本文選題：CFRP加固 + 局部薄弱��； 參考：《大連理工大學(xué)》2015年博士論文

【摘要】：鋼筋混凝土柱的質(zhì)量受施工及環(huán)境因素影響較大,如施工期間混凝土振搗和養(yǎng)護(hù)不足、服役期間經(jīng)受凍融循環(huán)等情況都可能造成柱中局部混凝土的劣化。在實(shí)際工程中,上述因素導(dǎo)致的局部薄弱柱較為常見,且不易被人們直觀地察覺,這會給整體結(jié)構(gòu)安全埋下隱患,甚至可能在地震中發(fā)生嚴(yán)重的事故�，F(xiàn)代建筑檢測技術(shù)的發(fā)展,使得人們可以更容易通過檢測設(shè)備發(fā)現(xiàn)柱中局部薄弱混凝土的存在并及時(shí)采取措施進(jìn)行加固。碳纖維增強(qiáng)復(fù)合材料(CFRP)以其輕質(zhì)高強(qiáng)、防腐等優(yōu)勢,近年來成為鋼筋混凝土加固領(lǐng)域主要的材料之一。各國研究人員已經(jīng)對FRP加固鋼筋混凝土柱的抗震性能進(jìn)行了大量的試驗(yàn)與理論研究,并取得了諸多成果。本文在前人研究的基礎(chǔ)上,對CFRP加固局部薄弱柱的抗震性能進(jìn)行了試驗(yàn)、有限元及理論分析,并研究了局部薄弱混凝土對柱承載力及延性的影響,以及CFRP對局部薄弱柱抗震性能的修復(fù)效果,進(jìn)而提出了加固局部薄弱柱所需CFRP用量的計(jì)算方法。本文主要的研究內(nèi)容如下：(1)首先分別對1個(gè)方截面薄弱柱及非薄弱對比柱、2個(gè)圓截面薄弱柱、1個(gè)圓截面非薄弱對比柱以及3個(gè)圓截面加固薄弱柱進(jìn)行了擬靜力試驗(yàn)。試驗(yàn)結(jié)果表明：當(dāng)局部薄弱混凝土位于柱根時(shí),會對柱的極限承載力、延性造成不利的影響。CFRP加固可以有效地改變局部薄弱柱的破壞形態(tài),顯著提高局部薄弱柱的延性及耗能能力,并且可基本恢復(fù)薄弱柱的極限承載力,延緩局部薄弱柱縱向鋼筋的屈服及剛度的衰減；(2)基于有限元軟件OpenSees,采用纖維有限元模型,對上述試件的滯回曲線進(jìn)行了預(yù)測,并通過參數(shù)分析,對48種不同工況局部薄弱柱的滯回曲線進(jìn)行了模擬分析,研究了當(dāng)局部薄弱混凝土位于柱根時(shí),軸壓比、長細(xì)比以及CFRP厚度對局部薄弱柱抗震性能的影響。研究表明：CFRP對局部薄弱柱的抗震加固效果隨軸壓比及CFRP厚度的增大而逐漸增大,隨長細(xì)比的增加而逐漸減�。�(3)基于有限元軟件ABAQUS,采用三維有限元模型,對試件進(jìn)行了數(shù)值模擬,預(yù)測了各試件的滯回曲線、破壞位置及破壞形態(tài),并通過對42種不同工況的局部薄弱柱的破壞形態(tài)及滯回曲線進(jìn)行預(yù)測,研究了不同位置的薄弱混凝土對局部薄弱柱的影響,進(jìn)而提出了地震中局部薄弱柱破壞位置的判別方法。研究表明：地震作用下局部薄弱柱的破壞發(fā)生在柱根及薄弱區(qū)兩個(gè)區(qū)域之一,其發(fā)生初始破壞的位置同局部薄弱柱的級差率、軸壓比以及薄弱區(qū)位置有關(guān)。CFRP對局部薄弱柱承載力的加固效果與薄弱區(qū)混凝土強(qiáng)度、CFRP厚度及拉伸強(qiáng)度有關(guān)；(4)基于文獻(xiàn)中實(shí)測的FRP約束混凝土應(yīng)力-應(yīng)變曲線,提出了一個(gè)新的FRP約束混凝土應(yīng)力-應(yīng)變關(guān)系分析模型,并基于平截面假定,采用該模型以及約束混凝土軸壓設(shè)計(jì)模型、約束混凝土偏壓設(shè)計(jì)模型,對壓彎狀態(tài)下CFRP加固局部薄弱柱的荷載-位移曲線進(jìn)行了預(yù)測。研究表明：本文所提的FRP約束混凝土分析模型計(jì)算簡便、且精度較高。當(dāng)軸壓比、長細(xì)比較大、約束混凝土強(qiáng)度較低、CFRP厚度較大時(shí),使用偏壓應(yīng)力-應(yīng)變關(guān)系預(yù)測的荷載-位移曲線更為準(zhǔn)確。
[Abstract]:The quality of reinforced concrete columns is greatly influenced by the construction and environmental factors. For example, concrete vibration and maintenance are insufficient during construction, and the conditions of freezing and thawing during service may cause the deterioration of the concrete in the column. In practical engineering, the local weak columns caused by these factors are more common and are not easily detected by people. The development of modern building detection technology makes it easier for people to detect the existence of weak concrete in the column and take measures to reinforce it in time. Carbon fiber reinforced composites (CFRP), with its lightweight, high strength and anticorrosion, can be found more easily. In recent years, it has become one of the main materials in the field of reinforced concrete reinforcement. Many researchers have done a lot of experiments and theoretical studies on the seismic performance of reinforced concrete columns reinforced by FRP, and have made many achievements. On the basis of previous studies, this paper tries to test the seismic performance of a local weak column reinforced by CFRP. The effect of the local weak concrete on the bearing capacity and the ductility of the column and the effect of CFRP on the seismic performance of the local weak columns are studied, and the calculation method of the amount of CFRP for strengthening the local weak columns is proposed. The main contents of this paper are as follows: (1) first of all 1 square columns