本文選題：CFRP約束混凝土 + 混凝土徐變和收縮��； 參考：《西南交通大學(xué)》2015年碩士論文

【摘要】：FRP (Fiber Reinforced Plastics)約束混凝土可以有效的提高混凝土柱的強(qiáng)度和延性,在過去的幾十年中,雖然國內(nèi)外學(xué)者對短期荷載作用下FRP約束混凝土的力學(xué)性能展開了較為深入的研究,但實(shí)際工程中的混凝土柱在進(jìn)行FRP約束加固之前已經(jīng)產(chǎn)生了較大的變形,在加固之后又要經(jīng)歷長期荷載作用,故要更好的預(yù)測實(shí)際工程中FRP約束混凝土的長期使用性能,有必要對長期荷載作用下FRP約束混凝土的力學(xué)性能進(jìn)行研究。混凝土和FRP在長期荷載作用下會(huì)發(fā)生徐變現(xiàn)象,想要較為準(zhǔn)確的對長期荷載作用下FRP約束混凝土的力學(xué)性能進(jìn)行模擬,有必要對：(1)混凝土的徐變、收縮性能；(2)FRP的徐變性能；(3)短期荷載作用下FRP約束混凝土的力學(xué)性能進(jìn)行研究,本文按照以上思路,主要研究了以下幾點(diǎn)內(nèi)容：首先,根據(jù)RILEM試驗(yàn)數(shù)據(jù)庫,對四種常見的混凝土徐變、收縮預(yù)測模型進(jìn)行了對比,發(fā)現(xiàn)GL2000模型與B3模型具有相對較高的準(zhǔn)確性,其中GL2000模型更加適用于數(shù)值模擬分析；根據(jù)收集到的CFRP (Carbon Fiber Reinforced Plastics)徐變數(shù)據(jù),對Findley模型進(jìn)行了修正,得到了適用于CFRP片材的徐變模型。其次,對短期荷載作用下CFRP約束混凝土進(jìn)行了數(shù)值模擬,將模擬結(jié)果與試驗(yàn)結(jié)果對比后發(fā)現(xiàn)：(1)文中使用的增量迭代法能夠較為準(zhǔn)確的模擬CFRP約束混凝土的應(yīng)力—應(yīng)變曲線關(guān)系；(2)CFRP約束混凝土的軸向—側(cè)向應(yīng)變關(guān)系對模擬結(jié)果影響較大,在收集到的軸向—側(cè)向應(yīng)變關(guān)系計(jì)算表達(dá)式中,Teng J G公式具有相對較高的準(zhǔn)確性。最后,將混凝土徐變、收縮模型,CFRP徐變模型以及短期荷載作用下CFRP約束混凝土的數(shù)值模擬程序結(jié)合到一起,可以完成長期荷載作用下CFRP約束混凝土的MATLAB編程模擬,模擬結(jié)果表明：(1)在不提高軸向持荷水平的前提下,實(shí)際加固中FRP片材的使用效率較低,CFRP片材所能提供的側(cè)向約束力通常只有極限側(cè)向約束力的20%到30%左右；(2)由于側(cè)向約束力較小,長期荷載作用下CFRP約束混凝土的軸向應(yīng)變—時(shí)間關(guān)系與普通混凝土構(gòu)件的軸向應(yīng)變—時(shí)間關(guān)系相差不大,基本上符合GL2000模型的預(yù)測結(jié)果；(3)徐變會(huì)造成CFRP片材的彈性模量增加,但極限拉應(yīng)變降低,這會(huì)對長期荷載作用后CFRP約束混凝土的力學(xué)性能造成一定影響,通過數(shù)值模擬可以發(fā)現(xiàn),在長期荷載作用后CFRP約束混凝土的峰值應(yīng)力基本沒有發(fā)生變化,但峰值應(yīng)變降低較為明顯,這會(huì)影響到CFRP約束混凝土的在長期使用過程中的延性。
[Abstract]:FRP fiber reinforced plastic (FRP) confined concrete can effectively improve the strength and ductility of concrete columns. In the past few decades, although the mechanical properties of FRP confined concrete under short term loads have been studied deeply by domestic and foreign scholars. However, concrete columns in practical engineering have already produced large deformation before FRP restrained reinforcement and have to undergo long-term load after strengthening. Therefore, it is necessary to better predict the long-term performance of FRP confined concrete in practical engineering. It is necessary to study the mechanical properties of FRP confined concrete under long-term load. The creep of concrete and FRP will occur under long term load. In order to simulate the mechanical behavior of FRP confined concrete under long term load, it is necessary to study the creep of concrete. The mechanical properties of FRP confined concrete under short term load are studied. According to the above ideas, the following contents are mainly studied in this paper: firstly, according to the RILEM test database, the mechanical properties of FRP confined concrete are studied. Four kinds of common concrete creep and shrinkage prediction models are compared. It is found that GL2000 model and B3 model have relatively high accuracy, and GL2000 model is more suitable for numerical simulation analysis, and according to the collected CFRP carbon fiber reinforced plastic data, Findley model is modified and a creep model suitable for CFRP sheet is obtained. Secondly, the CFRP confined concrete is numerically simulated under short term load. Comparing the simulation results with the experimental results, it is found that the incremental iterative method used in this paper can simulate the stress-strain curve relationship of CFRP-confined concrete accurately. The axial to lateral strain relationship of CFRP-confined concrete has a great influence on the simulation results. Teng J G formula is relatively accurate in the collected expressions of axial lateral strain relationship. Finally, by combining concrete creep, shrinkage model with CFRP creep model and numerical simulation program of CFRP confined concrete under short term load, MATLAB programming simulation of CFRP confined concrete under long term load can be completed. The simulation results show that: 1) without increasing the axial load holding level, In practical reinforcement, FRP sheets can provide only about 20% to 30% of the ultimate lateral binding force due to the low efficiency of using CFRP sheets) because of the smaller lateral binding force, the FRP sheet can provide only about 20% to 30% of the ultimate lateral binding force. The axial strain-time relationship of CFRP-confined concrete under long-term loading is not different from that of ordinary concrete members. The creep of CFRP-confined concrete will increase the elastic modulus of CFRP sheets, which is basically consistent with the prediction result of GL2000 model. However, the reduction of ultimate tensile strain will have a certain effect on the mechanical properties of CFRP-confined concrete after long term load. Through numerical simulation, it can be found that the peak stress of CFRP-confined concrete basically does not change after long term load. However, the decrease of peak strain is obvious, which will affect the ductility of CFRP-confined concrete during long term service.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU528

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本文編號(hào)：2006249