本文選題：預(yù)應(yīng)力混凝土箱梁 + 裂縫�。� 參考：《重慶交通大學(xué)》2015年碩士論文

【摘要】：近年來,隨著交通事業(yè)的迅猛發(fā)展,我國橋梁建設(shè)水平已邁上新臺階。預(yù)應(yīng)力混凝土箱梁橋因截面抗彎、抗扭剛度大,施工方便,造價低廉等優(yōu)勢而頗具競爭力,該橋型近些年無論在規(guī)模還是跨徑方面都取得了較大突破,但隨之而產(chǎn)生的問題也越來越多,其中開裂問題在已建或在建工程中均較為普遍。在建工程中出現(xiàn)開裂問題會影響后續(xù)施工的質(zhì)量與安全,使結(jié)構(gòu)存在缺陷并埋下隱患,而已建成橋梁出現(xiàn)裂縫不僅影響結(jié)構(gòu)美觀,同時對結(jié)構(gòu)的安全性及耐久性均構(gòu)成較大的威脅,因此有必要對混凝土箱梁開裂問題進(jìn)行系統(tǒng)深入的研究,探索產(chǎn)生這一病害的根本緣由。本文以廣元市江口嘉陵江大橋為研究背景并結(jié)合現(xiàn)場實際情況,對預(yù)應(yīng)力混凝土箱梁橋裂縫的影響因素展開研究,具體工作內(nèi)容歸納如下:①通過查閱大量關(guān)于預(yù)應(yīng)力混凝土箱梁橋開裂的書籍和相關(guān)文獻(xiàn),對此類問題有了一定的認(rèn)知,并通過總結(jié)分析,得到了裂縫的成因、分布特點及力學(xué)特征,以指導(dǎo)后續(xù)工作更好地開展。②通過有限元分析,結(jié)合我國現(xiàn)行規(guī)范得到了豎向溫度梯度對橋梁受力的影響規(guī)律,并對比分析了最不利溫度梯度效應(yīng)與活載效應(yīng)關(guān)系,說明了溫度梯度對橋梁受力影響很大;同時選取另外兩種外國規(guī)范,計算分析后發(fā)現(xiàn):三種規(guī)范下的溫度梯度效應(yīng)相差較大,因此在氣候環(huán)境或工程背景特殊的情況下,應(yīng)對現(xiàn)場溫度觀測,得到更為準(zhǔn)確的溫度效應(yīng)。③通過計算分析頂、底板縱向預(yù)應(yīng)力損失對全橋縱向應(yīng)力的影響規(guī)律,得出其最不利影響區(qū)間,為以后工程設(shè)計提供有益參考。④運用ANSYS大型通用有限元分析模擬箱梁裂縫實際分布位置,并通過計算分析發(fā)現(xiàn):在縱向預(yù)應(yīng)力筋正常工作的情況下,豎向預(yù)應(yīng)力損失過大和腹板尺寸設(shè)計不合理是引起箱梁腹板產(chǎn)生裂縫的主要原因。⑤通過對裂縫的成因、分布位置、影響因素等方面分析研究,從縱、豎向預(yù)應(yīng)力的改進(jìn)、合理配筋、箱梁尺寸、溫度效應(yīng)、施工工藝等方面提出了箱梁裂縫控制措施,并針對不同裂縫提出了對應(yīng)的修補措施。
[Abstract]:In recent years, with the rapid development of transportation, the level of bridge construction in China has reached a new level. The prestressed concrete box girder bridge is competitive because of the advantages of flexural section, large torsional stiffness, convenient construction and low cost. In recent years, the bridge type has made a great breakthrough in both scale and span. However, there are more and more problems, of which cracking is common in both existing and ongoing construction projects. The cracking problem in construction will affect the quality and safety of the subsequent construction, make the structure have defects and bury hidden dangers, but the cracks in the completed bridge will not only affect the beauty of the structure. At the same time, the safety and durability of the structure pose a great threat, so it is necessary to study the cracking of concrete box girder systematically and deeply, to explore the root cause of the disease. In this paper, based on the background of Jiangkou Jialing River Bridge in Guangyuan City and the actual situation on the spot, the factors affecting the cracks of prestressed concrete box girder bridge are studied. The specific work contents are summarized as follows: 1. Through consulting a large number of books and related documents on cracking of prestressed concrete box girder bridges, we have a certain understanding of this kind of problems, and through summing up and analyzing, we get the causes of the cracks. Distribution characteristics and Mechanical characteristics, in order to guide the follow-up work, the influence of vertical temperature gradient on the stress of bridges is obtained through finite element analysis and combining with the current code of our country. The relationship between the most unfavorable temperature gradient effect and the live load effect is compared and analyzed, which shows that the temperature gradient has a great influence on the bridge force, and two other foreign codes are selected at the same time. After calculation and analysis, it is found that the temperature gradient effect under the three specifications is quite different. Therefore, in the case of special climatic environment or engineering background, a more accurate temperature effect of .3 can be obtained by calculating and analyzing the temperature observation in the field. The influence law of the longitudinal prestressing loss on the longitudinal stress of the whole bridge is obtained, and the most unfavorable section is obtained, which provides a useful reference for the future engineering design. 4. The actual distribution of box girder cracks is simulated by using ANSYS large and universal finite element analysis. Through calculation and analysis, it is found that under the condition of normal working of longitudinal prestressed tendons, excessive loss of vertical prestress and unreasonable design of web size are the main causes of cracks in box girder webs. Based on the analysis of the influencing factors, the paper puts forward the crack control measures of box girder from the aspects of the improvement of longitudinal and vertical prestress, reasonable reinforcement, box girder size, temperature effect and construction technology, and puts forward corresponding repair measures for different cracks.
【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】：U445.57

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本文編號：1829440