Effect of the primary structure on the seismic response of the cable-net façade

The cable-net supported façade is increasingly used in the modern buildings. In a cable-net façade, the ends of the cables are anchored to the primary structure along its elevation, and the façade's seismic response is triggered by the earthquake-induced vibration of the primary structure. In this regard, the effect of the primary structure should be considered in the seismic response analysis of the cable-net façades. However, such an effect is ignored in most of the preceding research. In this paper, the effect of the primary structure on the seismic response of the cable-net façade is quantitatively studied. A group of cable-net models is subjected to two types of earthquake excitations. First, the ground accelerations are uniformly applied to the cable-net models. In this case, the effect of the primary structure is neglected. Second, the ground accelerations are applied to a series of primary structural models, generating the height-wise non-uniform dynamic excitations for the cable-nets, and the cable-nets are subjected to the non-uniform excitations. In this case, the effect of the primary structure is fully accounted for. A detailed comparison between the two groups of results is conducted. It is shown that the primary structure significantly influences the peak response of the cable-net façade, and such influences are strongly affected by the fundamental period ratio (R_T) between the cable-net and the primary structure. For R_T ≤ 0.6, it would be overly conservative to neglect the effect of the primary structure, while for R_T ≥ 0.8 (especially at R_T ≥ 1.0), it is unsafe to neglect such effects. If R_T is around 1.0, the mid-span displacement of the cable-net façade under the non-uniform excitation (considering the effect of the primary structure) could be twice as large as that under the uniform excitation. Meanwhile, the tension of cables could exhibit a 20% increase due to the effect of the primary structure. The results obtained from different types of primary structures (varied lateral force resisting mechanism) are similar. From this study, it is inappropriate to ignore the effect of the primary structure in analyzing the seismic responses of the cable-net façades. This indicates the drawback of many preceding studies wherein the effect of the primary structure is neglected, and shows the necessity of developing a proper approach to account for this effect in the design of the cable-net façades.