【摘要】：混凝土開(kāi)裂嚴(yán)重影響橋梁結(jié)構(gòu)耐久性的和安全性,溫差拉應(yīng)力是造成混凝土箱形結(jié)構(gòu)開(kāi)裂的主要因素之一,而合理的溫差分布模式是準(zhǔn)確計(jì)算溫差應(yīng)力的基礎(chǔ),但目前有關(guān)箱形墩及魚(yú)腹形箱梁溫度作用的研究較少,因此對(duì)混凝土橋梁結(jié)構(gòu)溫差效應(yīng)進(jìn)行深入的探討和研究是必要的。本文依托實(shí)際工程項(xiàng)目,基于現(xiàn)場(chǎng)溫度作用實(shí)測(cè)結(jié)果及參數(shù)分析,對(duì)混凝土箱形結(jié)構(gòu)溫度作用進(jìn)行了研究,主要內(nèi)容如下:(1)根據(jù)混凝土箱形墩日照作用連續(xù)觀測(cè)結(jié)果,總結(jié)了其日照溫度場(chǎng)及溫度效應(yīng)的變化規(guī)律;基于參數(shù)分析結(jié)果,討論了壁面方位角對(duì)日照正溫差分布的影響,并計(jì)算了不同溫差分布模式下的溫差效應(yīng),據(jù)此確定了不同朝向箱形墩日照正溫差分布模式。分析結(jié)果表明:墩壁朝向不同,最大溫差出現(xiàn)時(shí)刻有差別,墩壁達(dá)到的最大溫差值也不同,壁面方位角與溫差最大值的關(guān)系近似為正弦函數(shù)分布。(2)基于混凝土箱形墩寒流降溫作用下的連續(xù)觀測(cè)結(jié)果及溫度場(chǎng)和溫致效應(yīng)的參數(shù)分析,研究了降溫速率、降溫幅度和壁厚變化對(duì)溫差分布的影響,確定了不同壁厚箱形墩負(fù)溫差分布模式。結(jié)果表明:寒流降溫作用下,混凝土箱形墩各側(cè)溫差分布基本一致;壁厚不同的箱形墩,其溫差分布模式不同;在相同降溫幅度下,降溫時(shí)刻的初始溫度分布對(duì)箱形墩降溫過(guò)程中的結(jié)構(gòu)反應(yīng)增量影響較小;對(duì)壁厚0.6m的箱形墩,大氣降溫20℃所導(dǎo)致負(fù)溫差產(chǎn)生的橫向拉應(yīng)力可達(dá)3.6MPa,應(yīng)引起足夠的重視。(3)基于魚(yú)腹形箱梁瞬態(tài)溫度場(chǎng)的分析結(jié)果提出了其日照溫差計(jì)算模式,并對(duì)三跨連續(xù)箱梁橋的空間溫度效應(yīng)進(jìn)行了分析,與采用現(xiàn)行公路橋規(guī)溫差模式的計(jì)算結(jié)果進(jìn)行了對(duì)比。結(jié)果表明:橫向溫差對(duì)魚(yú)腹形箱梁最大橫向拉應(yīng)力的影響很小,可忽略橫向溫差的影響;現(xiàn)行公路橋規(guī)采用的折線形豎向溫差梯度模式與實(shí)際箱梁溫度分布有較大差別,導(dǎo)致對(duì)溫度效應(yīng)的考慮不足,建議在設(shè)計(jì)中采用指數(shù)函數(shù)形式的豎向溫差梯度模式。
[Abstract]:Concrete cracking seriously affects the durability and safety of bridge structure. Temperature differential tensile stress is one of the main factors that cause concrete box structure cracking, and reasonable temperature difference distribution model is the basis of accurate calculation of temperature differential stress. However, there are few researches on the temperature effects of box piers and fish-bellied box girders, so it is necessary to study the effect of temperature difference of concrete bridges. Based on the actual project, the temperature effect of concrete box structure is studied based on the measured results of field temperature and parameter analysis. The main contents are as follows: (1) according to the continuous observation results of sunshine action of concrete box pier, Based on the results of parameter analysis, the effect of wall azimuth on the distribution of positive temperature difference of sunlight is discussed, and the effect of temperature difference under different temperature distribution modes is calculated. According to this, the distribution model of normal temperature difference of sunshine in different directions of box pier is determined. The results show that the maximum temperature difference is different with the direction of the pier wall, and the maximum temperature difference value of the pier wall is also different. The relationship between the wall azimuth and the maximum temperature difference is approximately a sinusoidal function distribution. (2) based on the continuous observation results of the cold current of concrete box pier and the parameter analysis of temperature field and temperature effect, the cooling rate is studied. The negative temperature difference distribution mode of box pier with different wall thickness is determined by the influence of temperature drop range and wall thickness on the temperature difference distribution. The results show that the temperature difference distribution of concrete box pier is basically the same, the temperature difference distribution mode of box pier with different wall thickness is different, and under the same cooling range, the temperature difference distribution of concrete box pier is basically the same. The initial temperature distribution at the cooling time has little effect on the increment of structural response in the cooling process of the box pier, and on the box pier with a wall thickness of 0.6 m. The transverse tensile stress caused by negative temperature difference due to 20 鈩，

本文編號(hào)：2260410