Abstract
This paper proposes a rigorous, reliable and efficient minimum cost design method for substructures of seismic-isolation bridge systems considering initial construction cost and repair cost caused by a huge earthquake. The special characteristic values for nonlinear dynamic hysteresis of seismic-isolation bearings, piers and pile foundations are dealt with as the design variables. The relationships between least initial construction costs of rubber shoe, RC pier, RC pile foundation and the corresponding design variables are introduced by using suboptimization processes. The repair cost of each segment is evaluated by considering damage factor, repair cost factor and least initial construction cost of the segment. The estimation formula of maximum horizontal response displacement at each segment is introduced efficiently as the function of design variables by the Experimental Design Method. The cost minimization problems of bridge systems are solved quite efficiently by using a convex approximation concept and the Lagrangian Dual Method. The effects of the horizontal displacement constraints on the minimum cost of bridge systems are also investigated.
