Browsing by Author "Benam, Shaghayegh Sadeghzadeh"

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    A parametric study on the influence of boundary frame flexibility in steel plate shear walls
    (2020-01-17) Benam, Shaghayegh Sadeghzadeh; Özçelik, Ahmet Yiğit; Özçelik, Ahmet Yiğit; Altay, Gülay; Müderrisoğlu, Z.; Department of Civil Engineering; Benam, Shaghayegh Sadeghzadeh
    Steel plate shear walls (SPSWs) are known to be a reliable lateral force-resisting system, particularly attractive for high-seismic regions, due to their high lateral strength and stiffness and stable hysteretic behavior. SPSWs comprise thin infill plates that are connected to the beams and columns of the surrounding boundary frame on all four edges. Being the primary element resisting the lateral load, thin infill plates buckle almost immediately when the SPSW is loaded laterally. Despite shear buckling of thin infill plates, thin infill plates exhibit substantial post-buckling strength and stiffness due to a mechanism called tension field action. To take advantage of tension field, the surrounding boundary frame is required to anchor thin infill plates by resisting the diagonal tension forces exerted by thin infill plates due to the formation of tension field and by limiting the inward deflection of thin infill plates to enable them to yield in tension. Pursuant to this goal, it is necessary to capacity-design the boundary frame to ensure thin infill plates yield prior to hinging in the boundary frame. In addition to the capacity design requirement, a stiffness limit for the boundary frame, based on elastic behavior, is provided by design codes to minimize pull-in of boundary frame. Furthermore, for preventing excessive plastic deformation in the horizontal boundary elements (HBEs) a limit for plastic section modulus of HBEs is provided. In this study, a parametric study is undertaken to quantify the effect of boundary frame flexibility (or stiffness) on the development of diagonal tension and the variation of tension stresses in thin infill plates of SPSWs. The web plate thicknesses are chosen, and relevant boundary frame elements are designed according to the forces applied by web plate without considering seismic actions. 27 one story one bay SPSWs with 3 different aspect ratios (ratio between width and length) and 9 different plate thickness using lightest sections for beams and columns are designed following the capacity design principles. Later for each design, 2 additional bigger column sections are assigned while beam sections remained constant. In total, 81 designs are provided. In addition to the capacity design requirements, these designs also fulfill the stiffness requirement given for boundary frame in design codes. Nonlinear pushover analyses are performed using a simplified model known as strip model (validated against experimental data available in literature) representing the cyclic behavior of thin infill plates. It is observed that column stiffness does not affect the distribution of the stresses in the web plates. Additionally, in pushover analysis it is observed that the capacity design method underestimates the shear forces. Results showed that the accumulation of plastic deformation at the mid- span of the HBE is critical for designs with aspect ratios of 1 and web plates with thickness less than 1.3 mm. Finally, the closed-form expression for uniformity of the stresses in the web plates is also obtained as a function of flexibility of beams and columns, aspect ratios and drifts.