8479454.4959545.3389627.59064274.96110688.5827017.6049175.7779556.6239681.5519763.8159841.20765725.15910783.4287079.5059354.6639599.8829705.8439769.8799840.59166133.79111107.2747373.3709486.5289661.5549734.324Qpo=c1iApiSina(kN)0.0000.0000.0000.0000.0000.0000.0000.0000.0000.0000.000500.841507.389682.752688.1642379.1470.0000.000153.940503.108508.662683.176688.1212537.008409.591774.972663.363506.341510.154M18813.73012369.56716218.55314764.26213196.75211414.4859587.32596364.67418853.27612378.14616184.88413956.4149975.7917515.3383343.18982207.03718905.12412411.53716200.55512218.8218180.1775109.687915.21673941.11618625.16110398.85112704.3269408.1625293.264精選范本距支座支座藝藝0.06980.06980.05230.10450.06980.05230.05230.06980.06980.05230.10450.06980.05230.05230.06980.0698全部損失完成后,0.99760.99760.99860.99450.99760.99860.99860.99760.99760.99860.99450.99760.99860.99860.99760.99769799.7909864.21211272.1517448.2249536.0519689.4729754.7129802.0649864.18411318.4047470.2229551.6759696.9129756.7759801.6079864.1659775.9189840.18466979.15111256.7037407.4229512.8219676.1939741.3449778.1879840.15667212.82511302.8937429.2999528.4079683.6239743.4049777.7319840.13767305.493683.599688.0934236.113589.939778.551665.201507.108510.522683.757688.0914423.170592.360780.851666.291507.497510.630683.726688.0894429.4441458.534-2763.15655125.14218209.0969671.13711988.2678782.3304652.685686.644-3540.27150449.89017447.9258660.90511094.5898072.9363933.110-250.606-4483.46444475.395計(jì)算方法同上，此時(shí)用于計(jì)算的鋼束應(yīng)力為表7-4全部損失完后預(yù)加力作用效應(yīng)計(jì)算表(kN)(kN0.00000.0000跨中0.000017451.44411468.27415060.72613719.83912270.18610615.5289717.8266386.1018386.5568597.3728790.6798877.2129717.8266386.1018386.5568597.3728790.6798877.2120.0000.0000.0000.0000.0000.00000.00000.00000.000精選范本距支座6.25m距支座1.982m距支座藝藝藝藝0.00000.00000.00000.00000.05230.05230.06980.06980.00000.00000.01650.05230.05230.06980.06980.03690.10450.06980.05230.05230.06980.06980.05230.10450.06980.05230.05230.06980.99860.99860.99760.99760.99990.99860.99860.99760.99760.99930.99450.99760.99860.99860.99760.99760.99860.99450.99760.99860.99860.99768955.4979928.8556515.5988531.0528906.7839025.7969114.0059187.6729996.9496559.7978684.1028929.0689029.9789100.8379168.14310388.3886929.5088892.8559050.0019119.2729168.7759229.94410582.1296991.2768954.3139100.2979162.3089207.2928955.49759711.2429928.8556515.5988531.0528894.5779013.4269091.8049165.29161140.6029996.9496559.7978682.9278916.8319017.6039078.6689145.81061398.58410381.3326891.5488871.1929037.5989106.7749146.4409207.46062642.34510567.6266952.9778932.5019087.8259149.7529184.8640.0000.0000.0000.0000.000466.145472.374635.761640.9002215.1790.0000.000142.886467.311