Study On Steel-concrete-steel Structures In Nuclear Engineering Subjected To A Large Commercial Aircraft Impact

Steel-concrete-steel(SCS)structure is a kind of composite structure formed by cladding steel plates on concrete,which has good mechanical properties and impact resistance.SCS structure has been applied in the shield building of the third generation nuclear power unit in China.Since 2009,a design specific assessment of the impact of a large commercial aircraft on a new power plant has been considered in some countries such as the United States,France,and China,but the research in this field in our country is not mature.A study on SCS structure against a large commercial aircraft impact is carried out in this dissertation.The main work and research results are as follows:(1)Based on the plastic hinge analysis of large deformation dynamic progressive buckling of the shell,a discretization criterion of finite element for the elasto-plastic analysis of large deformation suitable for aircraft impact conditions is proposed,which can be used to guide the mesh size division of finite element of a large aircraft,so as to ensure the simulation accuracy of finite element model and reduce the calculation cost.The dynamic constitutive model and parameter setting of aircraft,shield building and auxiliary building materials in the impact numerical simulation are determined by comparing with the components impact tests of aluminum alloy,steel and concrete.(2)The refined nonlinear finite element models of a large commercial aircraft and a nuclear power plant are developed,which have been used for impact research of large commercial aircraft and safety evaluation of nuclear power plant.Not only external structures including aircraft fuselage,wing,engine,empennage,skin,but also distribution changes of aircraft mass and stiffness and internal structures including fuselage frames and strings,fuselage floor,wing and empennage ribs are considered in the finite element model of aircraft;details of the weak parts of the shield building,such as air intake,conical roof and annular water tank,are fully considered in the model of nuclear power plant.(3)The damage characteristics of the shield building subjected to the large commercial aircraft are comprehensively evaluated by coupling method,and local damage forms in the impact area and vibration response laws away from the impact area are obtained.The effects of impact velocity,impact angle,aircraft mass,diameter of tie bar,outer steel plate thickness,concrete strength and water in annular water tank on the displacement of the impact area are compared and analyzed,the differences of the structural response of the shield building are studied under the condition of presence or absence of the auxiliary building and damping,and the damage characteristics of the shield buiding subjected to engine alone are analyzed.(4)The decoupling analysis methods used in the current nuclear engineering design and recommended in the relevant codes for the calculation of the large aircraft impact problems are studied,and the limitations of the current design calculation method are analyzed.Through the impact force analysis by the Riera model,aircraft impacting the rigid wall and aircraft impacting the shield builing,the impact force time history and distribution laws of aircraft fuselage,wing and engine at different impact speeds are obtained.A reasonable decoupling evaluation method of the large aircraft impact problem with universality is presented,which makes the decoupling method suitable for the analysis of local damage of large aircraft impact.(5)A formula for calculating the perforation resistance of SCS panel with tie bar based on energy analysis is presented.By a comparative analysis of 51 working conditions,including different tie bar,different steel plate and concrete,different projectile,the formula can effectively evaluate the perforation failure of SCS panel,and it can be applied in the relevant design and safety assessment.