Experimental Study On Fire Resistance Of RC Beams And Columns Strengthened With Angle Steel

Reinforced concrete structure is the widest structural form that used in building.But more and more problems such as building ageing or functional changing lead to more and more strengthening to reinforced concrete members.Angle steel reinforcing is an effective,economical and easily applied strengthening method which was one of the widest used strengthening methods for RC(reinforced concrete)structure.However,there is no provision in Chinese codes specific to the fire resistance of ASSRC(Angle Steel Strengthening Reinforced Concrete)beams or columns.Only a rough rule was given by "Code for design of strengthening concrete structure" which regulate the cement fire protection thickness must be 25 mm at least.According to these conditions,this paper has carried out a series of experiments and simulations on fire resistance of ASSRC beams and columns.The main research work in this dissertation was outlined as follows:Experiments of 4 ASSRC beams and 4 ASSRC columns have been carried out.The inflammability,temperature field distribution of cross-section,fire resistance and failure pattern of each specimen has been obtained.Meanwhile,longitudinal displacement of top,rotation of top and lateral displacement of middle as a function of time have been achieved in the experiments of ASSRC columns.And mid-span deflection as a function of time has been achieved in the experiments of ASSRC beams.ASSRC beams and columns were modeled to do fire-structure coupling analysis using ABAQUS,which was validated using some experimental test data.Considering the influence of cement flaking off,grouting gap retarding heat transfer and epoxy resin failure,the finite element models analyzed the effect of load level,increasing coefficient of carrying capacity and thickness of cement fire protection on fire resistance of ASSRC beam;and the effect of load level,eccentricity ratio,increasing coefficient of carrying capacity and thickness of cement fire protection on fire resistance of ASSRC column.Based on the analysis of finite element models,this paper provided simplify equations to calculate the fire resistance of ASSRC column and beam,and the equations of cement protection thickness have been derivated.