NEHRP Clearinghouse

3D-BASIS Nonlinear Dynamic Analysis of Three-Dimensional Base Isolated Structures: Part 2.
Nagarajaiaj, S.; Reinhorn, A. M.; Constantinou, M. C.
National Science Foundation, Washington, DC., February 28, 1991, 146 p.
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The report deals with the development of a comprehensive analytical model and solution algorithm for nonlinear dynamic analysis of three dimensional base isolated structures and the development of computer program 3D-BASIS. A new analytical model and solution algorithm involving the pseudo-force method is developed. New biaxial and uniaxial models of isolation elements are developed. The novelty of the analytical model and solution algorithm is its capability to capture the highly nonlinear frictional behavior of sliding isolation systems in plane motion. Nonlinear behavior is restricted to the base and the superstructure is considered to be elastic at all times. The nonlinear isolation system may consist of elastomeric and/or sliding bearings, linear springs and viscous elements. The solution algorithm consists of the pseudo-force method with iteration. Comparison of the computed results with experimental results is presented for verification. A six story reinforced concrete base isolated structure is analyzed to demonstrate the efficiency of the algorithm.
Earthquake resistant structures; 3D-BASIS computer program; Structural vibration; Springs (Elastic); Algorithms; Mathematical models; Dynamic response; Earthquake engineering; Vibration damping; Stiffness; Displacement; Vibration isolators; Bearings; Nonlinear systems; Dynamic structural analysis