Experimental Study On Fire-resistance Performance Of Steel Reactive Powder Concrete Columns With Different Section Sizes

With the development of national economy and science,the form of modern engineering structure is gradually developing to high-rise and long-span structure,Reactive Powder Concrete(RPC)began to come into people’s view.Composite structure of RPC and steel has super high compressive strength and good seismic performance.Its advantages are also reflected in strong anti-corrosion performance,can reduce the size of the component section,prolong the service life of the component,it in line with the development trend of urban architecture.On the other hand,due to the frequent occurrence of building fires,the losses caused by them are more and more serious,causing great losses and damage to the national economy and human environment.Steel Reinforced Reactive Powder Concrete structure(SRRPC)is more seriously damaged in fire because of its high steel content.However,there are few researches on fire resistance of Steel Reinforced Reactive Powder Concrete structure at home and abroad.In this thesis,five SRRPC columns with different section sizes are designed and fabricated.The influence of section size on the fire resistance of SRRPC columns is studied,the crack distribution,temperature field,axial displacement curve and fire resistance time of the specimens were analyzed.The fire resistance limit of SRRPC column was simulated by finite element analysis software ABAQUS.The conclusions are as follows.(1)RPC surface appears cyan-grey after high temperature.The section size of the specimens has no obvious influence on cracking degree and popping of the specimens.After high temperature,a great quantity of small cracks appear on the surface of the SRRPC column,most of which are vertical cracks.(2)During the process of heating up,the temperature curve trend of each measuring point is roughly the same.The temperature curve presents the "S" shape as a whole,which conforms to the characteristic that the closer the surface to which the specimen is exposed to fire,the faster the temperature increases.The larger the section size,the slower the temperature growth rate of the internal measuring point.(3)The displacement curves of each specimen have obvious characteristics:the displacement in the early stage is stable,and the displacement hardly increases;when the temperature reaches a certain degree,the displacement speed starts to accelerate and the displacement gradually increases until the fire resistance limit is reached.Some specimens undergo obvious brittle failure and the displacement rises in a straight line.(4)Section size is an important factor affecting the fire resistance limit time of SRRPC columns.The fire resistance limit time increases linearly with the increase of the cross-section size of the specimens.The relationship between fire resistance limit time and section size of SRRPC columns is obtained by data fitting,and the fitting effect is good.(5)The temperature and fire-resistance limit time obtained by numerical simulation are larger than the measured values,the error is within the allowable range,and the results agree well.