Seismic Behavior of Older Steel Structures

Riveted steel connections were used throughout most of the United States for many years. The connections were commonly encased in massive but lightly reinforced concrete for fire protection. These older structures were designed with little or no consideration of seismic behavior, and today these buildings sometimes require seismic rehabilitation and retrofit, but little information regarding this behavior is available. The present paper provides information regarding the seismic performance of these older steel structures. An experimental study which evaluates the seismic behavior of subassemblages with T-stub and clip angle connections is described in detail. The results are analyzed. The strength, stiffness and ductility of the connections are shown to be related to the properties of the steel and the concrete, the mode of failure of the connection, and the concrete encasement. The hysteretic behavior, energy dissipation and deformation capacity of the connections are shown. Approximate models for predicting the strength, stiffness, and deformation limits are presented as practical implications of the research.