雙幅整體澆筑式造橋機(jī)安全性分析與試驗(yàn)

秘嘉川,呂彭民,關(guān)澤強(qiáng),桂發(fā)君,史妍妮

(1.山東恒堃機(jī)械有限公司,濟(jì)南250014; 2.長(zhǎng)安大學(xué) 道路施工技術(shù)與裝備教育部重點(diǎn)實(shí)驗(yàn)室,西安710064)

秘嘉川(1980—),男,工程師.E-mail:77281303@qq.com

呂彭民(1957—),男,教授,博士.E-mail:lpmin@chd.edu.cn

雙幅整體澆筑式造橋機(jī)安全性分析與試驗(yàn)

秘嘉川1,呂彭民2,關(guān)澤強(qiáng)2,桂發(fā)君2,史妍妮2

(1.山東恒堃機(jī)械有限公司,濟(jì)南250014; 2.長(zhǎng)安大學(xué) 道路施工技術(shù)與裝備教育部重點(diǎn)實(shí)驗(yàn)室,西安710064)

以MSS50雙幅整體澆筑式移動(dòng)模架造橋機(jī)作為研究對(duì)象,利用有限元軟件對(duì)該造橋機(jī)整體結(jié)構(gòu)進(jìn)行剛度和強(qiáng)度校核,并依據(jù)計(jì)算結(jié)果,確定了該造橋機(jī)各重要部位的應(yīng)力和變形檢測(cè)位置,在造橋機(jī)使用前進(jìn)行預(yù)壓載試驗(yàn),對(duì)檢測(cè)位置要進(jìn)行全程監(jiān)控.研究結(jié)果表明，理論分析與實(shí)測(cè)結(jié)果基本吻合,該造橋機(jī)滿足強(qiáng)度和剛度要求,實(shí)測(cè)撓度曲線可以為施工中預(yù)拱度調(diào)整提供參考.由于實(shí)際加載過(guò)程中主梁上承受載荷的不均勻性,各測(cè)點(diǎn)應(yīng)力并非按線性規(guī)律變化,甚至出現(xiàn)瞬時(shí)應(yīng)力超過(guò)最大載荷情況下的應(yīng)力,因此，對(duì)加載過(guò)程進(jìn)行監(jiān)控是必要的.由于該雙幅整體澆筑式移動(dòng)模架造橋機(jī)結(jié)構(gòu)龐大,受加工和安裝誤差影響,在加載過(guò)程中左右側(cè)支腿受力出現(xiàn)一定偏差和不均勻性,這在施工過(guò)程中,尤其在有風(fēng)載施工過(guò)程中,應(yīng)加強(qiáng)觀察和檢測(cè).該研究成果也可以為其他移動(dòng)模架設(shè)計(jì)及施工提供參考.

雙幅整體澆筑; 移動(dòng)模架; 有限元分析; 預(yù)壓載試驗(yàn); 預(yù)拱度

移動(dòng)模架造橋機(jī)是當(dāng)今世界上一種先進(jìn)的橋梁施工設(shè)備,在高墩公路橋梁、高架立交橋、高鐵橋梁等建設(shè)中廣泛使用[1].造橋機(jī)屬于大型非標(biāo)結(jié)構(gòu),其安全性要求高,許多專家學(xué)者從不同角度進(jìn)行了分析研究[2-4],但由于造橋機(jī)結(jié)構(gòu)龐大,受力復(fù)雜,仍有造橋機(jī)失事的報(bào)道[5].而MSS50雙幅整體澆筑式移動(dòng)模架造橋機(jī)是一種新型造橋機(jī),該造橋機(jī)可實(shí)現(xiàn)雙幅橋梁一次整體澆筑施工,最大混凝土澆筑方量可達(dá)1 092 m3,最大載荷高達(dá)28 993.6 kN,為目前國(guó)內(nèi)承載力最大、雙幅整體澆筑跨徑最大的設(shè)備.該造橋機(jī)屬于上行式結(jié)構(gòu),主要結(jié)構(gòu)由主梁、鼻梁、上橫梁、下掛梁、前支腿、中支腿、后支腿和模板系統(tǒng)等組成,整體結(jié)構(gòu)如圖1所示.為確保該設(shè)備能達(dá)到施工要求和結(jié)構(gòu)的安全可靠性,本文采用有限元分析軟件,對(duì)該造橋機(jī)的整體結(jié)構(gòu)進(jìn)行強(qiáng)度和剛度計(jì)算分析,并根據(jù)計(jì)算結(jié)果,對(duì)關(guān)鍵應(yīng)力點(diǎn)進(jìn)行應(yīng)力和主梁變形進(jìn)行現(xiàn)場(chǎng)試驗(yàn),為造橋機(jī)的施工安全和預(yù)拱度調(diào)整提供技術(shù)支持.

