What Is a Steel Plate Shear Wall (SPSW)?
A steel plate shear wall is a seismic lateral system where thin steel infill plates, framed by boundary beams and columns, resist lateral loads through diagonal tension-field action. In an earthquake, the plates yield in tension along diagonal bands — enormous energy dissipation from very thin material. SPSWs deliver high stiffness and ductility with less material than concrete shear walls, popular in high-seismic high-rises and retrofits.
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How tension-field action works
The thin plate cannot resist compression (it buckles immediately), but in tension it is remarkably strong. Under lateral load, the plate develops diagonal tension bands — like the diagonal in a truss — carrying the shear. The boundary columns and beams anchor the tension field and must be designed for the forces the yielded plate delivers to them (capacity design — the plate is the fuse). Perforated or slit plates tune stiffness where openings are needed.
Advantages and applications
Very high ductility (R=7-8), high initial stiffness (drift control), thin profile (more leasable floor area than concrete walls), and fast erection (plates weld or bolt to the boundary frame). Used in new high-rise construction in seismic zones and as seismic retrofits — SPSW panels can be inserted into existing frames. The trade-off: the boundary elements get large (they collect the tension-field forces), and the plate-to-frame connections need careful detailing.
Design requirements
AISC 341 governs: plate thickness and yield strength selection, boundary element design for the tension-field forces (including the vertical component that compresses columns), connection of the plate to the boundary (welded or bolted, designed for the plate's expected yield strength), and limitations on openings (which interrupt the tension field — reinforce around them). Special inspection covers plate material, weld quality, and bolt pretension.
The bottom line
SPSWs resist earthquakes through diagonal tension in thin steel plates — high ductility and stiffness, thin profile. Design boundary elements for the tension-field forces per AISC 341.
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