Report No.: CCEER-99-7

Title: Studies of Seismic Behavior of Steel Base Plates

Authors: Jackie Burda and Ahmad Itani

Date: May 1999

Performing Organization:
Department of Civil Engineering/258
University of Nevada, Reno
Reno, NV 89557


This report summarizes studies conducted on steel base plates and their effect on the overall seismic response and behavior of a steel building. A two part program, experimental and analytical, was carried out to determine the cyclic behavior of column-base plates assemblies under large deformations and the response of a steel building designed with several base plate configurations. Based on this investigation a design procedure that limits the inelastic activity, during severe ground motions, to the steel plate is recommended.

Six one-half scale column-base plates with various plate sizes and thickness were tested under constant gravity load and lateral cyclic deformations. The base plate assemblies were designed according to the recommended design procedure. The test results showed that the column base plate assemblies were able to dissipate significant amount of energy by plate bending. In addition, these tests showed the vulnerability of the welded connection between the column and the base plate. The failure mode for all six columns was the fracture of the weld between the column and base plate.

Nonlinear finite element analyses using ADINA program were conducted on column base plate assemblies to determine the stress distribution profile underneath the base plate. In addition, Drain-3DX program was utilized to determine the seismic response of a four-story building with several base configurations. The base of this building was modeled as fixed, pinned, and semi-rigid to study its effect on the overall seismic response of the building.