圖1 MSS50雙幅整體澆筑式造橋機(jī)結(jié)構(gòu)示意圖Fig.1The structure diagram of MSS50 double amplitudeintegrally overhead launching gantry

1 MSS50移動(dòng)模架造橋機(jī)各主要部位有限元計(jì)算分析

1.1主梁和中支腿

造橋機(jī)上部結(jié)構(gòu)有限元模型如圖2(a)所示,主梁、鼻梁和中支腿均采用板殼元,橫梁采用梁?jiǎn)卧?共劃分梁?jiǎn)卧? 404個(gè),板殼元96 712個(gè),節(jié)點(diǎn)94 734個(gè),選取造橋機(jī)最大受力工況(即50 m澆筑)作為計(jì)算工況.計(jì)算結(jié)果為:主梁的Mises應(yīng)力云圖見圖2(b),σmax=223 MPa,位于主梁跨中處;主梁的凈變形圖見圖2(c),主梁50 m跨中處最大凈撓度為72.033 mm;中支腿σmax=217 MPa,位于中支腿下部腹板處.由于主梁和中支腿均采用Q345B材料,其許用應(yīng)力[σ]=230 MPa,故主梁中支腿滿足強(qiáng)度要求.由于主梁撓跨比為

故主梁滿足剛度要求.

圖2 主梁和中支腿計(jì)算模型及計(jì)算結(jié)果Fig.2The calculation model and calculationresults of main girder and middle legs

1.2后支腿

后支腿計(jì)算模型見圖3(a),全部采用板殼元模擬,共劃分板殼元5 553個(gè),節(jié)點(diǎn)5 147個(gè),后支腿承受載荷為9 204.6 kN.計(jì)算結(jié)果如下:Mises應(yīng)力云圖見圖3(b),σmax=212 MPa<[σ],位于后支腿上部支撐位置.故結(jié)構(gòu)滿足強(qiáng)度要求.

1.3橫梁

橫梁分為上橫梁和下掛梁兩部分：上橫梁用梁?jiǎn)卧M,共劃分梁?jiǎn)卧?86個(gè),節(jié)點(diǎn)542個(gè);下掛梁用板殼元模擬,共劃分板殼元7 915個(gè).節(jié)點(diǎn)7 425個(gè).造橋機(jī)在澆筑時(shí),處于墩頂周圍的橫梁承受力較大,本文選取承受力最大的第3根橫梁計(jì)算,其最大載荷為2 312.4 kN.計(jì)算模型分別見圖4(a)和圖4(b).計(jì)算結(jié)果如下:Mises應(yīng)力云圖如圖4(c)和圖4(d)所示,上橫梁σmax=113 MPa<[σ]=157 MPa(材料為Q235B),下掛梁σmax=204 MPa<[σ]=230 MPa(材料為Q345B),故橫梁滿足強(qiáng)度要求.

圖3 后支腿計(jì)算模型與計(jì)算結(jié)果Fig.3The calculation model and calculationresults of the rear leg

2 造橋機(jī)預(yù)壓載試驗(yàn)

2.1預(yù)壓載試驗(yàn)方案

以因地制宜為原則,采用沙袋和水作為預(yù)壓載荷材料.翼緣板、腹板和前后擋墻均堆沙袋,剩余加載載荷采用抽水替代,預(yù)壓載試驗(yàn)如圖所示.加載分3級(jí):0→60%→100%→104%,分別測(cè)試造橋機(jī)各測(cè)點(diǎn)的應(yīng)力值和主梁變形值.卸載也分3級(jí)進(jìn)行:104%→100%→60%→0,卸載后,觀察各測(cè)點(diǎn)變形值以及殘余應(yīng)力.

2.2結(jié)構(gòu)強(qiáng)度檢測(cè)方案

根據(jù)結(jié)構(gòu)有限元計(jì)算結(jié)果,在主梁、上橫梁、下掛梁、中支腿和后支腿等部位共選測(cè)點(diǎn)22個(gè),其中應(yīng)變片16個(gè),應(yīng)變花6個(gè).共需34個(gè)測(cè)量通道.

圖4 橫梁計(jì)算模型與計(jì)算結(jié)果Fig.4The calculation model and calculationresults of the beam

3 實(shí)驗(yàn)結(jié)果分析

3.1應(yīng)力值統(tǒng)計(jì)分析

3.1.1試驗(yàn)載荷下各測(cè)點(diǎn)應(yīng)力分布

加載到104%工況下,各測(cè)點(diǎn)應(yīng)力計(jì)算值與實(shí)測(cè)值對(duì)比分析如表1所示.由表1可知:① 各測(cè)點(diǎn)計(jì)算應(yīng)力與試驗(yàn)應(yīng)力基本吻合,均滿足強(qiáng)度要求;② 由左右側(cè)對(duì)稱位置實(shí)測(cè)值對(duì)比可以看出,右側(cè)應(yīng)力普遍大于左側(cè)應(yīng)力,左右中支腿處相差23 MPa,這可能由于制造誤差、安裝誤差等造成,在后續(xù)施工過(guò)程中應(yīng)加強(qiáng)觀察和檢查,尤其是在有風(fēng)載施工過(guò)程中.

