无机胶粘贴CFRP布加固梁火灾后受力性能试验

Experimental research on mechanical performance of reinforced concrete beams strengthened with CFRP sheets bonded with an inorganic adhesive after fire

目前粘贴碳纤维(CFRP)布加固混凝土结构多采用环氧类有机胶,但其软化温度过低,多为60～80℃,用环氧类有机胶粘贴CFRP布加固混凝土结构难以满足耐高温要求.为此,研发了600℃时强度不低于常温强度的无机胶,并用其粘贴CFRP布加固混凝土梁.对4根已进行过火灾下耐火性能试验的加固梁进行火灾后受力性能试验,描述加固梁火灾后受力破坏过程,获得了火灾后受弯承载力试验值和荷载-跨中位移变形曲线,进行了受弯承载力分析,提出正截面承载力计算公式和构件刚度计算方法.试验与分析表明,当CFRP布历经的温度高于300℃时,CFRP布的强度不能充分利用,加固性能有所下降.相关公式计算值与试验结果吻合较好,可用于该类加固梁火灾后正截面承载力和构件刚度的计算.

The organic epoxy adhesive usually used in the concrete structures strengthened with CFRP sheets has low softening temperatures of 60 -80 ℃ and it is difficult to meet the requirement of fire endurance, there-fore, an inorganic adhesive is developed and used to bond CFRP sheets to strengthen concrete beams, whose strength at 600℃ is not lower than that at normal room temperature. Experiments on mechanical properties of four strengthened beams that experienced fire test were completed. The flexural failure processes of beams were observed. Flexural carrying capacity of these beams and the load -displace curves at the mid -span were obtained. Flexural carrying capacity was analyzed. The calculation formula of flexural carrying capacity and the calculation method of stiffness were presented. The experimental and analysis results show that the strength of CFRP sheets bonded with the inorganic adhesive can not be played fully when the temperature CFRP sheets experienced is above 300 ℃ in fire. The calculation values of formula are in good agreement with test results. The formula can be used for computing flexural carrying capacity and stiffness of this kind of beam.