Mechanical Properties And Connection Study Of A New King Of CSIPs Structural Panels

SIPs(Structural Insulated Panels)have been widely used in building structures because of its light weight,high strength,good thermal insulation properties and excellent seismic performance characteristics.But SIPs have many defects,such as poor panel thickness stability,fireproof performance,corrosion resistance,prone to pests and buckling deformation.And the construction cost of SIPs increases with the cost of wood.Based on the SIPs,CSIPs(Composite Structural Insulated Panels)are established by using FRP with superior high strength to weight ratio,superior impact resistance and durability as face sheets.CSIPs overcome the disadvantages of SIPs,such as poor corrosion resistance,prone to pests and buckling deformation,and the strength of FRP is much higher than that of wood,so that the mechanical properties of CSIPs are greatly improved compared with SIPs.In this paper,the mechanistic properties of CSIPs are studied as follows.(1)According to the theory of large deflection thin plate and Reissner theory,the 4 order basic partial differential equation of the sandwich plate bending is established,and the analytical solution is obtained.In this paper,the bending and shear stiffness of CSIPs as the floor and roof under the linear load are derived,and the calculation formula of displacements and the stability critical load of CSIPs are determined;based on the Winkler elastic foundation model,the critical buckling load of CSIPs under local buckling is calculated,and the critical bonding stress is obtained.(2)Using the SOLID45 unit and SHELL181 unit of ansys14.0,the finite element analysis was performed on CSIPs respectively.Linear constitutive model is adopted to the material.The geometric nonlinearity and initial imperfection of large strain are considered in the stability analysis.The strength,stiffness and stability of CSIPs are analyzed which is based on the arc length method,and the results compare with the theoretical results.The influence of the thickness of the plate and the thickness of the core layer on the bending performance of CSIPs was analyzed.(3)Three testing pieces of CSIPs with length 1600 mm,breath 600 mm and thickness 108 mm are designed and fabricated,and static tests were completed.Ultimate load and failure modes of the structure are investigated by applying four points bending.Strain gauges are used to measure the strain of each measuring point at the same time displacement meters and dial gauges to measure deflections.The comparison of theoretical analysis results,finite element simulation results and test results gets mutual verification.(4)Proposing a king of the special-purpose twin-screw plate bolt for FRP member connecting,the semicircle of the screw is small,and its nut is large.It solves the problem of the fiber discontinuity and local stress concentration caused by the traditional bolt connection in FRP material.Through the finite element analysis of the traditional frictional high strength bolt and the new type twin-screw plate bolt with the same amount of steel,it is concluded that the new type bolt has high strength and bearing capacity.