Research On Earthquake Resistant Capacity Of Large-span Steel Arches

Large-span spatial structure has its own characteristics in normal use. With relatively dense flow of people, if the large-span spatial structure cannot provide adequate earthquake resistant capacity, the earthquake damage to it will be much more serious than that to ordinary buildings. Regarding the inadequate earthquake prediction and evacuation, earthquake engi-neering has been the most effective and fundamental measure. This paper is based on a big project. It takes use of two kinds of finite element analysis software:ANSYS and SAP2000, using different methods of seismic analysis to analyze the earthquake resistant capacity of large-span steel arch structures.This paper first reviewed both domestic and international studies on earthquake resistant capacity of large-span steel arch structure. Then it did an overall and comprehensive summary of the current methods for earthquake resistant capacity analysis. Third, it presented several representative methods for earthquake resistant research in different stages. Based on the concept of reasonable arch axis, it provided for this project a reasonable arch axis. It also did numerical analysis on single-span steel arch and found the change patterns of the steel arches under different slenderness ratio, span ratio and the initial defects. Based on finite element theory, it carried out modal analysis on the overall structure and proved that its frequency dis-tribution was even and proper, without apparent jumps. The fundamental frequency value of the overall structure is low, indicating that the overall structure was softer than it should be. This fact was considered in the design to strengthen the lateral support of the structure. The earthquake response analysis was conducted to test the project, specifically using the vibra-tion disassembling response spectrum method and the time-history analysis. In the method of vibration disassembling response spectrum, it focused on the combinations of the vibrations (SRSS method and the CQC method) and made a preliminary judge. This paper further stud-ied and discussed the role of vertical earthquake and its influence towards horizontal earth-quake. In time-history analysis, this paper focused on the selection of earthquake wave. It first revised the acceleration effective peak and effective time of the three selected earthquake waves. Then, it studied the seismic capacity of the structures under the situation of many earthquakes and concluded with the distribution pattern of the internal force of the overall structure. It compared the results from the vibration disassembling response spectrum method and the time-history analysis and drew some useful conclusions. Finally, this paper proposed some suggestions on the earthquake resistant design of such structures.