ANALYSIS OF THE PRETENSION LOSS OF SUSPENDOMES SUBJECTED TO STRONG EARTHQUAKES

Six suspendome models with different pretensions，rise-span ratios，bearing connections，symmetries and rigidity of substructures were employed to investigate the pretension changes in cable-strut system as well as the residual deformations of the upper reticulated shell of this kind of structure subjected to strong earthquakes． It was discussed the difference of structural pretension losses corresponding to four different checking criteria for the members of upper reticulated shell，i． e． elastic design under 7 degree frequently occurred earthquake，elastic design under 8 degree frequently occurred earthquake，unyielding design under 8 degree fortification intensity earthquake and elastic design under 8 degree fortification intensity earthquake，for each model respectively subjected to fortification intensity and rear earthquakes． The results revealed that there generally exists pretension loss in the cable-strut system of suspendome after the action of a strong earthquake，especially in the inner ring cables． The changes of cable's internal forces are much more sensitive to the symmetry of substructure，the form of bearing connection and the rise-span ratio of upper reticulated shell． In case of suffering fortification intensity earthquakes，the internal forces of ring cables presented a lower change rate，basically less than 10%． However，their internal forces were significantly changed after the action of rare earthquakes，even totally loosed in some cables． The pretension loss was obviously decreased in those models adopting the elastic design under 8 degree fortification intensity earthquake．