and weak columns respectively. Non weak contrast column, 2 circular cross section weak column, 1 circular cross section non weak contrast column and 3 circular cross section reinforced weak column are tested. The test results show that when the local weak concrete is located at the root of the column, the ultimate bearing capacity of the column, the ductility caused by the adverse effect of.CFRP reinforcement can effectively change the local weak column. The failure mode can significantly improve the ductility and energy dissipation capacity of the local weak column, and can basically restore the ultimate bearing capacity of the weak column, postpone the yield and stiffness attenuation of the longitudinal reinforcement of the local weak column. (2) based on the finite element software OpenSees, the fiber finite element model is used to predict the hysteresis curve of the above specimens and through the parameters. The hysteretic curves of local weak columns in 48 different working conditions are simulated and analyzed. The effects of axial compression ratio, length to length ratio and CFRP thickness on the seismic performance of local weak columns are studied when the local weak concrete is located at the root of the column. The study shows that the effect of CFRP on the local weak columns increases with the ratio of axial pressure and the thickness of CFRP to the local weak columns. Gradually, it gradually decreases with the increase of slenderness ratio; (3) based on the finite element software ABAQUS, the three-dimensional finite element model is used to simulate the specimen, the hysteretic curve, the failure position and the failure form of the specimens are predicted, and the failure mode and hysteresis curve of the weak columns in the 42 different working conditions are predicted. The influence of the weak concrete in different positions on the local weak column is investigated, and the method of judging the failure position of the local weak column in the earthquake is put forward. The study shows that the damage of the local weak column is one of the two regions of the column root and the weak area under the earthquake action, and the initial broken position is the same as the difference of the local weak column and the axial pressure. The reinforcement effect of.CFRP on the bearing capacity of the local weak column is related to the strength of concrete in the weak zone, the thickness of CFRP and the tensile strength of the weak region. (4) a new stress strain relationship analysis model of the concrete constrained concrete is proposed based on the measured FRP stress strain curve in the literature, and it is based on the assumption of the flat section. By using the model and constrained concrete axial compression design model, the load displacement curve of the local weak column strengthened by CFRP is predicted by constrained concrete bias design model. The study shows that the FRP constrained concrete analysis model proposed in this paper is simple and accurate. When the strength of the aggregate is low and the thickness of CFRP is large, the load displacement curve predicted by using the biaxial stress-strain relationship is more accurate.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TU375.3;TU352.11
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本文編號：2042188