The Research And Application On Fire-resistant And Fire Retardant Coating Of Reinforced Concrete Beam

Reinforced concrete structure an excellent building structure form, has suchadvantages as good durability, integrity, plasticity and saving steels, and is widelyused in our industrial or civil architectures. However, the building fires have occurredfrequently in recent years, and various fires have brought about immeasurable lossesto people’s lives and properties. In high temperature fires, concrete will burst, and thematerial strength of the steel will be reduced remarkably; the material strength andmechanical property of the reinforced concrete structure will vary considerably;deformation will be increased obviously; the volume of the component will beexpanded and the temperature distribution of the section will not be uniform, so thatthe section will generate self-equilibrium temperature stress and member bendingdeformation to destroy the structural system. Therefore, the knowledge about thestrength and deformation rule of the reinforced concrete member at high temperatureand the analysis and calculation of the temperature field of RC beams at the hightemperature of a fire is very important to the study on the fire retardant coatingprotection of the concrete structure in the fire.The main tasks of this paper are asfollows:(1) Study and analyze the thermal and mechanical properties of the concrete andthe reinforcing bar at high temperature; carry out material tests on the cubecompressive strength of concrete at high temperature; heat several groups of concretesamples within several temperature ranges, observe and record the appearance changeof the concrete; carry out compressive strength tests of concrete materials aftercooling, and work out the rule of the changes in the appearance features andcompressive strengths of the concrete samples within different temperature ranges;(2) Carry out a series of theoretical analysis on the heat conduction equation anddefinite conditions of the RC beam with the follownig results:The integrated heat transfer coefficient of the member surface is affected by thetemperature of the fire field and the surface temperature of the member, and thethermal performance parameter of the building material is the function of temperature.Classify the boundary conditions into three types according to the characteristics onheat transfer interaction between the medium surface and the surrounding mediums,and work out the temperature function for each boundary condition; (3) Program by using MATLAB if three sides of the concrete member areuniformly exposed to fire simultaneously, and simulate the whole process of heattransfer and deformation in the member to analyze and study on the change process ofthe temperature field in the member and the structure with the fire going on, as well asthe rest bearing force of the beam after the fire;(4) Carry out high temperature tests on the concrete with fire retardant coatingby the using SQW-A High Temperature Strength Tester to discover the protectionfunction of the fire retardant coatings on the fireproof performance of the concretestructure. The experimental study shows that the compressive strength of the concretemember with fire retardant coating on the surface is far greater than that of theconcrete member without fire retardant coating after a high temperature fire.Some rules and knowledge are concluded about the fire resistance of the RCbeam and studies on the concrete with fire retardant coating on the surface at hightemperature at the same time, with the findings applied to the fire retardance design ofthe reinforced concrete structure.