發(fā)布時(shí)間：2018-06-17 12:18

  本文選題：PC箱梁橋 + 反向裂縫�。� 參考：《長(zhǎng)安大學(xué)》2014年碩士論文

【摘要】：箱形梁由于其良好的結(jié)構(gòu)性能，在PC梁橋中應(yīng)用廣泛。但是該類(lèi)橋梁在懸臂施工中箱梁腹板經(jīng)常會(huì)出現(xiàn)與常規(guī)受剪裂縫走向垂直的斜裂縫——反向斜裂縫。目前工程界已公認(rèn)此裂縫會(huì)影響橋梁整體安全性、實(shí)用性及耐久性，但是截至目前，技術(shù)人員對(duì)該類(lèi)裂縫的形成機(jī)理，以及如何防范還沒(méi)有給出一個(gè)明確的答案。因此本文旨在開(kāi)展腹板反向斜裂縫的研究，尋找其形成原因，同時(shí)為新建橋梁防止該類(lèi)病害的發(fā)生提供改進(jìn)建議。 本文以某連續(xù)剛構(gòu)橋?yàn)楣こ瘫尘埃\(yùn)用大型有限元計(jì)算軟件ABAQUS分析了懸臂施工連續(xù)剛構(gòu)箱梁橋腹板反向斜裂縫產(chǎn)生的原因，主要內(nèi)容和結(jié)論結(jié)論如下： （1）分析給出了考慮豎向預(yù)應(yīng)力、縱向預(yù)應(yīng)力、剪力滯效應(yīng)等因素下的施工階段箱梁的應(yīng)力的計(jì)算公式。 （2）借助ABAQUS軟件計(jì)算各種工況下腹板沿預(yù)應(yīng)力方向預(yù)應(yīng)力筋附近混凝土的主拉應(yīng)力，并分析了造成腹板方向開(kāi)裂的原因，對(duì)比分析了考慮預(yù)應(yīng)力管道和不考慮預(yù)應(yīng)力管道應(yīng)力分布的差異。 （3）在對(duì)預(yù)應(yīng)力混凝土箱梁橋腹板反向斜裂縫影響因素研究的基礎(chǔ)上，分別從箱梁橋的設(shè)計(jì)、施工、維修等層面提出了應(yīng)對(duì)措施和建議。 （4）張拉豎向預(yù)應(yīng)力筋對(duì)腹板受力有利，因此張拉完縱向預(yù)應(yīng)力筋后應(yīng)及時(shí)張拉豎向預(yù)應(yīng)力。 （5）考慮預(yù)應(yīng)力管道后腹板主拉應(yīng)力明顯大于不考慮管道的情況，因此在計(jì)算中應(yīng)該考慮預(yù)應(yīng)力孔道的影響。 （6）造成腹板反向斜裂縫的主要原因是張拉腹板縱向預(yù)應(yīng)力時(shí)錨固端應(yīng)力集中和豎彎處徑向力過(guò)大導(dǎo)致主拉應(yīng)力超限。此外，張拉時(shí)機(jī)提前，，混凝土早期齡期未達(dá)到設(shè)計(jì)值也是一個(gè)不容忽視的原因。
[Abstract]:Box beam is widely used in PC beam bridge because of its good structure performance. However, in the cantilever construction of this kind of bridge, the box girder web plate often appears the oblique crack-reverse oblique crack which is perpendicular to the conventional shear crack. At present, it has been recognized that the crack will affect the overall safety, practicability and durability of the bridge. However, up to now, the technicians have not given a clear answer to the formation mechanism of this kind of crack and how to prevent it. Therefore, the purpose of this paper is to study the reverse oblique cracks of web plates, to find out the causes of the cracks, and to provide suggestions for the new bridges to prevent the occurrence of this kind of diseases. Taking a continuous rigid frame bridge as the engineering background, this paper analyzes the causes of the reverse oblique cracks in the web of the cantilever construction continuous rigid frame box girder bridge by using the large scale finite element calculation software Abaqus. The main contents and conclusions are as follows: (1) the vertical prestress and longitudinal prestress are considered. Calculation formula of box girder stress in construction stage under shear lag effect and other factors. (2) the main tensile stress of concrete near prestressed tendons in different working conditions is calculated by Abaqus software. The causes of the cracking in the web direction are also analyzed. This paper compares and analyzes the difference of stress distribution between prestressed pipe and non-prestressed pipe. On the basis of the research on the factors affecting the reverse oblique crack of web of prestressed concrete box girder bridge, the design and construction of box girder bridge are carried out respectively. At the maintenance and other levels, the countermeasures and suggestions are put forward. (4) the tension of vertical prestressed tendons is favorable to the web. Therefore, when the longitudinal prestressed tendons are finished, the vertical prestress should be tensioned in time. (5) the main tensile stress of the web plate after the consideration of the prestressed pipe is obviously greater than that without considering the pipeline. Therefore, the influence of prestress channels should be taken into account in the calculation. The main reason for the reverse oblique cracks of web plate is the stress concentration at the anchoring end and the excessive radial force at the vertical bend, which leads to the over-limit of the main tensile stress during the longitudinal prestressing of the web tensioning plate. In addition, the early tensioning time and the early age of concrete not reaching the design value are also a reason that can not be ignored.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：U448.213;U441.6

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