DYNAMIC CHARACTERISTICS OF CABLE-STAYED GIRDER BRIDGES

The dynamic characteristics of cable-stayed girder bridges, involving their free vibration and dynamic response to a moving load, are theoretically investigated. The dynamic increment factors of deflection and bending moment in a main girder subjected to a traffic load are calculated from a practical point of view. In the dynamic analysis, a cable-stayed girder bridge may be idealized as a lumped mass system and a moving load on it as one degree of freedom system. To verify the rational aspects of the theory and the analytical procedure of the present study, theoretical results are compared with results obtained in dynamic field tests on toyosato bridge, a cable-stayed girder bridge with span lengths of 80.5, 216.0, 80.5 M. The effect of cable stiffness on the characteristics of the free vibration and nondimensional velocity of a vehicle on the dynamic increment factors are discussed. The impact fractions in the Japanese specification of highway bridges are investigated comparing with the dynamic increment factors calculated herein. /TRRL/