ANALYSIS OF SEISMIC RESPONSE AND OVERTURNING RESISTANCE OF ROCKING DOUBLE-DECK BRIDGE SYSTEM

Double-deck viaducts based on traditional ductility design are vulnerable to earthquake-induced damage. To control the seismic damage, a double-deck bridge is developed with the lower floor designed as a rocking structure. To investigate the dynamic response of the rocking bridge, an analytical model of rigid bodies is derived through the Lagrange method and momentum conservation law. The seismic response analysis and parametric analysis adopted structural parameters such as the size and dimension parameter of columns are performed using this model. The overturning resistance of the rocking double-deck bridge is estimated qualitatively and quantitatively with a mathematical model of Ricker wavelets. The results show that the rocking double-deck bridge with dimension in practice can satisfy the seismic design demand of the E2 earthquake according to the seismic design code of bridges in China. However, the rocking bridge is more prone to overturn under near-fault ground motions with a high amplitude velocity pulse. The overturning acceleration spectra and overturning modes of a rocking double-deck bridge system were obtained due to Ricker wavelets. The rocking bridge is more stable with the larger slenderness and size of columns.