本文選題：橋梁工程 + 徐變效應(yīng)分析　； 參考：《公路交通科技》2017年12期

【摘要】：結(jié)合在自然環(huán)境條件下開展徐變試驗(yàn)和既有研究成果,對現(xiàn)有可考慮溫度影響的徐變模型包括Fahmi提出的基于時間-溫度等效原理的徐變模型、CEB-FIP(1990)模型、BP模型、B3模型和組合徐變模型進(jìn)行比選,并將比選出的組合徐變模型應(yīng)用于預(yù)應(yīng)力混凝土梁橋的徐變效應(yīng)分析中。假定徐變符合彈性徐變理論,基于初應(yīng)變法解決了應(yīng)用組合徐變模型進(jìn)行橋梁結(jié)構(gòu)徐變效應(yīng)分析的問題。通過將基于組合徐變模型和依據(jù)我國公路04橋規(guī)分析得到的橋梁結(jié)構(gòu)變形、應(yīng)力和預(yù)應(yīng)力損失結(jié)果進(jìn)行比較,探究忽略實(shí)際變溫對徐變影響可能導(dǎo)致的橋梁結(jié)構(gòu)行為估算偏差。研究結(jié)果表明:考慮實(shí)際環(huán)境變溫影響的徐變系數(shù)預(yù)測值與試驗(yàn)值更為貼近,現(xiàn)行徐變模型因未計(jì)入環(huán)境變溫影響,可能低估了冬季和春季澆注混凝土的徐變,高估了夏季和秋季澆注混凝土的徐變;在考慮自然環(huán)境溫度影響的徐變作用下,梁體下?lián)隙瓤奢^規(guī)范值大約15.5 mm,截面應(yīng)力與規(guī)范值的最大相對偏差約為10%,預(yù)應(yīng)力損失可較規(guī)范值大約40%以上。隨機(jī)變溫作用下混凝土徐變,加劇了橋梁梁體持續(xù)下?lián)�、混凝土開裂和預(yù)應(yīng)力損失等問題。因此,在橋梁結(jié)構(gòu)設(shè)計(jì)中推薦采用組合徐變模型計(jì)入實(shí)際環(huán)境變溫對結(jié)構(gòu)混凝土徐變行為的影響,從而為預(yù)應(yīng)力束的合理布置與張拉控制、梁體預(yù)拱度的準(zhǔn)確設(shè)置等方面提供參考。
[Abstract]:Combined with the research results of creep test under natural environment, The existing creep models which can take into account the influence of temperature, including the creep model based on the time-temperature equivalence principle proposed by Fahmi (CEB-FIP / 1990), are compared with the BP model / B3 model and the combined creep model. The combined creep model selected by comparison is applied to the analysis of creep effect of prestressed concrete beam bridge. Assuming that creep is in accordance with elastic creep theory, the problem of applying combined creep model to analyze creep effect of bridge structure is solved based on initial strain method. By comparing the results of deformation, stress and prestress loss of bridge structure based on combined creep model and the analysis of highway 04 bridge gauge in China, this paper explores the estimated deviation of bridge structure behavior caused by neglecting the influence of actual temperature on creep. The results show that the predicted value of creep coefficient considering the effect of actual environmental temperature change is closer to the experimental value, and the current creep model may underestimate the creep of pouring concrete in winter and spring because it does not take into account the influence of environmental temperature change. The creep of cast concrete in summer and autumn is overestimated. The deflection under the beam can be about 15.5 mm higher than the standard value, the maximum relative deviation between the cross section stress and the normal value is about 10 mm, and the loss of prestress can be more than 40% than the normal value. Under the action of random temperature, the creep of concrete intensifies the problems of continuous deflection, cracking of concrete and loss of prestress. Therefore, in the design of bridge structure, it is recommended that the combined creep model be used to take into account the influence of temperature change in the actual environment on the creep behavior of the structure concrete, so that the reasonable arrangement and tension control of the prestressing beam can be achieved. The accurate setting of beam pre-arch is provided as a reference.
【作者單位】： 西南交通大學(xué)土木工程學(xué)院;
【基金】：國家自然科學(xué)基金項(xiàng)目(51508474) 鐵道部科技研究開發(fā)計(jì)劃重大課題項(xiàng)目(2008G031-K)
【分類號】：U441;U448.35
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本文編號：1940646