EC8-based seismic design and assessment of self-centering post-tensioned steel frames with viscous dampers

Abstract

Original citation:Tzimas, Angelos S., Dimopoulos, Athanasios I. and Karavasilis, Theodore L.. (2015) EC8-based seismic design and assessment of self-centering post-tensioned steel frames with viscous dampers. Copies of full items can be used for personal research or study, educational, or not-forprofit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. ABSTRACTThis paper focuses on seismic design and assessment of steel self-centering moment-resisting frames (SC-MRFs) with viscous dampers within the framework of Eurocode 8 (EC8). Performance levels are defined with respect to drifts, residual drifts and limit states in the post-tensioned (PT) connections. A preliminary pushover analysis is conducted at the early phase of the design process to estimate rotations and axial forces in post-tensioned (PT) connections instead of using approximate formulae. Different designs of an SC-MRF with viscous dampers are considered to investigate all possible scenarios, i.e. use of dampers to achieve drifts significantly lower than the EC8 drift limit; to significantly reduce steel weight without exceeding the EC8 drift limit; or to reduce steel weight and achieve drifts lower than the EC8 drift limit. Nonlinear dynamic analyses using models capable of simulating all structural limit states up to collapse confirm the minimal-damage performance of the SCMRFs. It is shown that the use of the preliminary pushover analysis makes the design procedure very accurate in predicting structural and non-structural limit states. Supplemental damping along with strict design criteria for the post-tensioned connections are found to significantly improve the seismic performance of the SC-MRFs. Moreover, the paper shows that SC-MRFs with viscous dampers have superior collapse resistance compared to conventional steel MRFs even when the SC-MRF is significantly lighter than the conventional MRF.

Collapse risk and residual drift performance of steel buildings using post-tensioned MRFs and viscous dampers in near-fault regions

“…When loading is reversed, the connection begins to unload until the gap closes. Equations to calculate S 1 to S 3 and θ 1 to θ 3 are provided in (Tzimas et al 2015). Fig.…”

“…3a shows the plan view of a 5-storey, 5-bay by 3-bay prototype steel building having two identical perimeter seismic-resistant frames in the 'x' plan direction. The study focuses on one perimeter seismic-resistant frame, which is designed as a high ductility class MRF, MRF with viscous dampers, SC-MRF, and SC-MRF with viscous dampers using existing design procedures (Garlock et al 2007;Kim and Christopoulos 2008b;Tzimas et al 2015). These different designs of the perimeter seismic-resistant frame have the same beam and column cross-sections.…”

“…The parallel combination of hysteretic and viscous energy dissipation along with a friction slip mechanism in series connected to the viscous energy dissipation mechanism were found to achieve high levels of seismic performance (Kam et al 2010). The parallel use of viscous dampers and steel SC-MRFs was found capable to simultaneously control inelastic deformations, peak storey drifts, and residual storey drifts (Tzimas et al 2015).…”

Collapse Risk Evaluation of Self-Centering Steel MRFS With Viscous Dampers in Near-Fault Regions

“…When loading is reversed, the connection begins to unload until the gap closes. More details about the connection behavior can be found in [32].…”

“…The parallel combination of hysteretic and viscous energy dissipa-tion along with a friction slip mechanism in series connected to the viscous energy dissipation mechanism were found to achieve high levels of seismic performance for self-centering systems [31]. Tzimas et al [32] also proposed a new seismic design procedure for SC-MRFs equipped with viscous dampers in the framework of EC8 [12].…”