發(fā)布時間：2018-10-08 16:26

【摘要】：連續(xù)剛構(gòu)橋具有跨越能力大、施工簡便、造價經(jīng)濟、行車舒適等優(yōu)點,受到工程師所青睞。通過對大量連續(xù)剛構(gòu)橋的檢測發(fā)現(xiàn)這種橋型在施工和運營階段出現(xiàn)了相當(dāng)數(shù)量的裂縫,裂縫對于橋梁的安全性和耐久性都有不利的影響。連續(xù)剛構(gòu)橋具有廣闊的前景,連續(xù)剛構(gòu)橋的開裂研究對橋梁施工、設(shè)計和養(yǎng)護都有利。本文主要以趕水大橋為工程背景,計算大橋在施工階段和成橋階段箱梁應(yīng)力,分析寬箱梁結(jié)構(gòu)裂縫。用Midas civil分析了趕水大橋的施工過程,重點分析了橋梁體系轉(zhuǎn)換過程梁段內(nèi)力變化,比較了不同施工階段合攏段底板應(yīng)力變化。用ANSYS殼單元SHELL63建立全橋模型,分析寬箱梁的剪力滯和畸變,將殼單元計算結(jié)果與桿件單元計算結(jié)果進行比較,從而得到剪力滯系數(shù)。分析了三向預(yù)應(yīng)力對空間箱梁的力學(xué)行為。主要工作有:比較分析設(shè)置頂板橫向預(yù)應(yīng)力和沒有設(shè)置頂板橫向預(yù)應(yīng)力下寬箱梁頂板應(yīng)力橫向分布;分析豎向預(yù)應(yīng)力對腹板主應(yīng)力的控制效應(yīng),計算比較腹板在不同豎向預(yù)應(yīng)力損失情況下的主應(yīng)力,分析比較各個梁段腹板受拉區(qū)。對趕水大橋成橋狀態(tài)箱梁結(jié)構(gòu)進行分析。分析預(yù)應(yīng)力損失對跨中梁段撓度和底板應(yīng)力的影響。通過空間有限元模型分析局部梁段,提出一些預(yù)防開裂的措施。在趕水大橋的設(shè)計基礎(chǔ)上,分別作了以下工作:計算了不同底板線形箱梁底板的徑向力。計算了寬箱梁施加橫向肋和未加橫向肋箱梁的應(yīng)力。建立了不同腹板厚度的箱梁模型,比較了不同腹板厚度的腹板主應(yīng)力分布。以徑向力公式計算出合攏段底板徑向力,建立了合攏段底板有限元模型。計算了不同厚度保護層底板的應(yīng)力,比較孔道壁的應(yīng)力分布。通過對前面的計算分析,知道橋梁體系轉(zhuǎn)換過程中合攏段底板受到較大的徑向力。徑向力大的梁段底板由于箱梁變形和混凝土泊松效應(yīng)產(chǎn)生橫向彎矩,容易產(chǎn)生縱向裂縫。合攏段附近梁段采用高冪次底板線形,更不容易產(chǎn)生縱向裂縫。徑向力大的梁段增加橫向肋可以增加底板橫向剛度,減小橫向拉應(yīng)力,防止結(jié)構(gòu)裂縫。底板保護層厚度增加對孔道壁附近應(yīng)力影響不大,對改善底板下緣受拉作用有限。頂板橫向預(yù)應(yīng)力使得頂板具有一定的壓力儲備,但是產(chǎn)生的橫向彎矩使得翼緣板下緣受拉,特別是翼緣板下緣容易產(chǎn)生縱向裂縫。豎向預(yù)應(yīng)力和剪力控制腹板主應(yīng)力,當(dāng)豎向預(yù)應(yīng)力損失到一定值對控制腹板主應(yīng)力不起控制作用。
[Abstract]:Continuous rigid frame bridge is favored by engineers for its advantages of large span capacity, simple construction, economical cost and comfortable driving. Through the detection of a large number of continuous rigid frame bridges, it is found that there are quite a number of cracks in the construction and operation stages of the bridges, which have adverse effects on the safety and durability of the bridges. Continuous rigid frame bridge has a broad prospect. The research on crack of continuous rigid frame bridge is beneficial to bridge construction, design and maintenance. In this paper, the stress of box girder in the construction stage and the completion stage of the bridge is calculated, and the cracks of the wide box girder structure are analyzed. The construction process of Shuishui Bridge is analyzed by Midas civil. The variation of internal force of beam section during the transition of bridge system is emphatically analyzed and the stress changes of bottom slab of closed section in different construction stages are compared. The full bridge model is established by using ANSYS shell element SHELL63, and the shear lag and distortion of wide box girder are analyzed. The calculated results of shell element are compared with those of member element, and the shear lag coefficient is obtained. The mechanical behavior of three-dimensional prestressing on space box girder is analyzed. The main works are as follows: comparing and analyzing the transverse stress distribution of the wide box girder roof with and without the transverse prestress of the roof, analyzing the control effect of the vertical prestress on the principal stress of the web plate, and analyzing the control effect of the vertical prestress on the main stress of the web plate. The principal stresses of webs under different vertical prestress losses are calculated and compared. The box girder structure of Shuishui Bridge is analyzed. The effect of prestress loss on deflection and bottom stress of mid-span beam is analyzed. Based on the spatial finite element model, the local beam section is analyzed, and some measures to prevent the crack are put forward. Based on the design of Shuihui Bridge, the following works are done: the radial force of different bottom plate linear box girder is calculated. The stress of wide box girder with and without transverse rib is calculated. The box girder model with different web thickness is established and the principal stress distribution of web with different web thickness is compared. The radial force of the bottom plate of the closed section is calculated by the formula of radial force, and the finite element model of the bottom plate of the closure section is established. The stress distribution of the hole wall is compared by calculating the stress of the bottom plate with different thickness of the protective layer. Through the calculation and analysis of the front, it is known that the bottom plate of the closing section is subjected to a large radial force during the transition of the bridge system. Due to box girder deformation and concrete Poisson effect, transverse bending moment of beam bottom plate with large radial force is easy to produce longitudinal cracks. The beam section near the closure section adopts the linear form of high power bottom plate, which makes it less easy to produce longitudinal cracks. The transverse stiffness of the bottom plate can be increased and the transverse tensile stress can be reduced by increasing the transverse rib in the beam section with large radial force and preventing the structural cracks. The thickness of the protective layer of the bottom plate has little effect on the stress near the hole wall, but it has limited effect on the improvement of the lower edge of the bottom plate. The transverse prestressing makes the roof have a certain pressure reserve, but the transverse bending moment makes the flange plate lower edge tension, especially the flange plate lower edge easy to produce longitudinal cracks. The main stress of web plate is controlled by vertical prestress and shear force. When the loss of vertical prestress reaches a certain value, it can not control the principal stress of web plate.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U441;U445.4

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本文編號：2257449