Assessment of Three Viscous Damping Methods for Nonlinear History Analysis: Rayleigh With Initial Stiffness, Rayleigh With Tangent Stiffness, and Modal

Abstract eng:
This paper discusses three methods for applying linear viscous damping at the global level in nonlinear time history analysis: (1) Rayleigh damping proportional to the mass and initial stiffness matrices, (2) Rayleigh damping proportional to the mass and tangent stiffness matrices, and (3) modal damping through the dynamic nonlinear modal analysis method, also known as fast nonlinear analysis (FNA). The effect of global stiffness changes on structures modeled with the three methods is studied and compared. This paper showcases one of the limitations of Method 1 (Rayleigh damping with initial stiffness): sensitivity to the modeling of localized nonlinearity, such as frame elements that are sub-divided around the nonlinear hinges. As the sub-division around the nonlinear hinges become smaller, the damping forces in the nonlinear elements become larger and can have a significant effect on the computed forces in neighboring elements as well as global behavior. In contrast, the latter two methods are insensitive to the modeling of localized nonlinearity. Finally, the results of nonlinear response history analyses using each method is compared for a 30-story building model used for performance-based design. All structural modeling and analysis is done using the commercial software ETABS 2015. Method 3 (modal damping with FNA) gives similar results to Method 2 (Rayleigh damping with tangent stiffness) for the 30-story building model. The effect of the three methods upon the efficiency of analysis is also compared.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket