Fire Research On CFRP And Steel Strengthened RC Beams Under The Protection Of Cement Mortar

With the development of building industry in China,the research on the technology of building reinforcement has become a new trend.Among them,sticking method is the most popular one because of its economic benefits.This method includes CFRP and steel plate.However,these strengthened materials have extremely poor fire resistance,and the adhesive used for pasting cannot satisfy the need for high temperature.Nowadays,the current specifications have not given a specific method to use these reinforcing materials,especially at the high temperature.Therefore,this research focus on the fire resistance of the flexural members reinforced by the pasting method.The cement mortar protective layer which is widely used in real projects is the main fire protection measures for reinforced members.To verify the effectiveness of this measure,two reinforced beams with fire rating of three grades were designed for this study.One of them was a bonded steel plate reinforcement,and another one is for sticking carbon fiber cloth reinforcement.The reinforced beam coated with mortar was loaded at two points and subjected to an-hour-fire test in accordance with the ISO834 international standard temperature rise curve,which is to study the effect of the protective layer of cement mortar at high temperature.After the experiment,this article analyzed the bending deformation of the test beams and the changes in the temperature field through the phenomena and data.The results show that both test beams could not meet the an-hour-fire resistance limit under the effect of high temperature.During the experiment,the cement mortar failed to work early,so that the adhesive reinforcing material carbonized from the beam,and the carbon fiber cloth as well as the steel plate could not play its effective reinforcement.Based on the test results,this research used finite element analysis.The influences of different thicknesses of cement mortar on the temperature field and bending deformation of the specimens were compared.These analysis results are not only compared with the test results,but also provide reference for future application of cement mortar fire retardant coatings...