Improved performance-based plastic design method for post-tensioned connection systems

• Published in: Engineering structures 2022-03, Vol.255, p.113931, Article 113931
• Main Authors: Moradifard, R., Alibazi, A., Shiravand, M.R., Gholami, M.
• Format: Article
• Language: English
• Subjects: Cables; Columns (structural); Ductility; Earthquake damage; Earthquakes; Energy dissipation; Limit states; Nonlinear time-history analysis; Performance-based plastic design; Plastic design; Post-tensioning; PT-steel connections; Retrofitting; Seismic activity; Stiffness; Stress ratio; Yield stress
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2022.113931

•The present study developed a PBPD system with a method of designing PT connections with top and bottom angles.•The self-centring connection systems satisfy the maximum design drift at different levels of hazard.•A new design approach has been presented for structures with PT Steel connections.•In PBPD method, the need for drift control after the design has been eliminated. Performance-based plastic design (PBPD) was initially proposed as a method for retrofitting existing structures. The PBPD method gradually became a general approach for designing new structures. This method is a direct method to obtain design base shear and leads to design structures being more economical compared to traditional methods. PT connections were developed after the Northridge earthquake. The self-centering could restore the connection to its original position without damage to the beams and columns. High-strength post-tensioned cables are used to restore the structure to its initial position in PT connections. Also, energy dissipaters (for example, top and bottom angles) are used to increase ductility. In this study, a proposed relationship between the ductility (µ), period (T), and response reduction factor (R) is presented for structures with pinching or flag-shaped behavior, and the effect of the parameters on R has been investigated. Also, a new design approach for structures with PT-steel connections with top-and-bottom angles is presented. The results show that R primarily depends on the post-yield stiffness ratio (α), the yield stress ratio (or energy dissipation) (β), ductility (µ), soil type, etc. Nonlinear time-history analysis indicates that designed models based on the proposed approach satisfy drift limits. The results show that the proposed relationship can be quite suitable for designing PT connections using the PBPD approach.