Geometric nonlinearity of long-span suspension bridge mainly comes from three aspects:the cable sag effect
the beam-column effect and the large displacement caused by large changes in the structural geometry.Considering the particularity of seismic ground motions
the amplitudes of high-frequency components of which are usually larger than the low-frequency components
it is difficult to make qualitative judgments of the effects of geometric nonlinearity for the long-span suspension bridge under earthquakes. The existing research about the effects of geometric nonlinearity on the long-span bridges focuses on the cable-stayed bridges
and conflicting results can be seen.In this paper
the comparative analysis of the effects of geometric nonlinearity on two typical symmetric and asymmetric long-span suspension bridges are carried out under seismic ground motions with progressively increased magnitudes for four types of sites. The levels of the geometric nonlinear effects on the responses of long-span suspension bridges and corresponding reasons are investigated and some suggestions are offered.