STUDY ON STATIC AND DYNAMIC BEHAVIORS OF TRUSS STRING STRUCTURE WITH DOUBLE CABLES

摘要

The cable relaxation plays a key role in the failure of truss string structure (TSS), which has been a problem of prestressed span string structures. In order to relieve the cable relaxation, a new type of truss string structure with double cables (TSSDC) was introduced in this paper. And the static and dynamic behaviors of TSSDC were determined using numerical simulations, by which the changes of internal forces in both truss and cables under static and dynamic conditions were investigated. The computational models of TSSDC and TSS were established by finite element method and the time history records of cable force were obtained. The effects of unique structural parameters on dynamic characteristics of TSSDC were discussed. The results show that the static behavior of TSSDC is similar to TSS with the increasing of live load. The dynamic performance of TSSDC is improved significantly due to the reduction of cable relaxation. Intensive state non-linearity appears just before structural failure of TSS. Due to the application of double cables, the degree and occurrence number of cable relaxation and state nonlinear condition decrease markedly, which leads to the increase in the margins of structural safety and the relief of cable relaxation. And the value range of structural parameters (e. g. sag-span ratio, length ratio of horizontal strut and inclination degree of slant strut) influence the seismic performance of TSSDC significantly and is optimized.