| This article is intended for the effectiveness of the reinforced concrete beam after using Steel mesh composite mortar reinforced by the fire.Our study were combined using the computer simulation analysis,the fire test specimens and low cycle reciprocating load test.As the same time,the method reinforced concrete frame beam as the object to study the performance after reinforcement,such as the fire performance and influencing factors of temperature field,the factors influencing fire damage and seismic performance.And obtained the following results:(1)The test of fire performance: Using the test of fire,two RC frame beams had tested under fire during 90 min and 120 min,respectively.The experiment measured the temperature of the specimen interior point,the deflection of the beam end,the destroying depth of concrete by the chisel,the compressive strength of concrete after fire and the the strength of the reinforcement after fire,etc..The test results show that the bearing capacity of the reinforced concrete frame beam is reduced more when it was 90 min or 120 min after fire.The reinforcement mechanics performance is reduce not very obvious.The main damaging is concentrated in concrete.No matter what the bearing capacity of structure or mechanical properties of material are both falling,but the specimen of 120 min after fire falling less than the 90 min.(2)The influencing factors of temperature field: Using numerical simulation software of ABAQUS to simulate the fire test,and compared with the test results to ensure the correctness of the model.Then the work is established some model to analysis the multiple factor of affected the temperature field,such as the plane number of suffered fire,the thickness of protective layer,the section size and so on.Through the analysis found that the reinforced concrete internal warming faster with the surface number of suffered fire increased.Especially temperature has a obvious rise when its suffered fire changed a double-sided from the single side.So when its increasing thickness of protective layer appropriate,it can help reinforced concrete structures to increase the fire resistance.The fire resistance performance has a obvious increase with the length of a rectangular structure section size increase within 300 mm,essentially unchanged over 300 mm.(3)Determination the damaged depth after suffered fire: According to the depth of remover after suffered fire test and the temperature field simulated by ABAQUS.It can determine the highest temperature reached 400? in the surface and the damage of reinforced concrete is assumed critical temperature.In this work,it has set up a variety of section size and models by suffered fire time.Finding out the critical depth of temperature in cross section,draw form of the relationship about damage depth,section size and the time suffered fire.It indicate that the depth of removed after suffered fire has a obvious reduce when the length of a rectangular structure section size increased within 300 mm.It has a little impact when it over 300 mm.(4)The study of seismic performance: Two RC frame beams after fire strengthened with ferrocement and one RC frame beam without damaging by fire have been tested under cyclic loading.The strengthening effect of ferrocement is checked and analyzed.Seismic bearing capacity,ductility,failure modes and hysteresis characteristic of all beams are tested.The results show that: The top deflection of the beam after fire is easy to crack down,we can analysis the experiment phenomenon from the ductility of the structure,structure stiffness,the structure of energy consumption and so on.These effect of aspects of structural ductility,stiffness,energy dissipation is good before the specimens strengthened with ferrocement mortar reaching the ultimate bearing capacity.Even it is better compared to mechanical properties of the specimens.But its structure begin to destruct and a variety of mechanical indicators are falling faster than contrast specimen after reaching the ultimate bearing capacity. |
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