【正文】
由上表可見,組合10產(chǎn)生的內(nèi)力最大,控制設(shè)計(jì)。恒載加活載作用下各截面的內(nèi)力(1)彎矩計(jì)算:截面位子見圖示。為求得彎矩最大值,支點(diǎn)負(fù)彎矩取用非對稱布置時(shí)數(shù)值,跨中的彎矩取用對稱布置時(shí)數(shù)值。按下圖給出的截面位置,各截面彎矩計(jì)算(按最大荷載布置):M=0M==;M==M=+=M=+=上面的彎矩計(jì)算均未考慮施工荷載的影響。各截面的相應(yīng)最大彎矩時(shí)剪力計(jì)算如下:截面:Q左=0,Q右 =R1=截面:Q左= Q右 =R1=截面:Q左=R1=, Q右 =G1R1==;截面:Q左=R1,=,Q右 = G1R1R2==;截面:Q左= G1R1R2=;Q右 = G1R1R2R3==蓋梁內(nèi)力匯總表蓋梁內(nèi)力匯總表內(nèi)力1122334455彎矩(KN*m)自重荷載0總合剪力(KN)自重1800荷載總合 采用25號混凝土,主筋用16錳鋼,保護(hù)層用5㎝(鋼筋支混凝土邊緣)。查“橋規(guī)”得到[]=11000kPa,[]=185000kPa. 彎矩作用時(shí)配筋計(jì)算各截面所需鋼筋量,見下表。配筋圖如下各截面鋼筋量計(jì)算表 截面號M總bh.ruA(cm2)鋼筋數(shù) 112221063233207624425516342 建立作用時(shí)配筋計(jì)算(1) 各截面主拉應(yīng)力計(jì)算,在蓋梁懸臂部分變高度區(qū)間主拉應(yīng)力的計(jì)算公式為: 其它等高區(qū)間用計(jì)算式為: 具體計(jì)算表如下,查橋規(guī),25號混凝土容許主拉應(yīng)力值為: (2) 斜筋、箍筋的配置。由于各截面的主拉應(yīng)力墩柱直徑為150㎝,用20號混凝土,I級鋼筋。如于該橋很長墩柱很多,而各處水深差別很大,故不同橋墩的高差很大,最小處不足10 m,最大處超過20 m,但是無論長短,不影響垂直應(yīng)力的布置,在考慮彎矩作用時(shí),墩柱越長受力越大,所以,取最大的墩柱長進(jìn)行設(shè)計(jì)。恒載計(jì)算:(1)上部構(gòu)造恒載,;(2)蓋梁自重,;(3)墩柱自重,21=。作用于墩柱底面的恒載垂直力為:N恒=++=?;钶d計(jì)算:荷載布置如前所述活載中雙孔荷載產(chǎn)生支點(diǎn)處最大反力值,即產(chǎn)生最大墩柱垂直力?;钶d中單孔荷載產(chǎn)生最大偏心彎矩,即產(chǎn)生最大墩柱低彎矩。 雙柱反力橫向分布系數(shù)計(jì)算:1) 汽—20:,2) 掛—100:,3) 人群荷載:(1)最大最小垂直反力計(jì)算,見下表荷載組合垂直反力計(jì)算表(雙孔)編號荷載情況最大垂直反力最小垂直反力 B B1汽202掛1003人群荷載 (3) 最大彎矩時(shí)計(jì)算(單孔)荷載組合最大彎矩計(jì)算編號荷載情況柱頂反力水平力對柱頂中心彎矩1汽20單孔2掛100——3人群單孔——表中水平力由兩墩柱均分 作用于墩柱頂?shù)耐饬Γ?)垂直力:Nmax=+=;(2)彎矩:Mmax=++=。(3)水平力:H=.作用于墩柱底的外力Nmax=+=。Nmin=++=。Mmax=+21=截面配筋計(jì)算墩柱選用20號混凝土,查得[]=7000 kN/㎡,鋼筋選用。由于l/d=21/2=7,偏心矩的增大系數(shù):=。(1)雙孔荷載,最大垂直反力時(shí),墩柱按軸心受壓構(gòu)件驗(yàn)算: = Nmax /(Ah+mAg)式中:Ah ==㎡m——鋼筋屈服強(qiáng)度與混凝土軸心抗壓極限強(qiáng)度的比值,按I鋼筋與20號混凝土可查的:m=17。故 =(+17)=[](2)單孔荷載,最大彎矩時(shí),墩柱按小偏心受壓構(gòu)件計(jì)算e0=M/N=247。=e0’=247。=20號混凝土,按圓型鋼筋混凝土截面桿件強(qiáng)度計(jì)算公式,查表可得: T= S=壓應(yīng)力:=247。(++)=[]拉應(yīng)力:=(-)=-650kPaK=247。(-)=鋼筋應(yīng)力:=-10(-)247。 =-135000kPa混凝土拉應(yīng)力小于容許應(yīng)力,表明墩柱不會出現(xiàn)裂縫,按小偏心構(gòu)件計(jì)算可行。同時(shí)墩柱配筋滿足規(guī)范要求,箍筋和駕立筋可按要求配置。,用20號混凝土,20I及鋼筋。由于該地區(qū)經(jīng)由有關(guān)部門勘測顯示,:工程地質(zhì)條件良好,無不良工程地質(zhì)現(xiàn)象或地段。—,沙礫顆粒較大,地下水較豐富,6米以下為花崗巖層,可做為承載地基,宜設(shè)計(jì)鉆孔灌注樁基礎(chǔ)。首先計(jì)算每根樁承受的垂直荷載Nmax(包括活載) N=+1/2(225)= kN灌注樁每延米自重 q=15=水平荷載:T=(不考慮風(fēng)力、地震力)彎矩M=(1065+)+23= kN*m按已有的地質(zhì)資料,地面以下大約1到6米為圓礫層,再以下均為混合花崗巖層,由于上層很薄且與花崗巖比較差不很大,所以均按花崗巖計(jì)算,并且預(yù)留兩米作為補(bǔ)充。我取樁長為18米,考慮沖刷及補(bǔ)充,最后取20米。檢驗(yàn)裝的承載力: [N]=1/2(17120)+(700+) =所以,選取的裝廠可以滿足垂直承載力的要求。 該樁可按彈性樁計(jì)算,先算樁身的彎矩裝的變形系數(shù):a=,樁的計(jì)算寬度:b=(+)=已知作用于地面處樁頂上的外力,見上頁。樁身在地面以下深度Z處截面上的彎矩MZ與水平力的計(jì)算,見下面兩表:樁身彎矩Mg計(jì)算(單位:kN*m)Z Z*aa*hAmBmHo*Am/aMoBmMg水平壓應(yīng)力計(jì)算(單位:kN/m2) ZZ*aAXBxaHoZAx/ba2MoZB/b00 000234驗(yàn)算最大彎矩值(Z=)處的截面強(qiáng)度,該處內(nèi)力值為:M=*mN=+=該樁的配筋情況為2020,Ag=(㎝2),=%。