【摘要】：我國(guó)大部分雙曲拱橋建于上世紀(jì)六、七十年代，由于設(shè)計(jì)荷載標(biāo)準(zhǔn)低、施工水平低，在長(zhǎng)期超負(fù)荷運(yùn)營(yíng)下?lián)p傷病害日益加劇；雙曲拱橋?qū)τ诓涣嫉刭|(zhì)條件的適應(yīng)性較差，地基沉降及基礎(chǔ)滑移等病害對(duì)雙曲拱橋的拱腳截面造成嚴(yán)重?fù)p害；同時(shí)，在我國(guó)溫差較大的東北地區(qū)，溫度應(yīng)力更加劇了這一病害狀況，導(dǎo)致雙曲拱橋?qū)嶋H工作狀態(tài)發(fā)生改變。隨著雙曲拱橋服役年限增長(zhǎng)，且面臨交通流量和車載逐步加大的風(fēng)險(xiǎn)，對(duì)雙曲拱橋進(jìn)行維修、加固，使其滿足現(xiàn)有交通正常運(yùn)營(yíng)要求，成為亟待解決的問題。本文從不良地質(zhì)條件下雙曲拱橋損傷后拱肋的實(shí)際受力狀況出發(fā)，針對(duì)拱腳已發(fā)生微小轉(zhuǎn)動(dòng)，形成半固結(jié)連接的真實(shí)情況，提出在既有的拱肋底部采取鋼桁架進(jìn)行加固的方法，并通過加固原理和計(jì)算理論分析、拱肋模型試驗(yàn)、數(shù)值模擬分析和實(shí)際工程現(xiàn)場(chǎng)試驗(yàn)，對(duì)該加固方法開展了相關(guān)的研究工作，并取得了一定的成果，主要有： （1）查閱了大量的相關(guān)資料文獻(xiàn)，回顧雙曲拱橋在特定歷史時(shí)期的發(fā)展歷程，對(duì)雙曲拱橋的各構(gòu)件的構(gòu)造特點(diǎn)、施工技術(shù)手段及其加固方法進(jìn)行了總結(jié)，剖析不良地質(zhì)條件對(duì)雙曲拱橋的損害機(jī)理及病害特點(diǎn)，分析了鋼桁架加固雙曲拱橋方法的可行性。 （2）對(duì)兩鉸拱的力學(xué)性能進(jìn)行研究，分析指出活荷載彎矩的抵抗能力不足是導(dǎo)致雙曲拱拱橋承載能力降低的主要因素；并在此基礎(chǔ)上研究分析鋼桁架加固兩鉸雙曲拱橋方法的力學(xué)原理。 （3）在分析鋼桁架加固雙曲拱橋結(jié)構(gòu)構(gòu)件實(shí)際受力狀況的基礎(chǔ)上，提出將原拱肋視作能夠承受彎矩的剛性構(gòu)件，鋼桁架的腹桿和下弦桿視為承受軸向力的構(gòu)件，建立了鋼桁架加固雙曲拱橋的力學(xué)簡(jiǎn)化模型。通過對(duì)鋼桁架的幾何形狀參數(shù)的影響因素的分析，提出了鋼桁架幾何形狀設(shè)計(jì)的合理建議。在力學(xué)簡(jiǎn)化模型的基礎(chǔ)上，按照桁梁混合結(jié)構(gòu)的研究思路，提出了鋼桁架加固雙曲拱橋拱肋的力法計(jì)算方法。 （4）運(yùn)用通用有限元程序ABAQUS對(duì)加固前后模型進(jìn)行非線性分析，結(jié)果表明加固后拱肋彎矩降低，拱肋的受力狀態(tài)更加合理，承載能力提高了2.4倍。 （5）制作了2個(gè)拱肋試驗(yàn)?zāi)Ｐ停謩e為未加固拱肋模型和采用鋼桁架加固的拱肋模型；并進(jìn)行跨中集中力加載。從試驗(yàn)現(xiàn)象來看，未加固拱肋模型在跨中出現(xiàn)豎直向上發(fā)展的裂縫，接近破壞階段時(shí)，在1/8跨附近出現(xiàn)上部裂縫。采用鋼桁架加固后試件跨中裂縫開展明顯減小，在混凝土拱肋上部未出現(xiàn)裂縫。 （6）在試驗(yàn)過程中，未加固拱肋在1/8跨處撓度出現(xiàn)先向下發(fā)展后向上發(fā)展的現(xiàn)象，在1/4跨、3/8跨和跨中處撓度隨荷載增加均保持向下發(fā)展；鋼桁架加固拱肋所有測(cè)點(diǎn)位置處撓度均向下發(fā)展，兩拱肋撓度增長(zhǎng)分布情況相同，，跨中撓度增長(zhǎng)速度最大，依次向支座方向遞減。由數(shù)據(jù)分析可知，加固后撓度隨荷載線性增長(zhǎng)狀態(tài)程度優(yōu)于未加固拱肋，除1/8跨位置外，其余測(cè)點(diǎn)位置處撓度增速均小于未加固拱肋，表明采用鋼桁架進(jìn)行加固后，試件的整體剛度更加勻稱，構(gòu)件整體化程度顯著提高。 （7）通過對(duì)試驗(yàn)應(yīng)變數(shù)據(jù)整理分析可知，采用鋼桁架加固后，混凝土拱肋在1/8跨、1/4跨處彎矩大幅降低，截面始終保持受壓狀態(tài)；3/8跨位置處和跨中處下部縱向鋼筋拉應(yīng)變值大幅降低，截面主要承受壓力；表明加固后拱肋截面的彎矩減小，受力狀態(tài)更加合理，采用鋼桁架加固后，拱肋的開裂荷載、屈服荷載、極限荷載分別提高2.94倍、2.28倍、2.21倍，試件的承載能力大幅度提高。 （8）對(duì)長(zhǎng)安大橋采用鋼桁架進(jìn)行加固，并進(jìn)行了橋梁荷載試驗(yàn)，試驗(yàn)數(shù)據(jù)表明加固后結(jié)構(gòu)整體受力性能得到顯著改善，橋梁結(jié)構(gòu)的承載能力和整體剛度明顯提升，達(dá)到預(yù)期的加固效果；證明鋼桁架加固雙曲拱橋方法是可行的。
[Abstract]:Most of the double-curved arch bridges in China were built in the 1960s and 1970s. Due to the low design load standard and construction level, the damage of the double-curved arch bridges under long-term overload operation is becoming more and more serious. At the same time, in Northeast China where the temperature difference is large, the temperature stress aggravates the disease, which leads to the change of the actual working state of the double-curved arch bridge. Based on the actual stress condition of damaged arch ribs of double-curved arch bridges under bad geological conditions and the fact that the arch foot has turned slightly to form a semi-consolidated connection, a method of strengthening the existing arch rib bottom with steel truss is proposed in this paper. The arch rib model test, numerical simulation analysis and actual engineering field test have carried out relevant research work on the reinforcement method, and achieved some results, mainly as follows:
(1) Reviewing the development course of the double-curved arch bridge in a specific historical period by consulting a large number of relevant documents, summing up the structural characteristics, construction techniques and reinforcement methods of the components of the double-curved arch bridge, analyzing the damage mechanism and disease characteristics of the double-curved arch bridge caused by bad geological conditions, and analyzing the square of the double-curved arch bridge strengthened by steel truss. The feasibility of the law.
