Study On Bending Performance Of Precast Ultra-high Performance Concrete Sandwich Panels

Prefabricated sandwich insulation wallboard has the characteristics of fast construction speed and good insulation effect,especially it can realize the same life of insulation materials and structure,which makes prefabricated sandwich insulation wallboard gradually become the form of building external wall.Ultra high performance concrete（UHPC）is a new type of cement-based composite material,which has the characteristics of ultra-high compressive strength,tensile strength,high toughness and high durability.When it is applied to the sandwich insulation wallboard structure,it can improve the structural bearing capacity,reduce the weight of the building,and then improve the overall seismic capacity of the building.However,there is a lack of design code for UHPC structure in China,which limits its application in sandwich insulation wallboard.Therefore,based on the 2019 Science and Technology Project Plan（2019-K-085）by the Ministry of Housing and Urban Construction and Anhui Provincial Natural Fund Project（1908085ME144）,this paper carried out the bending model finite element parameter analysis of UHPC sandwich insulation wallboard,and studied its mechanical performance,failure mode,cracking and ultimate load,which provided a reference for the specification of UHPC sandwich insulation wallboard.The main contents and conclusions are as followsThrough the finite element study on the bending performance of UHPC sandwich insulation wall panel,the results show that the bending failure mode of UHPC sandwich insulation wall panel is similar to that of ordinary concrete sandwich insulation wall panel,and UHPC sandwich insulation wall panel has also experienced three different stress stages:elastic stage,crack development stage and failure stage.The cracking,ultimate load and structural stiffness of UHPC sandwich insulation wallboard are greater than those of ordinary concrete sandwich insulation wallboard.The cracking load of UHPC sandwich insulation wallboard is significantly greater than the ultimate load.UHPC sandwich insulation wallboard shows excellent bending performance.Through the analysis of the influencing factors of bending performance of UHPC sandwich insulation wallboard,it shows that when the number of internal connectors is small,changing the number and arrangement of connectors has a great influence on the mechanical performance and ultimate load of the wallboard;when the number of internal connectors reaches a certain number,increasing the number of internal connectors has a great influence on the bending performance,cracking and ultimate load of the wallboard The lifting of the load is no longer obvious;the use of the same specification of GFRP connector to replace the steel bar connection,the wall board’s ultimate deflection growth is obvious,increasing the number and diameter of the GFRP connector has obvious effect on reducing the deflection of the wall panel;improving the thickness of the wallboard can significantly improve the bending performance,cracking and ultimate bearing capacity of the wallboard;use foam concrete instead of EPS material.When the material is used as the internal insulation material of the sandwich wall panel,the ultimate load of the wall panel increases slightly,and the cracking load of the wall panel changes little.According to the research on the load transfer behavior and failure mode of UHPC sandwich insulation wallboard structure model,a reasonable wallboard calculation model is determined.Through the analysis of the finite element parameters of UHPC wallboard,a relatively simple and accurate calculation formula of cracking moment and bending capacity of UHPC and ordinary concrete sandwich insulation wallboard is derived,which can be used as a reference for engineering practice.Figure [30] table [20] reference [42]...