Numerical Simulation of the New Post Tensioned Column Base with Bolted T-stubs

Abstract

A new post tensioned column base connection for earthquake resistant steel moment resisting frames (MRFs) is introduced. The proposed post tensioned column base consists of high strength PT bars, reinforcing plate and bolted T-stubs. In this connection, the PT bars provide restoring force for self-centering behavior while the T-stubs dissipate energy by yielding. By using this connection, the plastic hinge in the column bases is removed and plastic deformation is concentrated in energy dissipation device. An analytical model based on fibre elements was developed with OpenSees to model column base connection. Accordingly; the model accurately predicts the expected behavior of the new proposed column base connection under cyclic loading. The proposed connection provides similar characteristic behavior of the post tensioned column base. To investigate the cyclic behavior of the PT column base connections, a series of the PT column base connection were subjected to axial load and cyclic lateral displacements. Analysis variables included PT bar diameter, initial post tensioning force and dissipation device size. Results showed that under large earthquake rotations, this connection could reduce or eliminate the plastic rotation by its self-centering behavior as well as providing required strength and stiffness.