| The paper designed one light steel keel concrete composite external wall panel.In order to study the thermal performance and fire resistance of the composite wallboard,the paper conducted the thermal performance test and analyzed the effects of the thickness of rock wool,the height of the keel web,the distance of the keel and the thermal conductivity of the material on the thermal insulation and the fire resistance of the composite wallboard.The specific research contents are as follows:(1)Thermal performance test and ABAQUS finite element analysis of composite wallboardThe paper designed 3 groups wall panels with different thickness of rock wool,introduced the fabrication and installation process of the specimen and the test process of the protective hot box in detail.The temperature distribution of the inner and outer walls of the wall was measured to find the heat bridge effect of the keel,and the heat transfer coefficient of the wall was obtained through the heat balance in the heat box,so as to compare the influence of the thickness of the rock wool filling and other factors on the wall thermal insulation.The results showed that: the temperature field of the wall plate was greatly influenced by the heat bridge,and the effect of the heat bridge of the keel was remarkable;the influence of the earth keel heat bridge was not negligible;with the increase of the thickness of the material rock wool,the heat transfer coefficient of the wall was reduced obviously,the heat preservation effect was improved obviously,but increase to a certain thickness and effect was not obvious,in which the 60 mm thick rock wool was not satisfied with the standard,and the thickness of 80 mm and the thickness of 100 mm were satisfied.Based on the experimental data of 3 wall panels,the correctness of two-dimensional heat transfer model of composite wallboard was verified by ABAQUS finite element.On this premise,the parameter analysis was carried out through finite element : when the height of the web was small,the wall heat transfer coefficient can be reduced effectively by increasing the height of the wall,but when the height of the web was further increased,the decrease of the heat transfer coefficient was no longer obvious;the increase of the distance of the keel resulted in a linear decrease of the wall plate heat transfer coefficient and improvement in the heat preservation performance of the body.When the distance of the keel was large to a certain degree,the reduction of the heat transfer coefficient began to decrease;and the thermal performance of the composite wall panel with plasterboard as the inner sealing plate has no significant difference compared with the cement board.(2)Fire resistance performance test and ABAQUS finite element analysis of composite wallboardThe paper designed 7 groups of wall panels with different filling materials and inner sealing materials.The purpose of this study was to investigate the influence of rock wool filled thickness on fire resistance of composite wallboard through horizontal furnace test.The results showed that: the stability of W1,W2 and W3 specimens were lost under fire.The result were not satisfied with the current fireproof limit requirements of the multi-storey civil building combination wall board in our country;the stuffed insulating material rock wool has good insulation and fireproof ability,the fire resistance of W2 specimen filled 80 mm thick rock wool was 7min higher than that of W1,and the W3 specimen filled 100 mm thick rock wool was 12 min higher than W1.The influence of foam concrete as thermal insulation material and gypsum board as inner sealing plate was studied through vertical furnace test.The results showed that: The fire resistance of the W4~W7 specimens reached the standard 60 min.Compared the W4 with the W5,the increase of the thickness of the foam concrete can improve the fire-resistant performance of the wall panels.The integrity of the specimens was obviously better than the W6 and W7 specimens filled with rock wool.The cracks on the surface of the back fire surface were open and the vertical keel were not flexed,the adiabatic was better.Comparing the temperature and fire time of W1~W3 and W6~W7,it was found that the fire resistance of the wall panels made of gypsum board was better.The correctness of two-dimensional heat transfer model of composite wallboard was verified by ABAQUS finite element.On this premise,the parameter analysis was carried out through finite element: the refractory limit of the wall panel was not obviously improved by adjusting the height of the web plate;when the distance of the keel was 400mm-600 mm,the temperature of the back fire surface would be linearly reduced during the 1h fire disaster simulation.When the spacing was 500mm-600 mm,the insulation of wall panels would be greatly improved.The wall plate of plasterboard,the thickness of plasterboard from 10 mm to 20 mm made the temperature of the back fire surface reduced by 32℃,the thickness of plasterboard from 20 mm to 30 mm made the temperature of the back fire surface lowered 6.9℃.It was proved that increasing the thickness of the plasterboard inner sealing plate can obviously improve the fire resistance of the wall plate.When the thickness of the plasterboard was thinner,the thickness of the plasterboard can increase the fire resistance of the wallboard especially,and the temperature of the back fire face was not more than 180℃,which met the standard requirement of the 1h fire resistance limit.It was proved that the fire-resistant concrete filling thickness increased the fire-resistant performance of the wall panel.And the temperature of the back fire surface did not exceed 180℃,meeting the requirement.(3)Optimal designOn the premise of verifying the correctness of the ABAQUS finite element model,the optimization suggestions are as follows: foam concrete substitutes for rock wool as a new filling material;the height of the keel web is 120mm~140mm;400mm or 600 mm is taken in the general engineering application to ensure the reliability and safety of the wall plate connection;the gypsum board substitutes for the cement board as the inner sealing material;recommend to use metal connectors to weaken the influence of thermal bridge in wall panels and improve the thermal performance and fire resistance of composite wallboards in the controllable range of production cost. |
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