Research On Basic Performance Of Prefabricated GRC Decorative Integrated Envelope Structure

In the recent years,GRC(Glass Fiber Reinforced Cement)has been widely used in building architectural epidermis because of its advantages of light weight,good designability and rich texture.Since the GRC curtain wall has an integrated function of decoration,insulation and enclosure,the GRC has an extensive application in actual engineering.With the development of the GRC materials as well as their application technique,some scholars have found the disadvantage of the traditional GRC is that the GRC board only bears external loads perpendicular to the panel,such as wind load,earthquake load,impacting load and so on.The integration and mechanical behaviors between the traditional GRC board and the attached steel frame were relatively poor.The main load-bearing system is the attached steel frame,so it is difficult to make full use of the high properties of the GRC.Therefore,the material utilization ratio was relatively low.To solve the above problem,this paper proposed a new type of connections called"Eight characters tendon"and a spacial envelope structure comprised of GRC materials and the attached steel frame.The advantages of the spacial envelope structure are that it can make full use of the different materials and that the constituent parts of the composite structure can work in good coordination.What’s more,it can significantly reduce the material consumption and cost.The main contents and conclusions are as follows:(1)Firstly,the GRC material,preparation and requirements of the design were studied.A mechanical model was established for the spacial envelope structure with GRC and attached steel frame.Taken the influence of wind load under consideration,the results show that the design of the spacial composite structure was feasible.The GRC materials and the attached steel frames show a good force-bearing performance and can meet the requirements of different working conditions.(2)Then,two different sizes of GRC board with sizes of 4.305m*2.015m and3.800m*1.015m were studied under the actual load simulation test.The deformation curve of the proposed spacial envelope structure fluctuated at the initial stage of loading,which was caused by the gap at the junction.When the spaces were eliminated,the load-displacement cure maintain a certain proportion.The bending stiffness of the parallel specimens was slightly different,and the value was smaller than 6.57%.The flexural rigidity of the proposed structure was closely related to the total thickness of the structure and the GRC panel,tectonic connection and the arrangement of the metal skeleton.The experimental results show that the proposed spacial composite envelope structure of GRC and attached steel frame has excellent mechanical behaviors.When these two types of materials were compounded,the utilization rate of material properties was significantly improved.A stable"integrated spacial envelope structure"can be designed and fabricated with integrated functions and effectively reduced material consumption.(3)At the same time,the thermal insulation and waterproof of the proposed structure were analyzed.The heat transfer coefficient of the composite envelope structure was studied,when the cold bridge ratios ranged from 15%to12%and to 10%.At the same cold bridge,the heat transfer coefficient shows an increase tendency with the decrease in the thickness of the insulation layer.With the same thickness of the insulation layer,the heat transfer coefficient increases with the increase in the proportion of cold bridge.Therefore,it is revealed that the thickness of the insulation layer and the proportion of cold bridge are the main factors that affect the heat transfer coefficient of the composite plate.It was necessary to consider the influence of the thickness of the insulation layer and the proportion of cold bridge in actual engineering.(4)Finally,the processes of prefabrication and installation as well as the application of the spacial enveloped structured were studied in actual engineering.Based on the advantage of the prefabricated envelope structure,some related standards and specifications were studied and given.Through the specific engineering application,it can be concluded that the prefabricated technique of the envelope structure can effectively improve the construction efficiency,structural stability,safety and reliability.At the same working condition,the proposed integrated envelope structure can significantly reduce the use of the materials.Compared with the conventional attached steel frames,the amount of metal was reduced from 20 kg/m~2~25kg/m~2 to about 15kg/m~2,and the reduction rate even amounts to 25%to 40%with a quite remarkable economic benefit.