(2) The mechanical properties of two-hinged arch are studied, and it is pointed out that the insufficient resistance to live load moment is the main factor leading to the reduction of the bearing capacity of double-curved arch bridge.
(3) On the basis of analyzing the actual stress state of the structural members of the double-curved arch bridge strengthened with steel truss, the paper puts forward that the original arch rib is regarded as a rigid member which can bear bending moment, and the web bar and the lower chord bar of the steel truss are regarded as members which bear axial force. The simplified mechanical model of the double-curved arch bridge strengthened with steel truss is established. Based on the simplified mechanical model and the research idea of the truss-beam hybrid structure, a force method for calculating the arch ribs of the double-curved arch bridge strengthened by the steel truss is proposed.
(4) The finite element program ABAQUS is used to analyze the non-linear model before and after reinforcement. The results show that the bending moment of the arch rib is reduced, the stress state of the arch rib is more reasonable, and the bearing capacity is increased by 2.4 times.
(5) Two test models of arch ribs were made, which were the unreinforced arch rib model and the steel truss reinforced arch rib model, and were loaded with concentrated force in the middle of the span. The cracks in the mid span of the concrete specimens were significantly reduced, and no cracks appeared on the upper part of the concrete arch ribs.
(6) During the test, the deflection of the unreinforced arch rib develops downward first and then upwards at the 1/8 span, and keeps downward with the increase of load at the 1/4 span, 3/8 span and the middle of the span; the deflection at all measuring points of the arch rib strengthened by steel truss develops downward, and the deflection distribution of the two arch ribs is the same, and the deflection growth rate at the middle of the span is the same. According to the data analysis, the deflection of the strengthened arch rib is better than that of the unreinforced arch rib, except for the 1/8 span position, the deflection of the other measuring points is less than that of the unreinforced arch rib, which indicates that the overall stiffness of the specimens is more symmetrical and the integral degree of the members is more than that of the unreinforced arch rib. Marked improvement.
(7) According to the analysis of the test strain data, the bending moment of concrete arch rib decreases greatly at 1/8 span and 1/4 span, and the section keeps compression state after strengthening with steel truss; the tensile strain value of longitudinal reinforcement decreases greatly at 3/8 span and lower part of midspan, and the section bears pressure mainly; it shows that the bending moment of arch rib section decreases after strengthening. The cracking load, yield load and ultimate load of the arch rib are increased by 2.94 times, 2.28 times and 2.21 times respectively after strengthening with steel truss.
(8) The steel truss is used to reinforce Chang'an Bridge, and the load test of the bridge is carried out. The test data show that the overall mechanical performance of the structure has been significantly improved, the bearing capacity and overall stiffness of the bridge structure have been significantly improved, and the expected reinforcement effect has been achieved.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：U445.72

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