Research On The Positive Mechanical Properties And Design Method Of Laminated Glass With Cold Bending Distortion

The curved glass curtain wall has been widely used because of its unique artistic effect.The glass cold forming using the elastic deformation of the glass will be pressed into a curved surface glass,the duration and cost of glass curtain wall project is greatly reduced,and has a good visual effect.However,there are few researches about the cold bending glass at home and abroad,which can’t meet the needs of the actual engineering.Therefore,it is urgent to solve the problem of the design theory of the cold bending glass,whether it is the evaluation of the construction project or the application of the project in the future.Nine laminated glass specimens were designed,and the single corner forward bending test was carried out,the stress of the glass panel was found to increase linearly with the twist rate.In the process of cold bending,the upper surface of the two adjacent corner points of the cold bending point and the lower surface of the cold bending point have high stress.The maximum stress is located at the upper surface of the adjacent corner points in the short side direction of the cold bending point.The thicker the glass panel,the greater the stress generated by the cold bending process.The load tests were made for the specimens after cold forming.The results show that the stress and deflection of the glass panel are increased with the increasing of the load,and the trend is nonlinear.The maximum stress of the plate glass is located at the center of the lower surface of the glass panel.While the maximum stress position changes with the increase of the load,because of the influence of the residual stress in the cold bending glass.When the load is small,the maximum stress is located at the upper surface of the adjacent corner points in the short side direction of the cold bending point.When the load is larger,the stress value of the central zone of the lower glass panel is maximum.Due to the glass panel is always in the state of simply supported edges in the process of loading,so the deflection value of the middle point of each test piece is small,and the maximum deflection value is located in the center of the glass panel.According to the range analysis and variance analysis of stress and deflection in the process of loading,twist rate of cold bending and thickness of glass panel have significant in:fluence on the stress and deflection of the glass panel,stress and deflection increases with the bending distortion rate increases,decreases with the increase of the thickness of the glass panel,while the PVB film thickness has no significant effect.Using ABAQUS finite element software to simulate the cold bending process and the loading process of laminated glass,the accuracy of the model has verified by comparing with the experimental results.The cold bending process is analyzed and found that the influence of the factors on the maximum stress is the same as that of the load test.Based on the calculation formula of "Technical code for glass curtain wall engineering"(JGJ102-2003),considering the stress characteristics and influencing factors of cold bending glass,the cold bending stress coefficient λσand the cold bending deflection coefficient λd are introduced.The calculation formula of the cold bending coefficient is established,the suggested formula for the maximum stress and the maximum deflection of cold bending laminated glass under wind load are obtained.