Analysis On The Dynamic Stability Of Beam String Structures Under Earthquake Action

Beam String Structure (BSS) is composed of upper structural member, lower string and struts, which is a new type of long-span hybrid structure. This type of structure has been applied in many domestic and abroad projects, and the research on its theories and experiments has been gradually developed. However, in contrast with other spatial structures, there is still certain extent blank in the field of dynamics of BSS, especially its dynamic stability. Therefore, the research on dynamic stability of BSS is one of the most important problems in the field of spatial structures.In this paper, the classifications and characteristics of BSS are summarized, and the domestic and abroad developments for BSS are reviewed. Based on characteristics of BSS and the limits of the existing dynamic stability criteria, a practical judgment method of dynamic stability of BSS is presented. According to the nonlinear finite element theory, the basic principle of the finite element method about geometrical nonlinearity and material nonlinearity is analyzed. The analysis and the calculational method of the nonlinear finite element of BSS are established.Due to the strong nonlinear earthquake response of BSS, the nonlinear finite element analysis and time history method are adopted. First, the structure of solid cable-truss of the Guangzhou International Convention and Exhibition Center is analyzed. By static analysis, modal analysis, and dynamic response analysis, the dynamic stability is further analyzed, and response rule of this type of BSS under earthquake action is presented, and the critical load of dynamic stability was obtained.Subsequently, the dynamic stability of the BSS is analyzed under earthquake action, including the effects of the number of struts, height-span ratio, sag-span ratio, prestress of string, restraint type of supports and the span of the structure. The results are compared with that of static stability. Some suggestions are put forward to choose the proper structural style in project design.