【作者】 张婷婷；

【导师】 张鑫；

【作者基本信息】 山东建筑大学 ， 结构工程， 2011， 硕士

【摘要】 随着经济的发展,我国的土建行业已经逐渐由“建造”转为“维护、加固”阶段,在众多加固方法中,粘贴碳纤维布(CFRP)加固混凝土构件的方法因碳纤维布轻质高强、耐腐蚀等优点而得到越来越广泛的应用。目前用于粘贴碳纤维布的粘剂大多为环氧树脂类有机胶,但是,这些有机胶玻璃转化温度一般较低,在65℃～150℃之间,在较高温度或者火灾下很容易失去粘结强度,致使碳纤维布脱落从而失去加固效果。针对这个问题,本课题通过试验,使用无机胶凝材料MOC(以下简称MOC)替代有机胶粘贴碳纤维布加固混凝土梁并进行耐高温试验,研究无机胶MOC粘帖碳纤维布加固混凝土梁的抗高温性能。本试验所使用的无机胶MOC的主要成分是氯化镁、氧化镁和硅微粉,其在常温下的力学性能除抗弯强度稍逊于环氧树脂类有机胶,其它力学性能均不低于环氧树脂类有机胶。本文通过外表没有采取防火保护的MOC试块高温后的抗压及抗折试验,研究了MOC的耐高温性能,拟合了MOC试块高温后抗压及抗折强度与煅烧温度关系的表达式。试验结果表明在200℃内该胶的抗压强度几乎不降低,反而有一些升高,温度超过250℃以后,强度陡然下降,达到350℃时的抗压强度仅约为常温时的59.74%,温度超过400℃时该胶完全破坏。通过外表采取防火保护的MOC试块的耐高温试验,研究了防火涂料的防护效果以及MOC的耐高温性能,试验结果表明在400℃的高温下,有防火保护的MOC试块仍然有很高的抗压强度,比未加防火保护的MOC试块提高了4.68倍,由此可见采取有效的防火保护可以显著减少无机胶MOC抗压强度的损失。本文还对1根采取防火保护并使用有机胶粘贴碳纤维布加固的混凝土简支梁、1根采取防火保护并使用无机胶MOC粘贴碳纤维布加固的混凝土简支梁以及1根不采取防火保护使用无机胶粘贴碳纤维布加固的混凝土简支梁进行高温试验研究,试验结果表明在有防火保护的情况下,有机胶、无机胶粘贴混凝土梁的截面温度场变化规律基本一致,证明两者在高温下的导热性能基本相同,但是,有机胶粘贴的碳纤维布在试验后已经烧成丝状,与混凝土剥离,证明有机胶已经失效,而无机胶粘结的碳纤维布在试验后基本没有剥离破坏,胶层尚有一定的粘结强度,证明无机胶具有较好的耐高温性能。同时,有机胶粘贴碳纤维布加固混凝土梁的跨中挠度达到无机胶粘贴碳纤维布加固混凝土梁的1.5倍,表明无机胶有更好的耐高温性能。对比无机胶粘贴碳纤维布加固混凝土梁有无防火涂料的试验结果表明,没有防火涂料的混凝土梁的截面温度、表层温度以及内部钢筋温度的升高速度、最大值都大大高于涂有防火涂料的混凝土梁,证明了防火涂料对混凝土良好的高温保护作用。同时,没有防火保护的混凝土梁的跨中挠度达到有防火保护的混凝土梁的13.8倍,大大超过了临界值,已经丧失工作能力,而无机胶加固混凝土梁的挠度尚在临界范围之内。更多还原

【Abstract】 With the development of economy, the civil industry of our country is changing gradually from the stage of ’build’to’maintain and reinforce’. In numerous methods of structural reinforcing, the method of bonding the concrete and CFRP (carbon fiber reinforced polymer) using glues is being used widely and widely due to the lightweight high strength and corrosion resistance of CFRP. At present, the glues used are mainly organic epoxy resin, whose transformation temperature to glass is relatively low (65℃～150℃), resulting that the bonding strength of glues is easily lost in fires and the CFRP is easy to fall off from the concrete. According to this problem, this paper conducted a study on the high temperature behavior of RC beams strengthened with CFRP by inorganic paste through a series of laboratory tests.The main components of the inorganic paste MOC used in this study are magnesium chloride, magnesia and silica powder. Its mechanical properties at ordinary temperature are similar with the organic paste except that the flexural strength is a little lower. Through compression and transverse tests on the MOC blocks without fire protection which have been burned under high temperatures, this paper makes a study on the high temperature behavior of MOC and obtained a relationship between the compression and flexural strength and the burning temperatures. Test results showed that the compression strength of MOC blocks does not decrease within 200℃,but increases a little. However, when the burning temperature exceeds 200℃, the compression strength drops suddenly, e.g., it is only 59.74% of the compression strength at normal temperature when the burning temperature is 300℃and the MOC blocks have been totally destroyed when the burning temperature reaches 400℃. Through compression and transverse tests on the MOC blocks with fire protection which have been burned under high temperatures, this paper makes a study on fire resistance of refractory coating. Test results showed that the compression strength at 400℃for the MOC blocks with fire protection is 4.68 times as the strength without fire protection, proving the effect of fire resistance using refractory coating.Then, through transverse tests on three RC beams which is bonded using inorganic paste with fire protection, bonded using inorganic paste without fire protection and bonded using organic paste with fire protection respectively, this paper makes a study on the high temperature behavior of RC beams strengthened with CFRP by inorganic paste. Comparison between test results of RC beams which is bonded using inorganic paste with fire protection and bonded using organic paste with fire protection showed that the temperature field of RC sections are similar, indicating that the heat conduction performance of the two pastes is similar. However, the CFRP of RC beams using organic paste has been burned to be filamentous after the test and has fall off the concrete, besides that the CFRP using inorganic paste still stick to the concrete, proving that the performance of fire resistance of inorganic paste is better than that of organic paste. Moreover, the midspan deflection of RC beams using organic paste is 1.5 times as that using inorganic paste. Comparison between test results of RC beams which is bonded using inorganic paste with fire protection and bonded using inorganic paste without fire protection showed that the temperatures of RC sections, RC surfaces and steels without fire protection are all much higher than that with fire protection, indicating that the fire resistance of refractory coating. Moreover, the midspan deflection of RC beams without fire protection is 13.8 times as that with fire protection and has exceeded the limited value, besides that the RC beams with fire protection could still work.更多还原