環(huán)向約束和持載下銹蝕鋼筋混凝土銹脹和粘結性能研究
發(fā)布時間：2019-05-07 11:01
【摘要】：混凝土耐久性問題是土木工程界的一個熱點問題，而鋼筋銹蝕無疑是影響鋼筋混凝土結構耐久性的主要因素。鋼筋銹蝕以后，混凝土表面會出現縱向或者橫向的裂縫、混凝土保護層脫落等現象，這些都會導致混凝土結構的承載能力降低、延性變差；混凝土和鋼筋是協同合作的，這一作用的直接體現就是粘結性能，鋼筋銹蝕以后，鋼筋混凝土之間的粘結性能會發(fā)生退化，這嚴重影響了結構的安全性。實際工程中混凝土結構都是在承受荷載條件下發(fā)生銹蝕的，而且結構中都設有箍筋作為環(huán)向約束，本文在總結已有研究成果的基礎上，考慮持載應力和新型加固材料FRP作為環(huán)向約束這兩個因素，研究其對鋼筋混凝土結構的銹脹和粘結性能的影響，這對實際工程有一定的理論價值。本文的主要研究工作如下： 對33個相同規(guī)格的試件進行了電化學加速銹蝕試驗，考慮不同持載應力、有無環(huán)向約束、不同銹蝕率等條件得到不同銹蝕條件對鋼筋混凝土結構銹脹開裂的影響；在此基礎上分析了裂縫寬度和環(huán)向應變隨著不同銹蝕條件的變化規(guī)律，，并且通過對裂縫寬度的擬合得到了鋼筋混凝土結構銹脹開裂的臨界銹蝕率。研究結果表明：隨著持載應力的增加，裂縫寬度和環(huán)向應變增大，臨界銹蝕率降低；環(huán)向約束的臨界銹蝕率高于無環(huán)向約束的臨界銹蝕率。 通過參考已有文獻關于臨界銹蝕深度的模型，考慮環(huán)向約束和持載應力這兩個因素的影響，建立了不同銹蝕條件下混凝土銹脹開裂模型，分別得到了無環(huán)向約束、無持載應力，有環(huán)向約束、無持載應力，無環(huán)向約束、有持載應力和有環(huán)向約束、有持載應力這四種條件下臨界銹蝕率的計算公式。并將理論結果和試驗結果進行了對比，驗證了該計算公式的合理性。 對銹蝕后的試件進行了拉拔試驗，考慮不同持載應力、有無環(huán)向約束、不同銹蝕率等條件得到了不同銹蝕條件對鋼筋混凝土結構銹蝕后粘結性能的影響規(guī)律；由此分析了試件的的極限粘結強度和粘結應力滑移曲線等隨著不同銹蝕條件的變化規(guī)律，并且對不同銹蝕條件下試件的極限粘結強度進行了修正。研究結果表明：環(huán)向約束影響極限粘結強度的變化；隨著持載應力的增大，有無環(huán)向約束條件下試件的滑移量和殘余粘結強度都呈現下降趨勢。
[Abstract]:The durability of concrete is a hot issue in civil engineering, and the corrosion of steel bar is undoubtedly the main factor affecting the durability of reinforced concrete structure. After the corrosion of steel bars, there will be longitudinal or transverse cracks on the concrete surface, and the concrete protective layer will fall off, which will lead to the reduction of the bearing capacity of the concrete structure and the deterioration of its ductility. Concrete and steel bar are cooperative, which is directly reflected by the bond performance. After corrosion, the bond performance between reinforced concrete will deteriorate, which seriously affects the safety of the structure. In practical engineering, concrete structures are corroded under the condition of bearing load, and there are stirrups as circumferential constraints in the structure. In this paper, based on the summary of the existing research results, Considering the bearing stress and the new reinforcement material FRP as the circumferential constraints, the influence of the two factors on the rust expansion and bond performance of reinforced concrete structures is studied. This is of theoretical value to the practical engineering. The main research work in this paper is as follows: electrochemical accelerated corrosion tests were carried out on 33 specimens of the same size, considering the different load-holding stresses, whether or not there is a circumferential constraint. The influence of different corrosion conditions on the corrosion bulging and cracking of reinforced concrete structures is obtained under different corrosion rates and other conditions. On this basis, the variation rule of crack width and circumferential strain with different corrosion conditions is analyzed, and the critical corrosion rate of corrosion expansion cracking of reinforced concrete structure is obtained by fitting the crack width. The results show that the critical corrosion rate decreases with the increase of the holding stress, and the critical corrosion rate of the circumferential constraint is higher than that of the uncircumferential constraint, and the crack width and the circumferential strain increase and the critical corrosion rate decreases with the increase of the holding stress. By referring to the existing models of critical corrosion depth and considering the influence of circumferential constraint and holding stress, the corrosion expansion and cracking models of concrete under different corrosion conditions are established, and no circumferential constraint and no supporting stress are obtained, respectively. The formula of critical corrosion rate under four conditions: circumferential constraint, no holding stress, no circumferential constraint, bearing stress and circumferential constraint, and holding stress, is the formula for calculating the critical corrosion rate under the conditions of circumferential constraint, no holding stress, no annular constraint, and no cyclic constraint. The theoretical results are compared with the experimental results, and the rationality of the formula is verified. The tensile test of corroded specimens was carried out. The influence of different corrosion conditions on the bond properties of corroded reinforced concrete structures was obtained under the conditions of considering different load-holding stresses, circumferential constraints and different corrosion rates. The variation rules of the ultimate bond strength and bond stress-slip curve with different corrosion conditions are analyzed, and the ultimate bond strength of the specimen under different corrosion conditions is modified. The results show that circumferential constraint affects the change of ultimate bond strength, and the slip amount and residual bond strength of specimens with or without circumferential constraints decrease with the increase of load-holding stress.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU375
