PSI - Issue 64

M. Esmaelian et al. / Procedia Structural Integrity 64 (2024) 2091–2100 M. Esmaelian/ Structural Integrity Procedia 00 (2024) 000 – 000

2094

4

3. Feasibility of Self-Centering for Segmental Columns Using Prestressed Fe-SMA Conventional segmental columns prestressed with tendons require heavy equipment for prestressing, and their behavior under cyclic loading needs further investigation. In this study, a self-centering segmental column system prestressed with Fe-SMA bars is proposed and the effect of various parameters on the cyclic behavior of such columns is investigated. To evaluate the proposed column system, three-dimensional (3D) FE models of segmental columns are developed and validated based on the experimental test (JH1) performed by Hewes and Priestley (Hewes & Priestley, 2002). This section describes the modeling approach and design details of the proposed segmental column system and the JH1 column used to validate the modeling. 3.1. Model Description Figure 3 (a) shows the design details of the tested column JH1, which consists of four 610 mm diameter segments with an aspect ratio of 6. The bottom segment of the column is 610 mm high and the top segments are 900 mm high, all connected by an unbonded post-tensioned tendon. The upper segments are reinforced with 8 ⌀ 12.7 discontinuous bars and confined by 9.5 mm stirrups spaced 75 mm apart. The lower segment has no bars and is confined only by a steel jacket of 6 mm. The central tendon has an area of 2665 mm 2 and is post-tensioned to 1009 MPa, resulting in a PT ratio of 19.9%. With a gravity load ratio of 6.6%, a total axial load ratio of 26.5% is achieved. The column was tested under constant axial load and quasi-static lateral load up to 3% drift ratio as described in (Hewes & Priestley, 2002). The proposed segmental column system prestressed with Fe-SMA bars shares similar design details in terms of column size and segment confinement. However, the steel jacket in the bottom segment has been replaced with spirals to make the proposed design more efficient and easier to apply. 14 ⌀ 18 unbonded and bonded Fe-SMA bars are used to prestress the column. These bars are evenly distributed around the perimeter of the column, resulting in a longitudinal reinforcement ratio of 1.22%. The recovery stress of each Fe-SMA bar is 300 MPa, resulting in a total SMA-PT loading ratio of 7.5% on the column. Additional continuous steel reinforcement at the segment joints, called ED bars, are provided to contribute to the energy dissipation capacity of the columns. Ratio of ED bars will be studied in the future parametric study section. Figure 3 (b) shows the schematic design details of the proposed column system.

Figure 3 Design details of (a) JH1 (reprinted from (Hewes & Priestley, 2002)) (b) proposed segmental column system