Research On The Performance And Design Of External Thermal Insulation Sandwich Wall Panels In Severe Cold Areas

In severe cold areas,the winter is cold and long,and the freeze-thaw cycle is frequent,which puts forward higher requirements for the thermal insulation and durability of the steel structure outer wall panels.Traditional external retaining wall panels mostly use ordinary concrete(OPC),thermal insulation materials and metal connectors.They have the disadvantages of self-weight,poor durability and obvious cold bridges,which limit the development of prefabricated building envelopes.Therefore,it is of great significance to study the external lightweight sandwich wall panels suitable for severe cold areas.In this paper,expanded perlite-containing concrete(EPC),ultra-high performance concrete(UHPC)and fiber reinforced composite materials(FRP)are used as the inner and outer structural layers and connectors of the new external thermal insulation sandwich wall panel,through a combination of experiments and simulations.It studied the raw material properties of the new external thermal insulation sandwich wallboard and its optimized ratio,calculation and evaluation methods for frost resistance and thermal performance,as well as the overall optimization design method of the wallboard based on the comprehensive mechanical and thermal performance.Specific research The content is as follows:1.The influence characteristics and mechanism of aggregate-cement ratio,waterbinder ratio,admixtures,fiber types and their mixing,curing age,and preparation technology on the compressive strength and flexural strength of ultra-high performance concrete are studied.Based on deformation and earthquake,the strength and other indicators have determined the optimal ratio of ultra-high performance concrete,and parameters such as elastic modulus,apparent density and specific strength have been obtained;the water-binder ratio,the amount of expanded perlite and the impact of carbon fiber on the compressive strength of concrete containing expanded perlite have been studied.The influence law of strength,flexural strength and apparent density.The key mechanical performance parameters of the inner and outer structural layers of sandwich wall panels have been determined.2.Study the frost resistance of UHPC and OPC.Using the quick-freezing method,the concrete was subjected to 0,25,50,75,100,125,and 150 freeze-thaw cycle tests,and the freeze-thaw resistance of the concrete was evaluated by the mass loss rate and the strength loss rate.Studies have found that UHPC has excellent frost resistance.3.The thermal conductivity of UHPC and EPC is studied by steady-state method and transient hot-wire method,and the ratio of mechanical properties is further optimized and used as the structural layer material on both sides;different materials and different diameters are analyzed by COMSOL finite element,Different combinations of connectors,different materials and different numbers of purlins have been simulated for thermal performance,and the impact of connectors and purlins on the thermal performance of sandwich wall panels has been evaluated.4.The characteristics and mechanism of the influence of UHPC and OPC on the thickness and deformation of the wallboard are studied by COMSOL finite element;based on the deformation index,the position distribution of the connection node between the main structure and the wallboard is optimized;finally,combined with national standards and mechanical knowledge,Summarized and sorted out the design method of the external thermal insulation sandwich wall panel,and carried out the design and application in combination with engineering examples.