發(fā)布時(shí)間：2018-04-11 08:23

  本文選題：混凝土 + 收縮徐變��； 參考：《湖南科技大學(xué)》2014年碩士論文

【摘要】：混凝土的收縮徐變機(jī)理比較復(fù)雜，不確定影響因素較多，是引起預(yù)應(yīng)力混凝土梁橋跨中下?lián)线^大主要原因之一。為了提高收縮徐變對(duì)混凝土梁橋結(jié)構(gòu)行為影響的認(rèn)識(shí)，本文通過大量混凝土圓柱體和鋼筋混凝土圓柱體的長期試驗(yàn)研究，總結(jié)出混凝土和鋼筋混凝土長期收縮徐變規(guī)律，并提出混凝土和鋼筋混凝土構(gòu)件收縮徐變計(jì)算模型，提高了對(duì)混凝土和鋼筋混凝土構(gòu)件收縮徐變預(yù)測(cè)精度。主要內(nèi)容如下： （1）通過對(duì)混凝土圓柱試件收縮應(yīng)變的長期測(cè)試和不同加載齡期的混凝土圓柱體進(jìn)行長期徐變?cè)囼?yàn)，得到混凝土收縮徐變長期變化規(guī)律，，在用B3變異系數(shù)和B3方差對(duì)國內(nèi)外的收縮徐變預(yù)測(cè)模型進(jìn)行對(duì)比研究的基礎(chǔ)上，提出新的混凝土收縮應(yīng)變預(yù)測(cè)模型，同時(shí)對(duì)CEB-FIP（1990）徐變模型進(jìn)行了修正。 （2）通過6根素混凝土（鋼筋混凝土）柱徐變對(duì)比試驗(yàn)，研究了鋼筋混凝土圓柱徐變特性，結(jié)合CEB-FIP（1990）和中國建科院模型對(duì)實(shí)測(cè)數(shù)據(jù)進(jìn)行擬合回歸分析，計(jì)算出不同加載齡期作用下鋼筋對(duì)混凝土徐變的影響系數(shù)，并與時(shí)變函數(shù)采用CEB-FIP（1990）模型和中國建科院模型的Dischinger方法進(jìn)行了對(duì)比。 試驗(yàn)結(jié)果表明：（1）相同加載齡期的鋼筋混凝土柱徐變系數(shù)較素混凝土偏小，加載齡期對(duì)鋼筋混凝土后期徐變系數(shù)影響較少；（2）國內(nèi)外徐變預(yù)測(cè)模型對(duì)短期加載齡期（9d）的徐變系數(shù)預(yù)測(cè)精度較高，對(duì)長期加載齡期(39d)的徐變系數(shù)預(yù)測(cè)精度較差，特別是對(duì)后期徐變系數(shù)預(yù)測(cè)普遍不足，GZ（1993）（1990）模型整體預(yù)測(cè)效果較好；（3）Dischinger方法中鋼筋對(duì)混凝土徐變影響系數(shù)考慮偏低，對(duì)不同加載齡期下鋼筋混凝土徐變變形差值預(yù)測(cè)偏低。
[Abstract]:The shrinkage and creep mechanism of concrete is more complicated and the uncertain factors are many, which is one of the main causes of overdeflection in prestressed concrete bridge span.In order to improve the understanding of the influence of shrinkage and creep on the structural behavior of concrete beam bridges, this paper summarizes the long-term shrinkage and creep laws of concrete and reinforced concrete through a large number of long-term experimental studies on concrete columns and reinforced concrete cylinders.The calculation model of shrinkage and creep of concrete and reinforced concrete members is put forward, which improves the precision of predicting shrinkage and creep of concrete and reinforced concrete members.The main contents are as follows:1) through the long-term test of shrinkage strain of concrete cylinder specimen and the long-term creep test of concrete cylinder with different loading age, the long-term variation law of concrete shrinkage and creep is obtained.Based on the comparative study of the shrinkage and creep prediction models at home and abroad by using the B3 coefficient of variation and the B3 variance, a new concrete shrinkage strain prediction model is proposed, and the CEB-FIP1990) creep model is modified.(2) the creep characteristics of reinforced concrete columns are studied through a comparative test of creep of six plain concrete (reinforced concrete) columns. Combined with CEB-FIP 1990), the measured data are analyzed by fitting regression analysis with the model of China Institute of Science and Technology.The influence coefficient of reinforcement on concrete creep under different loading ages is calculated and compared with the Dischinger method of time-varying function using CEB-FIP1990) model and the model of China Institute of Science and Technology.The test results show that the creep coefficient of reinforced concrete columns with the same loading age is smaller than that of plain concrete.The effect of loading age on creep coefficient in later stage of reinforced concrete is less. 2) the prediction accuracy of creep coefficient of domestic and foreign creep prediction models is high for short-term loading age of 9 days, and poor for long term loading age of 39 days.Especially, the prediction of creep coefficient in later stage is generally insufficient. The overall prediction effect of GZ / 1993 / 1990) model is better. The influence coefficient of steel bar on creep of concrete is considered low in the method of reinforcing steel and the difference of creep deformation of reinforced concrete under different loading age is lower.
【學(xué)位授予單位】：湖南科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U441;U448.33

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