本文選題：大跨度連續(xù)箱梁橋 + 溫度效應(yīng)��； 參考：《中南大學》2014年碩士論文

【摘要】：國內(nèi)外的調(diào)查資料表明,混凝土中的早期裂縫是大跨度連續(xù)箱梁橋施工實踐中出現(xiàn)的普遍問題。其中,溫度效應(yīng)是早期裂縫產(chǎn)生的重要影響因素。本文以一大跨徑連續(xù)剛構(gòu)箱梁橋為工程背景,對箱梁橋施工階段截面溫度梯度和水化熱效應(yīng)進行分析研究,提出相應(yīng)的溫度控制措施,為防治大跨度箱梁橋的早期裂縫問題提供理論分析依據(jù)。 文章利用ANSYS10.0的三維溫度實體單元,考慮太陽輻射、大氣溫度、混凝土表面吸收與發(fā)散熱輻射等參數(shù),計算施工過程中無橋面鋪裝狀況下的截面梯度溫度場與實測溫度進行對比分析,并根據(jù)溫度場計算結(jié)果擬合適合于無橋面鋪裝箱梁溫度梯度計算模式,進行施工及合龍后箱梁截面應(yīng)力分析。同時,采用Midas civil2012的水化熱計算模塊,根據(jù)實際工程參數(shù),計算箱梁懸澆過程中水化熱在結(jié)構(gòu)中的分布和時程變化規(guī)律,并將計算值與實測值對比,檢驗計算值的正確性。 溫度梯度及水化熱計算結(jié)果表明：大跨度連續(xù)箱梁橋施工階段的日照溫度場與公路橋規(guī)的計算模式存在一定的差異,豎向及橫向溫度梯度比較符合指數(shù)曲線分布。由于懸臂板遮陽的效果不同,中間支點處梁段與跨中梁段應(yīng)采用不同的溫度模式。日照溫度梯度作用下,箱梁在懸臂澆筑過程中產(chǎn)生了較大的縱橫向拉應(yīng)力,尤其是箱梁合龍后,由于溫度自應(yīng)力與次應(yīng)力的共同作用,跨中截面的縱向拉應(yīng)力尤為顯著。箱梁懸澆過程中,水化熱效應(yīng)使得箱梁在節(jié)段交接位置及頂?shù)装迮c腹板倒角處出現(xiàn)較大的拉應(yīng)力,極易在施工過程中出現(xiàn)開裂現(xiàn)象。為了盡量降低施工過程中溫度效應(yīng)對箱梁的影響,可以采用選擇澆筑時間,低水化熱水泥,添加適量的緩凝劑,合理的養(yǎng)護及澆筑方案等溫度控制措施。 本文對大跨徑預(yù)應(yīng)力混凝土箱梁橋早期溫度裂縫的防治進行了有益地探索,可為橋梁設(shè)計及施工提供參考。
[Abstract]:The investigation data at home and abroad show that the early crack in concrete is a common problem in the construction practice of long-span continuous box girder bridge. Among them, temperature effect is an important influence factor of early cracks. Taking a long-span continuous rigid frame box girder bridge as the engineering background, this paper analyzes and studies the temperature gradient and hydration heat effect of the section in the construction stage of the box girder bridge, and puts forward the corresponding temperature control measures. It provides theoretical basis for preventing and curing early crack of long span box girder bridge. In this paper, the three-dimensional temperature solid element of ANSYS10.0 is used to consider the parameters of solar radiation, atmospheric temperature, absorption and heat radiation of concrete surface, etc. The cross-section gradient temperature field under the condition of no bridge deck paving is compared with the measured temperature during the construction process, and the temperature gradient calculation model of box girder without bridge deck pavement is fitted according to the temperature field calculation results. The section stress analysis of box girder after construction and closure is carried out. At the same time, using the hydration heat calculation module of Midas civil2012, according to the actual engineering parameters, the distribution of hydration heat in the structure and the time history change law of the box girder are calculated, and the calculated values are compared with the measured values to verify the correctness of the calculated values. The results of temperature gradient and hydration heat calculation show that there are some differences between the temperature field of sunshine and the calculation model of highway bridge gauge in the construction stage of long-span continuous box girder bridge. The vertical and lateral temperature gradient are in accordance with the exponential curve distribution. Because of the different sunshade effect of the cantilever plate, different temperature modes should be adopted between the middle fulcrum and the middle span beam. Under the action of sunshine temperature gradient, the longitudinal and transverse tensile stress of box girder is produced in the process of cantilever pouring, especially after the closure of box girder, the longitudinal tensile stress of the mid-span section is especially obvious due to the interaction of temperature self-stress and secondary stress. During the casting process of box girder, the heat effect of hydration causes the large tensile stress at the joint position of the section and the chamfer between the top and bottom plate and the web, so it is easy to crack in the construction process. In order to reduce the influence of temperature effect on box girder during construction, temperature control measures such as selecting pouring time, low hydration heat cement, adding appropriate amount of retarder, reasonable maintenance and pouring scheme can be adopted. In this paper, the prevention and control of the early temperature cracks in the long span prestressed concrete box girder bridge are discussed, which can be used as a reference for the design and construction of the bridge.
【學位授予單位】：中南大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U445.4;U441.5

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本文編號：1869801