Response analysis of cable net structure supporting reflector of FAST under seismic multi-support excitations.

Seismic ground motions are spatially varying when reaching the site of structures after long distance transmission. It is more realistic to consider the coherency effects by multi-support excitations than uniform excitations. The supporting structure of the five-hundred-meter aperture spherical telescope (FAST) is a new kind of cable net structure, thus it is necessary to investigate the seismic responses considering the spatial variations under multi-support excitations. Based on available excellent model of seismic ground motion, was used to simulate the seismic ground motions of 338 points within the area covered by FAST. The seismic ground motions at the 2 395 beamings of FAST were obtained via linear interpolation between the 338 points. The time-history responses of supporting structure of FAST under multiple-support excitations and uniform excitations were analyzed with ANSYS. The results show that the seismic coherency effects poses different influence on the supporting structure of FAST in three component directions. It is thus necessary to consider the seismic coherency of all three component directions in the analysis. Affected by the seismic coherency effect under three-dimensional seismic excitations, the stress in 94.08% of the main cables is increased by an average of 87.04%, the stress in 43.51% of the tie-down cables is increased by an average of 21.88%. Under three-dimensional multiple-support seismic excitations and three-dimensional uniform excitations, the maximum tensile stresses of the cable are 835.43 MPa and 671. 10 MPa, respectively, and both are smaller than the characteristic tensile strength of the cables of FAST. The supporting structure of FAST can withstand the expected seismic ground motions. [ABSTRACT FROM AUTHOR]