【作者】 曾在平；

【导师】 苗吉军；

【作者基本信息】 青岛理工大学 ， 结构工程， 2009， 硕士

【摘要】 混凝土是土木工程的主导材料,在北方,冬季施工的混凝土结构往往会因为防冻措施不利,浇筑后不注意保温而使混凝土受到冻害,新建土木工程尤其是混凝土结构的耐久性,在近年已经引起人们高度的重视。同时在老建筑中,由于各种原因,存在混凝土的强度偏低的情况,改造和加固工程在建筑行业中的地位也越来越重要。上世纪末兴起外贴FRP材料加固方法,FRP(Fiber ReinforcedPolymers)作为一种加固材料,以轻质、高强、无磁、良好的耐疲劳性和耐腐蚀性等显著优点越来越多的运用于土木工程中。随着FRP的广泛应用,FRP加固混凝土结构必然受到各种环境或混凝土强度偏低的影响。研究FRP加固混凝土构件整体的耐久性能具有现实意义。国内外学者对FRP加固混凝土构件的整体性能及其耐久性做了大量的试验研究,但是FRP大多集中在碳纤维(CFRP)和玻璃纤维(GFRP)等FRP上,而对性价比良好的玄武岩纤维(BFRP)加固混凝土结构的试验研究却较少。本文通过冻融循环试验,研究了冻融环境下玄武岩纤维材料和小西树脂(日本产)抗拉强度、弹性模量、延伸率等基本力学性能,玄武岩纤维与混凝土之间的正拉粘结性能,以及冻融环境作用下玄武岩加固不同强度等级(C15、C20、C30)混凝土梁的受弯试验研究,针对试验过程中出现比较频繁剥离破坏模式,提出梁跨中裂缝引起BFRP复合材料与混凝土界面间剥离极限承载力一种计算模型。本文做的主要工作如下:1、制作15个玄武岩纤维片材和15个树脂试件,分三组,每组5个试件分别经过冻融循环0次、50次、100次,研究冻融循环对玄武岩纤维材料和树脂试件基本力学性能(抗拉强度、弹性模量、延伸率)的影响。2、制作60个混凝土立方体(100×100×100)试件,研究冻融0次、25次、50次、75次不同强度等级混凝土与玄武岩纤维界面的正拉粘结性能。3、制作45根混凝土梁试件,每个强度等级的试件15根,以冻融循环次数的变化、混凝土强度等级不同、先纤维布加固后冻融和先冻融后加固等作为变化参数,研究冻融环境下采用玄武岩加固不同强度等级的钢筋混凝土梁的开裂荷载、极限承载能力以及破坏形态,分析玄武岩加固低强度混凝土试件的可行性。4、根据BFRP加固钢筋混凝土梁的几种破坏形式,分别介绍三种常见的求解极限承载力的方法。针对本次试验出现比较频繁的剥离破坏形式,提出了相应的承载力计算模型,并与试验结果进行比较,可知剥离承载力计算模型是偏于安全的,结论为工程应用提供理论依据。更多还原

【Abstract】 The concrete is the leading material of civil engineering. In the north of China, concrete frostbited because of low temperature which caused the durability of concrete structure becomes the focus now. At the same time, the question for lower concrete intensity caused by durability degeneration in the old building which needs to be strengthened is also loomed large.In the 20th centuty, the method of strengthening concrete structure with fiber reinforced plastic is developed quickly in the field of civil engineering. Fiber reinforced plastic (where briefed as FRP) is an ideal new composite material because of its lightweight, high strength and resistance to corrosion. With application widely used of FRP, the factors influenced the strengthend effects such as environment and the lower concrete intensity should be concerned, so study on durability of concrete structures strengthened with FRP is significant. Many scholars have been made large amount of experimental studies on mechanics porperties and durability for strengthening R.C. structure with CFRPand GFRP, on the contrary, few test was found for strengthening members with BFRP.In this paper, slow freeze-thaw tests were carried out for BFRP sheets and RESIN, the tensile strength, modulus of elasticity, coefficient of elongnation, cohensive strength between BFRP and concrete cubic specimen were analyzed under different cycles of freeze-thaw, the experimental researches on the flexural behaviors of concrete beams strengthened with BFRP under the enviroment of freeze-thaw were also carried out, the bearing capacity formulary was given at last according to debonding failure in the test, the main studies in this paper were shown as follows:1. The slow freeze-thaw tests were carried out for 0, 50, 100 times to fifteen BFRP specimens and fifteen resin specimens, which focused on tensile strength, modulus of elasticity, coefficient of elongation and cohensive strength.2. The slow freeze-thaw tests were carried out for 0, 25, 50, 75 times to sixty concrete cubic specimens, which focused on the cohensive performance between BFRP and concrete specimens. 3. Forty-five concret beams were fabricated, which divided into three teams according to the concrete strength. The crack loading, ultimate bearing capacities, taken into account the parametes with different cycle of freeze-thaw, concrete strength and different strengthing methods, models of failure were analyzed4. The flexural behaviors of concrete beam strengthened with BFRP were studied; three familiar calculation methods were introduced. The ultimate bearing capacity formula of debonding failure was presented according to the record of tests; the numerical calculations match a good need with the experiment results, which can be a good refrence for the same project when needs theoretical guidance.更多还原