SEISMIC BEHAVIOR OF OLDER STEEL STRUCTURES

Riveted steel connections were used throughout most of the United Stat es for many years. The connections were commonly encased in massive bu t lightly reinforced concrete for fire protection. These older structu res were designed with little or no consideration of seismic behavior, and today these buildings sometimes require seismic rehabilitation an d retrofit, but little information regarding this behavior is availabl e. The present paper provides information regarding the seismic perfor mance of these older steel structures. An experimental study which eva luates the seismic behavior of subassemblages with T-stub and clip ang le connections is described in detail. The results are analyzed. The s trength, stiffness and ductility of the connections are shown to be re lated to the properties of the steel and the concrete, the mode of fai lure of the connection, and the concrete encasement. The hysteretic be havior, 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.