A cable-net roof

    
(a)                                                                                                                 (b)
Fig. 11-11: Cable net roof of the Sichuan Provincial Gymnasium

Cable-net roofs are ideally suited for use with long span structures such as gymnasia. Fig. 11-11a shows half of the cable-net roof used for the Sichuan Provincial Gymnasium, which was built in 1988 and is able to contain over 10,000 seated spectators [11.10].

The stiffness of the cable-net roof was established by prestressing. By applying forces at the ends of prestressing (hogging) cables, tension forces are induced in both carrying (sagging) cables and prestressing cables. The prestressing and carrying cables are normally placed perpendicularly to each other (Fig. 11-11b). The level of prestress applied should ensure that no prestressing cables are slack for any load configuration.