[Abstract]:The durability of concrete is a hot issue in civil engineering, and the corrosion of steel bar is undoubtedly the main factor affecting the durability of reinforced concrete structure. After the corrosion of steel bars, there will be longitudinal or transverse cracks on the concrete surface, and the concrete protective layer will fall off, which will lead to the reduction of the bearing capacity of the concrete structure and the deterioration of its ductility. Concrete and steel bar are cooperative, which is directly reflected by the bond performance. After corrosion, the bond performance between reinforced concrete will deteriorate, which seriously affects the safety of the structure. In practical engineering, concrete structures are corroded under the condition of bearing load, and there are stirrups as circumferential constraints in the structure. In this paper, based on the summary of the existing research results, Considering the bearing stress and the new reinforcement material FRP as the circumferential constraints, the influence of the two factors on the rust expansion and bond performance of reinforced concrete structures is studied. This is of theoretical value to the practical engineering. The main research work in this paper is as follows: electrochemical accelerated corrosion tests were carried out on 33 specimens of the same size, considering the different load-holding stresses, whether or not there is a circumferential constraint. The influence of different corrosion conditions on the corrosion bulging and cracking of reinforced concrete structures is obtained under different corrosion rates and other conditions. On this basis, the variation rule of crack width and circumferential strain with different corrosion conditions is analyzed, and the critical corrosion rate of corrosion expansion cracking of reinforced concrete structure is obtained by fitting the crack width. The results show that the critical corrosion rate decreases with the increase of the holding stress, and the critical corrosion rate of the circumferential constraint is higher than that of the uncircumferential constraint, and the crack width and the circumferential strain increase and the critical corrosion rate decreases with the increase of the holding stress. By referring to the existing models of critical corrosion depth and considering the influence of circumferential constraint and holding stress, the corrosion expansion and cracking models of concrete under different corrosion conditions are established, and no circumferential constraint and no supporting stress are obtained, respectively. The formula of critical corrosion rate under four conditions: circumferential constraint, no holding stress, no circumferential constraint, bearing stress and circumferential constraint, and holding stress, is the formula for calculating the critical corrosion rate under the conditions of circumferential constraint, no holding stress, no annular constraint, and no cyclic constraint. The theoretical results are compared with the experimental results, and the rationality of the formula is verified. The tensile test of corroded specimens was carried out. The influence of different corrosion conditions on the bond properties of corroded reinforced concrete structures was obtained under the conditions of considering different load-holding stresses, circumferential constraints and different corrosion rates. The variation rules of the ultimate bond strength and bond stress-slip curve with different corrosion conditions are analyzed, and the ultimate bond strength of the specimen under different corrosion conditions is modified. The results show that circumferential constraint affects the change of ultimate bond strength, and the slip amount and residual bond strength of specimens with or without circumferential constraints decrease with the increase of load-holding stress.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TU375
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