【摘要】：鋼筋混凝土結(jié)構(gòu)是世界上使用最為廣泛的結(jié)構(gòu)形式之一,目前已成功應(yīng)用于工業(yè)與民用建筑、橋梁、隧道、礦井、水利及海港等工程中。由于混凝土結(jié)構(gòu)所用材料及所處環(huán)境的特點(diǎn),使得混凝土結(jié)構(gòu)不可避免地會(huì)出現(xiàn)開裂、性能劣化,最終產(chǎn)生耐久性問題。鋼筋銹蝕會(huì)導(dǎo)致鋼筋混凝土材料物理和化學(xué)性質(zhì)的變化,并將最終影響鋼筋混凝土構(gòu)件的力學(xué)行為,鋼筋銹蝕導(dǎo)致的混凝土構(gòu)件力學(xué)性能退化是一個(gè)極其復(fù)雜的過程,如何評(píng)定不同銹蝕程度下混凝土構(gòu)件的承載能力和延性等力學(xué)性能的改變具有重要的意義,但是目前關(guān)于導(dǎo)致鋼筋銹蝕的劣化因素與混凝土構(gòu)件力學(xué)性能改變之間的定量關(guān)系研究仍不足。故研究混凝土結(jié)構(gòu)的破壞問題,特別是混凝土結(jié)構(gòu)中的裂縫問題以及環(huán)境引起的混凝土結(jié)構(gòu)耐久性問題十分有意義。以此為主線,基于擴(kuò)展有限元與粘聚力模型研究了混凝土梁的受剪破壞過程,以及銹蝕混凝土梁受剪承載能力的變化情況。主要研究工作如下： (1)基于擴(kuò)展有限元法對(duì)混凝土梁剪壓破壞進(jìn)行了分析研究。嘗試將擴(kuò)展有限元法應(yīng)用到鋼筋混凝土梁的受剪破壞分析中,分析結(jié)果與已有研究吻合較好；基于混凝土受拉開裂的雙折線模型推導(dǎo)出了粘聚力隨裂縫張開位移的指數(shù)下降模型,更加符合混凝土開裂的實(shí)際情況；證明了擴(kuò)展有限元法的適用性,可在分析混凝土構(gòu)件的開裂問題中進(jìn)一步推廣應(yīng)用； (2)根據(jù)法拉第定律設(shè)計(jì)了三種不同銹蝕率的試件,對(duì)銹蝕鋼筋混凝土梁進(jìn)行了受剪破壞試驗(yàn)。觀測(cè)了鋼筋銹蝕引起混凝土保護(hù)層開裂的形式及裂縫寬度,研究了鋼筋銹蝕對(duì)混凝土梁斜裂縫的形成、開展及構(gòu)件承載性能等方面的影響,并通過回歸擬合得到了銹蝕混凝土梁受剪承載力的計(jì)算公式； (3)基于粘聚力模型,給出了銹蝕鋼筋與混凝土間粘結(jié)-滑移的本構(gòu)模型,計(jì)算得出了不同銹蝕率下混凝土梁的承載能力變化,并與試驗(yàn)結(jié)果進(jìn)行了對(duì)比分析,表現(xiàn)出了良好的一致性,證明本模型能夠很好地描述鋼筋-混凝土界面的粘結(jié)-滑移關(guān)系。另外,還進(jìn)行了參數(shù)分析,得到了模型參數(shù)對(duì)混凝土粱承載能力的影響規(guī)律,從界面層面上解釋了鋼筋銹蝕引起構(gòu)件性能變化的原因。最后分析了鋼筋縱向粘結(jié)強(qiáng)度非均勻分布的影響,證明了本模型的可擴(kuò)展性。
[Abstract]:Reinforced concrete structure is one of the most widely used structures in the world. It has been successfully used in industrial and civil construction, bridges, tunnels, mines, water conservancy and seaports. Due to the characteristics of the material and environment used in concrete structure, it is inevitable that the concrete structure will crack, the performance will deteriorate, and finally the durability problem will occur. The corrosion of steel bars will lead to the change of physical and chemical properties of reinforced concrete materials, and will ultimately affect the mechanical behavior of reinforced concrete members. The degradation of mechanical properties of reinforced concrete members caused by steel corrosion is an extremely complex process. How to evaluate the change of mechanical properties such as bearing capacity and ductility of concrete members with different corrosion degree is of great significance. However, the quantitative study on the relationship between the deterioration factors and the mechanical properties of concrete members is still insufficient. Therefore, it is of great significance to study the damage of concrete structures, especially the cracks in concrete structures and the durability of concrete structures caused by environment. Based on the extended finite element method and cohesive force model, the shear failure process of concrete beams and the variation of shear bearing capacity of corroded concrete beams are studied. The main research work is as follows: (1) the shear-compression failure of concrete beams is studied based on the extended finite element method. The extended finite element method is applied to the shear failure analysis of reinforced concrete beams, and the results are in good agreement with the previous studies. Based on the double broken line model of concrete tensile cracking, the exponential decreasing model of cohesion force with crack opening displacement is derived, which is more in line with the actual situation of concrete cracking, and proves the applicability of the extended finite element method. It can be further applied in the analysis of cracking of concrete members. (2) three specimens with different corrosion rates are designed according to Faraday's law, and the shear failure tests of corroded reinforced concrete beams are carried out. The form and width of cracking in concrete cover caused by steel corrosion are observed, and the influence of steel corrosion on the formation, development and bearing capacity of concrete beams is studied. The formula of shear capacity of corroded concrete beams is obtained by regression fitting. (3) based on the cohesive force model, a constitutive model of bond slip between corroded steel bar and concrete is given. The load-bearing capacity of concrete beams with different corrosion rates is calculated and compared with the experimental results. The results show good agreement. It is proved that the model can describe the bond-slip relationship between reinforcement and concrete interface well. In addition, the influence of the model parameters on the bearing capacity of concrete beam is obtained by parameter analysis, and the reason of the behavior change caused by the corrosion of steel bar is explained from the interface level. Finally, the influence of non-uniform distribution of longitudinal bond strength is analyzed, and the extensibility of the model is proved.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU375

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