Date

2022-6

Author

Ün, Elif Müge

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

159
views

463
downloads

Cite This

EBF links are classified into three categories as: short, intermediate and long links in terms of the normalized link length. Short links that primarily yield under shear, are usually preferred in eccentrically braced frames (EBFs) due to their high rotation and energy dissipation capacities. Long links that yield under flexure, can be used in cases where large openings are required for architectural reasons. This thesis investigates different aspects of short and long links in three independent parts. In the first part, the effects of strain hardening ratio (SHR) on the performance assessment of eccentrically braced frame (EBF) buildings with short links were studied by using FEMA P-58 methodology. The numerical model was validated using the pseudo-dynamic test results of the DUAREM structure. Seismic performance of six archetype EBFs with different number of stories and link length to bay width (e/L) ratios were evaluated under design basis earthquake (DBE), maximum considered earthquake (MCE), and collapse level earthquake (CLE). Irreparable residual drift, repair cost and unsafe placards were calculated for SHR ranging between 0 and 0.01. The results showed that the residual interstory drift ratio is more influenced by the SHR when compared with the interstory drift ratio, link rotation angle and story acceleration. The replacement decision was found to depend on the SHR, the number of stories, the e/L ratio, and the seismic hazard. The study demonstrated the strong influence and sensitivity of the repair cost to the SHR. Long link behavior differs from the behavior of short links because the former is governed by flexure and subjected to significant amounts of strength and stiffness degradation. In the second part, a numerical study was undertaken to evaluate the seismic response factors for EBFs with long links using FEMA P695 methodology. Twenty-four EBF archetypes were designed by considering the bay width, number of stories, the link length to bay width (e/L) ratio and column base condition as the variables. Performances of these archetypes were evaluated under maximum considered earthquake (MCE), and collapse level earthquake (CLE). The effects of degradation were studied by considering degrading and non-degrading responses separately. A nonsymmetrical loading protocol for long links was developed in the last part of the thesis. Twenty-four long link EBF archetypes with variable floor plans, bay widths, number of stories and link length to bay width (e/L) ratios were designed according to the US standards. The responses of EBFs under maximum considered earthquake (MCE) and collapse level earthquake (CLE) were obtained by making use of numerical analysis employing degrading link models. The link rotation angle time histories were reduced and converted into a series of cycles and the peaks of the LRA response were identified by using the rainflow counting algorithm. The nonsymmetrical loading protocol was represented as a function of maximum rotation range, which depends on the seismic hazard and e/L ratio.

Subject Keywords

Eccentrically Braced Frames, Strain Hardening Ratio, Short Links, Long Links, Load Protocols

URI

https://hdl.handle.net/11511/97902

Collections

Graduate School of Natural and Applied Sciences, Thesis