Rectangular SC wall piers: Summary of seismic behavior and design

Steel plate composite (SC) wall piers are composed of two steel plates on both sides of a concrete infill. Composite action between the steel plates and concrete infill is achieved using shear connectors and tie bars. The tie bars also provide structural integrity by connecting the two steel plates together. SC wall piers do not have any flange walls, cross walls, or boundary elements. Their seismic response and lateral load capacity are governed by the in-plane flexural behavior and capacity of the SC wall cross-section at the base of the wall. The lateral load capacity is reached due to flexural failure in terms of: (i) concrete crushing of the concrete infill in compression, (ii) local buckling of the steel faceplates in compression, and (iii) rupture of the steel faceplates in tension. SC wall piers are composite alternatives to conventional reinforced concrete (RC) shear walls where the steel rebar curtains are replaced by steel faceplates on the exterior surfaces of the concrete walls. This approach expedites construction by eliminating the need for additional formwork and staging of concrete casting. This approach can also provide structural efficiency if the SC wall cross-section is detailed appropriately with adequate shear connectors and tie bars. These elements provide composite action and also restrain the steel faceplates from buckling prematurely (before yielding). Local buckling typically occurs between the base of the steel plates and the first row of shear connectors or ties, which makes this spacing important detailing criterion for SC wall piers. This paper will summarize the results from cyclic in-plane shear tests conducted on SC wall piers. Some of the cyclic lateral load-drift ratio responses are presented along with the typical hysteresis behavior and story drift capacity. Design equations for predicting the lateral load capacity of SC wall piers without boundary elements are compared with the test results.