Study On Fire Resistance Of Double-Steel-Plate Concrete Composite Wall

With the advantages of high bearing capacity,high lateral stiffness and good seismic performance,the double-steel-plate concrete composite wall is increasingly used in high-rise buildings.As a lateral force resisting component,the double-steel-plate concrete composite wall should bear and transmit vertical load in the process of daily use.At present,researches on the mechanical properties of double-steel-plate concrete composite wall at room temperature has achieved fruitful results,but the research of mechanical properties under fire is still rare,so it is of great theoretical and engineering significance to study fire resistance of double-steel-plate concrete composite wall under the combined action of fire and axial pressure.In addition,the influence of fire protection measures is not considered in existing studies on fire resistance of double-steel-plate concrete composite wall.Therefore,in this paper,the fire resistance of double-steel-plate concrete composite wall is studied by experiments,numerical simulation and theoretical analysis.The specific works are as follows:(1)Study on fire resistance of double-steel-plate concrete composite wall.The distribution characteristics of temperature field,fire resistance time and deformation form of composite wall are studied through experiments,which is under the action of fire and axial pressure.On the basis of the experiment,with selecting the reasonable mechanical and thermal properties of the materials,considering heat convection,radiation and conduction,the numerical model of fire resistance of the wall is established by using the finite element analysis software ABAQUS.And parametric analysis is carried out on the factors that may affect temperature field distribution of composite wall section(such as fire time and section steel ratio)and axial displacement of member(including spacing between studs and split bolts,height-thickness ratio and axial compression ratio).Parametric analysis shows that:with the increase of fire time,the temperature gradient becomes smaller and smaller,and the temperature difference value between middle part of concrete and steel plate of fire surface is more than 67% from 30 min to 180 min;increasing the distance between studs and split bolts will increase axial expansion deformation and axial compression deformation of the wall at the beginning of the fire;when the height-thickness ratio is greater than 16,the change of the height-thickness ratio has no obvious effect on the axial expansion displacement value under 180min;increasing the axial compression ratio will reduce the axial expansion displacement of the wall at the initial stage of fire,and the axial compression deformation will be increased under the same temperature.(2)Study on fire resistance of double-steel-plate concrete composite wall.According to the defects of existing fire protection measures for steel structures,this paper puts forward a composite fire protection measure which combines 50 mm rock wool board and 3mm expansive fire-retardant coating;in addition,this paper studies the influence of common fire protection measures(such as 50 mm autoclaved lightweight concrete plate and 30 mm non-expansive fire-retardant coating)and composite fire protection measure on the fire resistance of double-steel-plate concrete composite wall through experiments.Moreover,the fire resistance time of 3 groups of composite walls can meet the requirements of the 3 hours fire resistance of the first level load-bearing wall members.Composite fire protection measure can effectively restrain local buckling of steel plate on fire surface;the parametric analysis of the common fire protection measures shows that,using 20 mm ALC board or 10 mm non-expansive fire-retardant coating to protect the composite wall,the temperature of structures do not reach the critical temperature.At the same time,combined with the test phenomena of 3 groups of tests,this paper gives reasonable suggestions for the fire protection measures of double-steel-plate concrete composite wall in projects.