Civil Engineering

Permanent URI for this collectionhttps://hdl.handle.net/10679/312

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Now showing 1 - 7 of 7

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Behavior of columns of steel plate shear walls with beam-connected web plates
(Elsevier, 2018-10-01) Özçelik, Ahmet Yiğit; Clayton, P. M.; Civil Engineering; ÖZÇELİK, Ahmet Yiğit
Steel plate shear walls with beam-connected web plates (B-SPSWs) are an alternative configuration of steel plate shear walls (SPSWs) where web plates are connected to the beams only. Detaching web plates from columns and introducing simple beam-column connections in B-SPSWs eliminate flexural demands in the columns resulting from web plate tension field action; consequently, the columns of B-SPSWs are designed primarily for axial loads. A recent study, however, showed that the columns of B-SPSWs resist significant flexural demands during earthquake shaking due to differential interstory drifts that result in significant column rotations at floor levels. Typical design methods (i.e., the Equivalent Lateral Force method and Modal Response Spectrum analysis) do not capture these rotations associated with differential drifts that might lead to column instability. A two-phase numerical study is conducted to evaluate the behavior and stability of B-SPSW columns. In the first phase, three-dimensional nonlinear response-history analyses are conducted to investigate the column stability for eighteen B-SPSWs with different geometric characteristics designed following two design approaches. The results suggest that column buckling is a possible mode of failure for one of the design approaches. In the second phase, a parametric study is undertaken to further investigate potential column buckling failure modes in B-SPSW columns and to establish an upper-bound estimate for the column buckling strength reduction due to column rotations at floor levels that are not considered in traditional design approaches.
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Effect of flexural demands in the leaner columns on the column buckling strength
(Earthquake Engineering Research Institute, 2018) Özçelik, Ahmet Yiğit; Clayton, P. M.; Civil Engineering; ÖZÇELİK, Ahmet Yiğit
Leaner columns of steel frames are typically designed for axial load only and they are assumed not to contribute to the lateral stiffness of the system; however, a recent study revealed that under seismic loading leaner columns underwent significant flexural demands due to differential interstory drift demands along the building height that were not observed when traditional design methods were adopted. A parametric numerical study is conducted to quantify the reduction in column buckling strength due to these flexural demands that are not considered in design. An empirical column buckling strength reduction factor that accounts for the reduction in the column buckling strength due to flexural demands is proposed. This reduction factor can be easily implemented with traditional design approaches without considering the flexural demands in the leaner columns explicitly.
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Expeditious strip model for steel plate shear walls with beam-connected web plates
(Elsevier, 2021-09) Özçelik, Ahmet Yiğit; Civil Engineering; ÖZÇELİK, Ahmet Yiğit
Steel plate shear walls (SPSWs) are a robust lateral force-resisting system used in earthquake-prone regions due to their high lateral strength and stiffness as well as stable hysteretic characteristics. One of the configurations of SPSWs is SPSWs with beam-connected web plates (B-SPSWs) in which web plates are connected to beams only to reduce the flexural demands in the columns emerging due to anchoring of the tension field forces in web plates. One of the modeling approaches used to simulate the cyclic behavior of beam-connected web plates in B-SPSWs is the strip model in which web plates are modeled using a series of identical diagonal truss members. Previous research suggested use of at least 10 strips to capture the boundary frame demands in B-SPSWs; however, use of 10 or more strips significantly increases the computational effort. In this study, an expeditious strip model is proposed for beam-connected web plates in which only three strips are used. Instead of adopting identical strips, the cross-sectional area of each strip is arranged such that the boundary frame demands can be estimated accurately. The proposed model is validated against available test data in literature and compared with the other strip models of beam-connected web plates. The results of the study indicate that the proposed model is the superior one as it can capture the cyclic response of beam-connected web plates and boundary frame demands as well as reduce the computation time.
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Seismic design and performance of SPSWs with beam-connected web plates
(Elsevier, 2018-03) Özçelik, Ahmet Yiğit; Clayton, P. M.; Civil Engineering; ÖZÇELİK, Ahmet Yiğit