由上計(jì)算可知:主梁的滿足要求。 第二部分 英文翻譯Reliability analysis :a structures management tool for concrete bridgesReinforced concrete structures are susceptible to a variety of deterioration mechanisms, including alkalithaw action and chloride ingress. Substantial research has been undertaken in relation to these mechanisms and other problems. This has particularly been the case over the last 20 years or so, where the objective has been to identify causes, consequences and develop remediation strategies. This has improved understanding of longterm behaviour of reinforced concrete and resulted in the development of techniques to increase deterioration resistance.At present, the most mon approach is to act after a problem has been identified, known as reactive maintenance. This may not be the most economic solution since, in many cases, maintenance is more costly than preventative treatments. However, owners are often reluctant to pay for preventative treatments before deterioration is apparent. Early application of treatments may not be the optimal solution in the long run. Integrated deterioration and performance prediction modeling is essential to proactively plan and prioritise inspection, testing and maintenance. This bees increasingly important as infrastructure ages and justification for maintenance funding bees increasingly critical. Performance assessment can be achieved through surveys, testing and formal calculations, ideally based on site data that represent, as accurately as possible, the state of the structure. By integrating predictive deterioration models with assessment tools and performance criteria (at element, structure or group level) it bees possible to base the maintenance regime on timedependent performance profiles. This is particularly relevant in the context of wholewife costing procedures.Substantial research has been undertaken in relation to these mechanisms and other problems. This has particularly been the case over the last 20 years or so, where the objective has been to identify causes, consequences and develop remediation strategies. This has improved understanding of longterm behaviour of reinforced concrete and resulted in the development of techniques to increase deterioration resistance.At present, the most mon approach is to act after a problem has been identified, known as reactive maintenance. This may not be the most economic solution since, in many cases, maintenance is more costly than preventative treatments. However, owners are often reluctant to pay for preventative treatments before deterioration is apparent. Early application of treatments may not be the o