472.593634.842639.5372357.170382.822724.331620.334473.640477.266639.581643.8483961.823553.826730.787624.621476.273479.518642.2688918.04289504.03817513.21511492.67115047.67312989.5679287.3616998.0823113.57176442.14017526.29711500.40315037.23211349.4267600.1214748.181850.59868612.25817407.8709719.32511880.2718800.5714952.0201364.618-2585.48651539.18817094.4309077.81311256.9358248.3154370.127644.980精選范本-3325.680-3325.68047366.92016401.7368140.40510431.1017591.5073698.803-235.687-4216.82341811.04110639.7457021.2798980.4579118.6389175.5369218.1269277.52310625.1646982.8168958.5819106.1419162.9619195.6719254.924556.841733.924626.445477.233480.210643.024647.1670.99860.99450.99760.99860.99860.99760.99760.05230.10450.06980.05230.05230.06980.0698藝63119.24763286.2584153.6764164.8449243.7029266.274646.3830.06980.9976支座八、跨中截面抗裂性計(jì)算根據(jù)《鐵路橋規(guī)》第639條的規(guī)定，對(duì)不允許出現(xiàn)拉應(yīng)力的構(gòu)件的正截面，當(dāng)構(gòu)件受彎時(shí)，其抗裂性應(yīng)按下列公式計(jì)算:oof――抗裂安全系數(shù)。當(dāng)主力作用時(shí)，抗裂安全系數(shù)Kf=1.2;c――扣除相應(yīng)階段預(yù)應(yīng)力損失后混凝土的預(yù)壓應(yīng)力；Wo――對(duì)所檢算的拉應(yīng)力邊緣的換算截面抵抗距（m3）;S0――換算截面重心軸以下的面積對(duì)重心軸的面積矩（m3）。對(duì)預(yù)應(yīng)力混凝土簡支梁，當(dāng)構(gòu)件破壞時(shí)，跨中正截面最先開裂，即跨中截面是危險(xiǎn)截面，故選作控制截面。按《鐵路橋規(guī)》第6.3.1條的規(guī)定，檢算正截面抗裂性時(shí)，在建立了鋼筋與混凝土精選范本間的粘結(jié)力后，應(yīng)采用全部換算截面，但對(duì)受拉構(gòu)件運(yùn)營荷載作用時(shí)的受拉區(qū)，不計(jì)面積Aj=91134.77crm慣性矩lj=1179962002.38cm截面重心至梁底的距離y=203.94cm不計(jì)管道部分的換算截面：面積A0珞人npAp94130.912996截面重心軸至梁底的距離y198.45cm37152.41(198.4566.00)2996.14(198.4543.22)3229.86(198.4543.57)4955705.38cm348355.271179962.00238203.94M35354.29+33728.951260180.18154Mjyojyo.預(yù)加應(yīng)力作用下,精選范本跨中截面下緣混凝土中產(chǎn)生的正應(yīng)力為:pi64274.999113.47722.14MPaIjA096364.721179962.00238M p4563.726860.639436.4631260180.18154考慮混凝土塑性的修正系數(shù)：2SW2Sc4955705.3801260180181.540KK故，跨中截面抗裂性滿足規(guī)范要求。九、預(yù)加應(yīng)力階段的計(jì)算1、傳力錨固時(shí)預(yù)應(yīng)力鋼束應(yīng)力的檢算按《鐵路橋規(guī)》第6.4.3條規(guī)定，在傳力錨固時(shí)，預(yù)應(yīng)力鋼筋的應(yīng)力應(yīng)符合下列條由表7-8知，傳力錨固時(shí)，預(yù)應(yīng)力鋼束最大應(yīng)故，滿足規(guī)范要求。2、預(yù)加應(yīng)力階段的檢算按《鐵路橋規(guī)》第6.4.4條規(guī)定，在存梁階段，計(jì)入構(gòu)件自重作用后，混凝土的正精選范本應(yīng)力應(yīng)符合下列條件：當(dāng)構(gòu)件全截面受壓時(shí),O精選范本對(duì)C50混凝土，系數(shù)a=0.75，混凝土的抗壓極限強(qiáng)度fC33.5MPa(1)預(yù)加應(yīng)力階段預(yù)應(yīng)力在截面上下邊緣產(chǎn)生的混凝土正應(yīng)力預(yù)加應(yīng)力階段預(yù)應(yīng)力在截面上下邊緣產(chǎn)生的混凝土正應(yīng)力應(yīng)按下式計(jì)算: 式中，――預(yù)加應(yīng)力階段由預(yù)應(yīng)力在截面上下邊緣產(chǎn)生的混凝土應(yīng)力(以壓為正)；pi、Mpi――預(yù)加應(yīng)力階段由預(yù)應(yīng)力鋼束產(chǎn)生的軸向力、彎矩;(2)梁自重在上下邊緣產(chǎn)生的混凝土正應(yīng)力預(yù)加應(yīng)力階段梁自重在上下邊緣產(chǎn)生的混凝土正應(yīng)力應(yīng)按下式計(jì)算:M