Cumulative Damage of Structures Subjected to Response Spectrum Consistent Random Processes

Author: Jeong, Garrett Duane

Year: 1985

Degree: Dissertation (Ph.D.)

Advisor: Iwan, Wilfred D.

Committee Members: Iwan, Wilfred D.; Beck, James L.; Hall, John F.; Caughey, Thomas Kirk; Knauss, Wolfgang Gustav

Option: Applied Mechanics

DOI: 10.7907/97b3-2427

Abstract

A theoretical analysis of the effect of duration on the damage of structures subjected to earthquakes is presented. Earthquake excitation is modeled as a nonstationary random process. Estimates of the first-passage probability of a simple oscillator are employed to choose modulated Gaussian random processes consistent with a prescribed response spectrum. The response spectrum is assumed to be specified independent of the duration. Expressions for the mean damage of a structure are derived using an approach similar to the Miner-Palmgren rule for failure caused by cyclic loads. The expected damage expressions are then evaluated for a structure subjected to modulated Gaussian random processes of varying duration.

Two types of structures are examined: a steel structure and a reinforced concrete structure. Results are presented for systems with constant linear stiffness and a particular form of softening behavior. The nonlinearity of the softening system is accounted for by statistical linearization. The level of expected damage is found to be a strong function of both the duration of the excitation and the ductility of the response.

Files