Effects of Random Properties on the Stability and System Reliability of Steel Frames

This paper studies the effects of random properties on the strength and system reliability of steel frames controlled by frame stability. Probabilistic simulation is used to analyze the behavior of three structures—a low-rise industrial frame; a grain storage bin; and a two-story, two-bay frame. OpenSees is used to perform the non-linear structural analyses within a probabilistic simulation code. The probabilistic analyses consider randomness in yield strength, elastic modulus, residual stresses and geometric imperfections. The simulation results provide probability distributions of frame strength for various random frame properties. The simulation results are used to calculate system reliabilities and compare them to typical target reliabilities. The results of the analyses provide insight into the relationship between specific failure modes and frame properties. The paper also discusses the difficulties of developing probabilistic codes for system-based design criteria and the need for continued probabilistic simulation of non-linear behavior in steel frames.