Geometrically nonlinear analysis of friction pendulum systems under tri-directional excitation

A three-dimensional formulation for a mass sliding with friction on a concave spherical surface is presented and used to describe the behavior of friction pendulum systems under extreme tri-directional excitation. The pro-posed approach accounts for large deformations and includes a procedure for handling the characteristic stop -and-go, or stick-slip, motion of friction-based systems. A set of numerical examples are carried out comparing the results of the proposed formulation with available analytical solutions. Where these are not available, such as in the case of earthquake excitation, the convergence rate of Newton's method and energy balance plots illustrate the accuracy of the computed solutions. Tri-directional earthquake simulations demonstrate the vulnerability of friction pendulum systems to nearly-periodic, and near-fault, long-period ground motions.

Automated summary

A three-dimensional formulation is presented for a mass sliding with friction on a concave spherical surface, which is used to describe the behavior of friction pendulum systems under extreme tri-directional excitation. The proposed approach accounts for large deformations and includes a procedure for handling the characteristic stop-and-go motion of friction-based systems. Numerical examples and earthquake simulations demonstrate the accuracy of the computed solutions and the vulnerability of friction pendulum systems to ground motions.