Computational Investigation of Tunable Steel Plate Shear Walls for Improved Seismic Resistance
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Steel plate shear walls (SPSWs) are popular lateral force resisting systems whose practical applications range from high seismic regions to medium and low seismic areas and wind load applications. The factors which make SPSW attractive include its energy dissipation capacity, excellent ductility, constructability, speed of construction compared to concrete shear walls, reduced architectural footprint compared to concrete shear walls, and increased inelastic deformation capacity as compared to braced frames. The principle behind current SPSW design is that the post-buckling tension field capacity of the thin web plate is proportioned to resist the full lateral load. The resulting web plate is typically quite thin, buckles at low loads, possesses low stiffness, and does not provide resistance when the lateral loads are reversed until the tension field engages in the opposite direction. To compensate for these shortcomings, moment connections are required at the beam to column connections to improve energy dissipation, increase stiffness, and provide lateral resistance during load reversal. The resulting SPSW designs with very thin web plates, moment connections, and beams and columns significantly larger than comparable braced frames, can result in inefficient structural systems. The objective of this work is to develop steel plate shear wall systems that are more economic and efficient. In order to achieve this, approaches like shear connections between beams and columns, allowing some yielding in columns and increasing plate thicknesses were attempted. But these approaches were not effective in that there was no reduction in the amount of steel required since stiffness controlled the designs. This necessitated the creation of tunable steel plate shear wall systems in which strength and stiffness could be decoupled. Preliminary analyses of seven steel plate shear wall systems which allow tunability were conducted and two configurations namely circular holes and butterfly shaped links around the perimeter, that showed promising results were chosen. The solid plate in the middle of the panel contributes significant pre-yield stiffness to the system while the geometry of the perimeter perforations controls strength and ductility. An example panel was designed using the two approaches and compared to panels designed using current SPSW design methods. The proposed configurations resulted in improved overall performance of the system in terms of energy dissipation, stable hysteresis, required less steel and no moment connections between beams and columns. This was also observed from the parametric study that was performed by varying the thickness of the web plate and the geometry of the configurations. Thus it was concluded that the two proposed configurations of cutouts were promising concepts that allow separate tuning of the system strength, stiffness and ductility and could be adopted in any seismic zone for improved seismic resistance.
- Masters Theses