OPTIMUM ASEISMIC DESIGN OF TOWER AND PIER SYSTEMS OF LONG SPAN SUSPENSION BRIDGES.

Optimization technique was applied to tower and pier systems subjected to seismic external forces. Almost the same optimal solutions were acquired by two different methods: actual data technique with average answer spectrum in input, and probability method using density coefficient of power spectrum. Optimal aseismic design was found to be greatly influenced by modulus of elasticity of the foundation on which the tower or pier system of the bridge is constructed. If the modulus of elasticity is small, then the displacement of pier top is limited; if it is large, then the design should prevent pier falling down and tower buckling.