Study On The Protective Performance Of Aluminium Honeycomb Sandwich Layer Coating On Reinforced Concrete Wall Under Low-speed Impact

Reinforced concrete structures may be subjected to large-mass,low-speed,and highenergy(accidental impact)loads during regular service,and more systematic research is needed on the dynamic response,damage assessment,and reasonable and adequate impact protection of key,reinforced concrete walls(such as essential shear walls of highrise buildings in earthquake areas and mountainous areas,and critical protective structures of important structures)with high requirements for impact load under lowspeed impact load.The porous sandwich structure with the classic hexagonal aluminum honeycomb as the core layer has the characteristics of low relative density and good energy absorption effect.It is widely used in various industrial fields such as ships,vehicles,and aerospace and plays a good role in energy absorption and impact resistance.Based on the principle of energy absorption,this dissertation proposes a method of introducing honeycomb aluminum sandwich structure into reinforced concrete walls for impact protection;Theoretical analysis,finite element and pendulum test research are carried out with the core of the impact protection effect of key reinforced concrete walls under low velocity impact,damage assessment and honeycomb aluminum sandwich layer on reinforced concrete walls,providing theoretical support and design reference for the impact protection application of honeycomb aluminum sandwich layer.The dynamic research on concrete,aluminum honeycomb and sandwich structure is carried out from the material level.Through the split Hopkinson compression bar test of concrete,aluminum honeycomb and sandwich structure,the isolation effect of aluminum honeycomb and sandwich structure under shock wave is preliminarily verified.Given the significant difference between honeycomb material wall thickness,honeycomb hole side length and engineering structure,a numerical simulation method for calculating the equivalent material properties of aluminum honeycomb by using the representative volume element and periodic boundary conditions of micromechanics is proposed,and the equivalent elastic properties of aluminum honeycomb are studied.Based on the characteristics of accident-type impact,the large-scale pendulum impact tests of ordinary reinforced concrete walls and aluminum honeycomb-covered reinforced concrete walls are designed.Based on the pendulum test of the ordinary reinforced concrete wall,the finite element model is established,and the results of the pendulum test and finite element calculation are checked and verified.The damage,dynamic behaviour and parameter influence of impact load on the reinforced concrete wall are studied in detail and systematically.The significant cracks of reinforced concrete walls are quantified using MATLAB to realise image processing.According to the numerical simulation,the concrete damage ratio is put forward,and the concrete damage statistics are realized using PYTHON language parametric post-processing method to quantify the overall damage degree of reinforced concrete members.The dynamic load checking method of reinforced concrete members in the design stage is proposed based on experimental research and finite element calculation.Based on the pendulum tests of reinforced concrete walls with different aluminum honeycomb protective covers,the protection effect of aluminum honeycomb cover on reinforced concrete walls is analyzed.It has been proved that the energy consumption characteristics of aluminum honeycomb cover are related to the protective effect of reinforced concrete walls under impact load,and the energy absorption effect and protection effect of aluminum honeycomb cover is related to the parameters of aluminum honeycomb cover.The aluminum honeycomb cover can effectively reduce the overall effect of impact on the reinforced concrete wall,eliminate the local deformation and local damage to the wall,effectively reduce the length and width of concrete cracks,improve the airtightness of reinforced concrete,and effectively improve the impact resistance of the overall composite structure.Moreover,the reasonable selection of aluminum honeycomb parameters can also eliminate the rebound and secondary impact of impact load and secondary damage.The theoretical impact model of aluminum honeycomb cladding of reinforced concrete wall is built,and the impact model under square flat head impact is proposed and deduced.The impact energy consumption theory of the covering layer considering delivery loss is proposed from aluminium honeycomb materials’ energy absorption.Based on the impact energy and energy absorption characteristics,the calculation of aluminum honeycomb consumption and the estimation and verification of honeycomb crushing depth is realized.Based on the pendulum test of reinforced concrete wall with aluminum honeycomb cover,a finite element model is established to check and verify each other,and the parameters of aluminum honeycomb cover are analyzed.From the protective effect of different aluminum honeycomb covers on reinforced concrete walls,the design and optimization principles of aluminum honeycomb cover are determined to guide the design and parameter optimization of reinforced concrete structures when aluminum honeycomb cover is introduced in the design and reinforcement stage.By experimental,numerical and analytical investigation on the introduction of aluminum honeycomb covered reinforced concrete walls,the aluminum honeycomb cover is designed and verified numerically for the previous reinforced concrete slabs,and the feasibility of the aluminum honeycomb cover design method is verified.The protective effect of aluminum honeycomb covers and other standard anti-impact protection measures are compared.