Research On Fire Resistance Of Laminated Plates

The composite slab has been widely used in reinforcement engineering and new construction.Increase the thickness of the floor is to enhance the floor carrying capacity of the most direct and effective way;in the existing building renovation and reinforcement,often in this way the original old concrete floor board rough treatment,and then pour a layer of new concrete To achieve the reinforcement of the original floor,which will form a second pouring forming the overall work of the composite slab.The composite slab member is not only applied in the reinforcement engineering,but also has been widely used in the assembly of the whole structure,and has achieved good economic benefits.At present,the study of mechanical properties at room temperature has made a lot of research results,but the study of the fire resistance of the composite slab is very limited.The main results of this paper are as follows:(1)The plate-type concrete simply supported laminated strip under the action of fire,the failure mode of the specimen is cross-bending failure and bearing shear failure,indicating that the high temperature effect significantly reduced the tensile strength of the specimen,Bearing capacity.(2)The height of the stacking surface and the treatment of the stacking surface have no obvious effect on the temperature field distribution in the plate.When the specimen is about 30 min fire,the temperature difference between the plate and the bottom plate is 50 mm Large temperature stress,bearing,overlapping surface and mid-span cracks began to carry out.(3)The burning time is short,the specimen temperature is not very high,laminated cross deformation similar to cast-in-place slab,prefabricated and laminated layers that can work together;with increasing the combustion time of growth,the furnace temperature,the composite surface smooth laminate,laminated surface integrity first tends to failure;laminated surface is roughened or arrangement of reinforcing laminate,when the prefabricated thickness,pouring composite layer thickness is relatively small,with the fire behavior of cast-in-place slab,laminated surface still has the overall ability to work.The remaining laminates,which have been roughened or arranged with reinforcement,will eventually collapse in the event of fire.(4)The slab with the whole pouring slab and the laminated face have no failure,and under the action of fire,the vertical crack is produced in the middle of the plate,and the shear inclined cracks are produced at the abutment,and the cracks are developed from the bottom of the slab.Under the action of high temperature lamination failure of the laminate,will produce a redistribution of internal force,the force mechanism of plate change,precast slab and post pouring laminated layer assume their respective loads,two flexural members similar to stacked together.Under the combined action of temperature,stress and load,the vertical cracks on the middle span of the plate overlap and develop upward,and the vertical cracks are formed on the prefabricated layer.Inclined cracks are produced on the precast and laminated layers at the support.(5)The same lamination height laminate,laminated surface is roughened the laminate deflection in fire deformation minimum layout inserted reinforcement of the largest leveling treatment,it is showed that the composite surface smooth laminated in the fire when the stiffness decrease of prefabricated layer and stack performance laminated work is the worst.(6)The same stacking surface treatment,the thickness of the pouring plate and the thickness of the prefabricated plate thickness d ? 1 when the component fire resistance is the worst;d ? 1 when the fire resistance is better and d <1 component fire resistance is better than d> 1 components.(7)the smooth surface of the 1 #,4 # plate to meet the deformation limit and touch bearing capacity failure criteria,fire resistance were 195.5min and 212 min.It is easier to describe that the laminated surface of the laminated surface is more likely to be damaged due to insufficient bearing capacity in the event of a fire.The main results of this paper are as follows:(1)After pouring,prefabricated thickness ratio of 0,44)and the overlapping surface of the plate through the rough treatment of the destruction of the form of bending;other forms(1)after the break Of the laminated plate due to bearing damage or disengagement surface failure and failure.(2)Residual bearing capacity of the specimen after the fire test: the residual bearing capacity of the composite plate with the thickness of the prefabricated plate close to the thickness of the prefabricated plate is about 50%;the overlapping surface is roughened or arranged and the cast,The residual capacity of the composite plate with large difference of plate thickness is about 80%,and the residual load resistance of the pouring plate is about 80%.(3)the rigidity of the specimen after the fire test: the reduction of the stiffness of the pouring plate is small;the stacking surface height is 90mm(after pouring,the prefabricated thickness ratio is 0,44)and the overlapping surface is roughened 8 # The stiffness of the laminated plate with the height of 50mm(the upper and lower plate thickness ratio is 1.6)is the same as that of the whole pouring plate.The other forms of the joint are more serious than the slab.