表1 移動(dòng)模架預(yù)壓試驗(yàn)(加載104%工況)主要關(guān)鍵點(diǎn)結(jié)構(gòu)應(yīng)力值Tab.1Each measuring point structure stress value(104% load conditionof the overhead launching gantry of the preloading test

注:表格中,左右側(cè)是相對(duì)于移動(dòng)模架前進(jìn)方向而言;“-”為壓應(yīng)力;表中應(yīng)變花的應(yīng)力值為最大主應(yīng)力或最小主應(yīng)力中的絕對(duì)值較大者.

3.1.2加載過(guò)程中的應(yīng)力統(tǒng)計(jì)

由各測(cè)點(diǎn)在整個(gè)加載過(guò)程中的應(yīng)力變化曲線可知,各測(cè)點(diǎn)應(yīng)力值并非按線性規(guī)律增加,甚至出現(xiàn)加載過(guò)程中某時(shí)刻的應(yīng)力會(huì)超過(guò)最大載荷工況下的應(yīng)力(見圖5),這說(shuō)明由于加載過(guò)程中主梁載荷分布的不均勻性,會(huì)導(dǎo)致各測(cè)點(diǎn)并非一定在最大載荷下出現(xiàn)最大應(yīng)力.因此,對(duì)整個(gè)加載過(guò)程進(jìn)行檢測(cè)是非常必要的.

圖5 部分實(shí)驗(yàn)曲線圖(不考慮結(jié)構(gòu)自重影響) Fig.5 Part experimental value curves(ignoring the weight of the construction)

3.2撓度值統(tǒng)計(jì)分析

為了測(cè)得加載工況下的撓度曲線,參考主梁凈變形云圖,在兩側(cè)主梁沿縱向方向均布5個(gè)撓度測(cè)點(diǎn),位置分別為:0L,L/4,L/2,3L/4,L,其中L為主梁長(zhǎng)度.

100%加載工況下實(shí)測(cè)撓度曲線方程如圖6所示,該撓曲線方程可為預(yù)拱度調(diào)整提供依據(jù).由圖可知,主梁最大撓度發(fā)生在跨中位置,由于

故主梁滿足結(jié)構(gòu)剛度要求.

圖6 主梁撓曲線方程圖Fig.6 The deflection curve equation of main girder

4 結(jié)論

(1) 理論計(jì)算與現(xiàn)場(chǎng)加載試驗(yàn)表明,該MSS50雙幅整體澆筑式移動(dòng)模架造橋機(jī)滿足結(jié)構(gòu)的強(qiáng)度和剛度要求.

(2) 實(shí)測(cè)撓度曲線方程為施工中調(diào)整預(yù)拱度提供了依據(jù).

(3) 造橋機(jī)在加載過(guò)程中,由于載荷分布不均勻,各測(cè)點(diǎn)應(yīng)力和撓度并非按線性規(guī)律變化,有些測(cè)點(diǎn)甚至?xí)霈F(xiàn)瞬時(shí)應(yīng)力超過(guò)最大載荷時(shí)的應(yīng)力,所以對(duì)整個(gè)加載過(guò)程進(jìn)行全程監(jiān)控和檢測(cè)是必要的.

(4) 該MSS50雙幅整體澆筑時(shí)造橋機(jī)結(jié)構(gòu)龐大,承載量也很大,由于加工制造誤差和安裝誤差等原因,會(huì)造成結(jié)構(gòu)左右側(cè)對(duì)稱位置產(chǎn)生一定應(yīng)力偏差,在施工過(guò)程中,尤其在有風(fēng)載工況下施工時(shí),應(yīng)加強(qiáng)對(duì)偏差較大位置進(jìn)行觀察和檢查.

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CalculationanalysisandexperimentofstructuresecurityforthedoubleamplitudeintegrallyoverheadlaunchinggantryMIJiachuan

1,LüPengmin2,GUANZeqiang2,GUIFajun2,SHIYanni2

(1.Shandong Heng Kun Machinery Co.,Ltd.,Jinan 250014,China; 2.Key Laboratory for Highway Construction Technology and Equipment of Ministry of Education,Chang’an University,Xi’an 710064,China)

MSS50 double amplitude integrally overhead launching gantry was taken as study object in this paper.Using finite element analysis software,the strength and rigidity of it was checked.According to the results of the calculation,the stress and deformation test points were determined.Before the overhead launching gantry used,the pre-loading test was done.The tes tresults shown that:the analysis and experimental results were basically coincide,and the overhead launching gantry satisfied the intensity and the rigidity requirement.The measured deflection curve could provide reference for adjusting the pre-camber.As the non-uniformity of the actual load in the loading process,the stress of each measuring point did not change in the linear,even appearing the stress exceed the stress of the maximum loading case.Therefore,to monitor the loading process was necessary.Owing to the structure of the double amplitude overhead launching gantry very large,affected by the processing and installation error,the stress on the left-right legs appeared deviation and non-uniformity in loading processing,which should be strengthened the observation and detection in the construction processing,especially in the processing of wind load.The results in the paper can also provide reference for the design and construction of the overhead launching gantry.

double amplitude pouring; overhead launching gantry; finite element analysis; preloading test; pre-camber

U 445.36

A

1672-5581(2017)04-0365-05