Steel plate shear walls with beam-connected web plates (B-SPSWs) are an alternative steel plate shear wall (SPSW) configuration in which the web plate edges are detached from the columns to avoid high flexural demands in the columns resulting from tension field action. Releasing the columns from the web plates results in development of a partial tension field instead of the full tension field observed in conventional SPSWs, which changes system behavior and member demands significantly. A numerical study is undertaken to assess the seismic performance of B-SPSWs designed for low-seismic regions. Equations for the web plate lateral strength and the beam axial force, shear force, and moment demands are provided. Following two design approaches, eighteen B-SPSWs possessing different geometric characteristics are designed based on the provided equations. Each B-SPSW is subjected to forty ground motions representing two seismic hazard levels. The seismic performance of these B-SPSWs is evaluated based on maximum interstory drifts, member demand-to-capacity ratios, and beam-column connection rotations. The results indicate that B-SPSWs show a promising seismic behavior and may be particularly attractive lateral force-resisting alternatives for regions of low and moderate seismicity. (C) 2017 Elsevier Ltd. All rights reserved.
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Seismic performance assessment of concentrically braced steel frames designed to the Turkish Building Earthquake Code 2018
(Elsevier, 2022-06) Kor, Efecan; Özçelik, Ahmet Yiğit; Civil Engineering; ÖZÇELİK, Ahmet Yiğit; Kor, Efecan
The Turkish Building Earthquake Code 2018 (TBEC 2018) came into force in 2019 and superseded the previous code, the Turkish Earthquake Code 2007 (TEC 2007). Compared to TEC 2007, TBEC 2018 includes new design approaches as well as significant changes in the design of steel structures which are likely to notably affect the seismic design and performance of concentrically braced frames (CBFs). This study aims to quantify the seismic performance of CBFs designed to TBEC 2018. To this end, a set of archetypes was designed, covering a wide range of building heights, bay widths, and seismic hazard levels. Nonlinear numerical models of the archetype buildings were built to perform nonlinear static and dynamic analyses. The seismic performance assessment framework outlined in FEMA P-695 was adopted. The effects of build height, bay width, and seismic hazard levels were investigated and reported. The results of the study revealed that CBFs located in moderate-seismic regions showed acceptable performance while CBFs designed to TBEC 2018 performed poorly in high-seismic regions.
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Strip model for steel plate shear walls with beam-connected web plates
(National Technical University of Athens, 2019) Özçelik, Ahmet Yiğit; Clayton, P.; Civil Engineering; Papadrakakis, M.; Fragiadakis, M.; ÖZÇELİK, Ahmet Yiğit
Steel plate shear walls (SPSWs) are a lateral force-resisting system in which thin infill plates (web plates) are connected to the boundary frame (i.e., beams and columns) along four edges. Despite shear buckling of thin plates upon lateral loading, web plates still provide lateral strength and stiffness in the post-buckling range owing to a mechanism called tension field action. The boundary frame (particularly columns) needs to satisfy stringent strength and stiffness requirements to anchor the inclined forces in web plates resulting from tension field action. An alternative system to conventional SPSWs, steel plate shear walls with beam-connected web plates (B-SPSWs), is proposed in the literature where web plates are connected to beams only. Therefore, high flexural and axial load demands in columns induced by tension field forces are eliminated. However, due to the difference in boundary conditions of web plates, the load path of steel plate shear walls with beam-connected web plates significantly differs from that of conventional SPSWs. In this study, a simplified strip model of beam-connected web plate is proposed to simulate the cyclic behavior of beam-connected web plates. As it is typical and conservative to ignore the compressive strength of strips, strip models underestimate the strain energy dissipated under cyclic loading. An equation for the compressive strength of strips is proposed to accurately capture the energy dissipation capacity of beam-connected web plates. A three-way comparison between the proposed strip model, a strip model from the literature, and a validated continuum model is provided. The results reveal that the proposed strip model is capable of successfully estimating the boundary frame demands, lateral load capacity, and energy dissipation of beam-connected web plates.
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Tension field inclination angle in steel plate shear walls with beam- connected web plates
(National Technical University of Athens, 2019) Özçelik, Ahmet Yiğit; Clayton, P.; Civil Engineering; ÖZÇELİK, Ahmet Yiğit
Steel plate shear walls (SPSWs) are an efficient lateral force-resisting system with thin infill plates, main elements resisting the lateral force, connected to beams and columns on all four edges. Upon lateral loading, thin infill plates (also known as web plates) buckle almost immediately; however, the lateral stiffness and lateral strength of SPSWs are maintained due to a mechanism called tension field action. Steel plate shear walls with beam-connected web plates (B- SPSWs) are an alternative SPSW configuration where the web plates are detached from columns and connected to beams only. As opposed to conventional SPSWs where the full tension field is observed, a partial tension field is developed in the web plates of B-SPSWs due to the difference in connectivity which alters the system behavior significantly. As SPSWs are typically modeled using simplified strip models in which the accurate determination of the tension field inclination angle is of paramount importance, an analytical study is undertaken to quantify the partial tension field inclination angle. Using validated finite element models, beam-connected web plate behavior is characterized, and an equation is proposed for the partial tension field inclination angle.

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