Stability And Progressive Collapse Analysis Of Long-Span String-Supported Single-Layer Reticulated Shell

The reticulated shell structure is widely constructed in the field of civil engineering for its characteristics of long span,beautiful appearance and low cost of steel.The reticulated shell generally occur buckling fail in case of extreme conditions.So civil engineers pay much attention to the stability to the design of reticulated shell structure.Due to the low redundancy of the reticulated structure,the fail of some key components may cause the remaining structure collapse continuously.The string-supported single-layer reticulated shell structure(SSRS)is a new type of reticulated shell structure,which is composed of single-layer reticulated shell,stretching cable and supporting bar.So far,the research on the stability and progressive collapse of the SSRS are relatively rare.It is necessary to study the stability and progressive collapse.Base on a long-span shell canopy project,the research on stability and progressive collapse characteristics of the SSRS structure is conducted.The FE(finite element)model of the SSRS is established by ANSYS and LS-DYNA program and its static stability,dynamic stability and continuous collapse resistance are analyzed.The main research contents include:(1)Static stability analysis of the structure.The analysis includes linear buckling and nonlinear full process analysis.The theoretical critical load of the structural is obtained by linear buckling analysis.Based on the ultimate buckling and branch buckling theory,the nonlinear full-process analysis is conducted.The influences of material nonlinearity,initial imperfections,and uneven load distribution on the stability ultimate strength are put forward.(2)Dynamic stability analysis of the structure.The analysis includes modal analysis and time history analysis.Structural vibration characteristics were obtained by modal analysis.Based on the B-R criterion,the time history analysis of the structural dynamic stability under EL-Centro wave,Taft wave and Tianjin wave are carried out considering initial defects and uneven load distribution.(3)Performing a continuous collapse analysis on the structure.The analysis determines the key members of cable,support bar and net shell rod by removing the component method.The axial force change and collapse process of the remaining structural members are analyzed by applying static and ultimate loads to the remaining structure after removing the key element.The analysis results show that the material nonlinearity has great influence on the static stability bearing capacity of the structure while the initial defect has little.Under the condition that the load is unevenly distributed along the short span of the structure,the critical load capacity decreases gradually with the live-dead load ratio increases.The structure is destroyed when the seismic acceleration amplitude is up to 700 gal under the action of EL-Centro wave.The joint of the hybrid structure between the single-layer shell and string-supported single shell is the weakest.