Abstract:
To evaluate the seismic performance of the multi-layer overpass bridge structure easily
and accurately, this paper performed a modal pushover analysis (MPA) on the multi-layer
overpass bridge structure and verified the accuracy of its results. A 3-layer overpass
bridge was used as the research object, and the structural calculation model was
established by the finite element software SPA2000. Modes with a modal mass
participation ratio greater than 1% should be determined first, and the cumulative modal
mass participation ratios greater than 90%. Then a pushover analysis was performed for
each mode to be considered, and structural performance points were obtained by the
capability spectrum method. Seismic response results corresponding to structural
performance points can be obtained by the formula calculation. Finally, response results of
pushover analysis corresponding to each mode were combined by the square root of the
sum of the squares (SRSS) method to obtain the total response result. At the same time,
the nonlinear time history analysis (NL-THA) results of the bridge structure were obtained
by inputting seismic motions into the structural finite element calculation model. The
applicability of MPA on multi-layer overpass bridge structures was evaluated by comparing
response results obtained from MPA and NL-THA. The results show that MPA can reduce
the computational effort compared to NL-THA. The MPA and NL-THA deviations are less
than 20% and 25% in the longitudinal and transverse directions, respectively. The results
of MPA can effectively evaluate the seismic performance of the multi-layer overpass
bridge.