j式中，OC2――預(yù)加應(yīng)力階段由自重在截面上下邊緣產(chǎn)生的混凝土應(yīng)力(以壓為正)Mgi――預(yù)加應(yīng)力階段由自重產(chǎn)生的彎矩(3)由預(yù)應(yīng)力及自重產(chǎn)生的混凝土正應(yīng)力由預(yù)應(yīng)力及自重產(chǎn)生的混凝土正應(yīng)力應(yīng)按下式計(jì)算:f0.733.523.45MPaf0.733.523.45MPa根據(jù)以上公式的正截面混凝土壓應(yīng)力驗(yàn)算的計(jì)算過程和結(jié)果見表i5表9-i傳力錨固階段正截面混凝土壓應(yīng)力計(jì)算表變截面67724.7i6782i.7252838.9546506.i8跨中截面64647.i3i02942.5766i67.0787363.3867479.8957976.6i66593.9878433.53距支座6.25m變截面變截面精選范本1179962002.38116.06203.9448355.277.09-10.13-3.034.767.0924.89-8.361277943201.7730303.966.48-8.31-1.832.886.4820.05-4.711317745410.5127674.894386.26-7.36-1.102.606.26-4.12j(cm4)Np0Aj(MPa)j)/Ij5.22-4.740.480.865.226.62-1.196781.120.004.714.714.514.510.6010.200.969.180.53-0.700.000.001.139.500.969.18129282.511633302005.0410463.42143793.701760914567.57150397.051809574814.5091134.77102040.37106358.80-4.115.49-3.554.67由上表的計(jì)算過程及計(jì)算結(jié)果可以看出，在存梁階段，混凝土的最大壓應(yīng)力在跨中截面下緣處，其值為16.53MPa小于23.45MPa符合規(guī)范規(guī)定十、運(yùn)營階段計(jì)算1、運(yùn)營荷載作用下混凝土正應(yīng)力的檢算按《鐵路橋規(guī)》第6.3.10條的規(guī)定，在運(yùn)營荷載作用下，正截面混凝土壓應(yīng)力（扣，％營荷載及預(yù)應(yīng)力鋼筋有效預(yù)應(yīng)力產(chǎn)生的正截面混凝土最大壓應(yīng)力（MPa按《鐵路橋規(guī)》第6.3.10條的規(guī)定，在運(yùn)營荷載作用下，正截面混凝土受拉區(qū)應(yīng)力（扣除全部應(yīng)力損失后）應(yīng)符合下列規(guī)定：對(duì)不允許出現(xiàn)拉應(yīng)力的構(gòu)件，中，@是運(yùn)營荷載及預(yù)應(yīng)力鋼筋有效預(yù)應(yīng)力在混凝土截面受拉邊緣產(chǎn)生的應(yīng)力（MPa（1）有效預(yù)應(yīng)力產(chǎn)生的混凝土正應(yīng)力運(yùn)營階段預(yù)應(yīng)力在截面上下邊緣產(chǎn)生的混凝土正應(yīng)力應(yīng)按下式計(jì)算:/N/Npp式中，問，甸一一運(yùn)營階段由預(yù)應(yīng)力在截面受壓區(qū)、受拉區(qū)產(chǎn)生的混凝土正應(yīng)力(Mpy。)精選范本pi,Mpi――預(yù)應(yīng)力筋張拉后兩天由于預(yù)應(yīng)力在構(gòu)件正截面上產(chǎn)生的軸向力、彎矩（計(jì)算時(shí)，認(rèn)為張拉預(yù)應(yīng)力鋼筋后兩天才壓漿封錨）；△N，A――從張拉后兩天至完成損失全部時(shí)，這部分損失的預(yù)A,I（2）由自重、道砟及活載在截面產(chǎn)生的混凝土正應(yīng)力運(yùn)營階段由自重、道砟及活載在上下邊緣產(chǎn)生的混凝土正應(yīng)力應(yīng)按下式計(jì)算：，％Ct2――運(yùn)營階段由自重、道砟及活載在截面截面受壓區(qū)、受拉區(qū)產(chǎn)生的混凝活M活（3）由自重、道砟、活載及有效預(yù)應(yīng)力共同產(chǎn)生的混凝土應(yīng)力gi活0-yjIy0MPa0根據(jù)以上公式的正截面混凝土壓應(yīng)力驗(yàn)算的計(jì)算過程和結(jié)果見表10-1表10-1運(yùn)營荷載作用下正截面混凝土壓應(yīng)力計(jì)算表變截面67212.8367305.4950449.8944475.39變截面變截面跨中截面64274.9696364.67（kN）66979.1555125.1466133.7973941.1265725.1682207.04精選范本j(cm4)o(cm4)(MPa)(Mg1-yj)/Ij(MPa)ANp/A0(MPa)(MPa)(Mg2+M活)-(y0/I0)59711.2489504.0491134.771179962002.38116.06203.9496772.771316848904.9748355.2735814.8733728.954563.726860.647.05-9.484.760.47-0.657.05-8.360.476.58-10.2161140.6076442.14102040.371277943201.77107678.371374457041.7137019.2526861.1525307.194584.565764.906.44-7.823.520.43-0.546.44-5.750.430.804.85-7.2261398.5868612.26106358.801317745410.51111996.801395274367.6427674.8919481.0218409.534735.215328.866.22-6.942.600.42-0.506.22-4.120.420.733.50-5.1362642.3451539.19129282.511633302005.04134920.511675116073.6010463.426995.406727.284336.813585.955.18-4.510.860.32-0.295.186.29-1.190.