Song, Biao;
(2022)
Advancing performance-based design and assessment of exposed column base plates and welded column splices in steel moment resisting frames.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Exposed column base plate (ECBP) and welded column splice (WCS) connections are critical load-carrying structural connections and are commonly used in steel moment-resisting frames (SMRFs). However, they have received relatively lower research attention than welded beam-to-column (WBC) connections, leaving several relevant aspects of their performance and their effects on the overall seismic performance of SMRFs not well investigated. For instance, although the current design approach for ECBP connections is relatively well-established from a mechanistic standpoint, the reliability of such designed connections (i.e., the structural performance of ECBPs at the design level) is not as well understood. Therefore, some prospective refinements to the current approach may be developed to ensure acceptable and consistent failure probabilities across the various components of the ECBP connections. In the context of WCS connections constructed before the 1994 Northridge earthquake (i.e., pre-Northridge WCSs), their potential fracture due to earthquake shaking has been recently revealed in some research studies. However, these studies did not take advantage of recent advancements in performance-based earthquake engineering (PBEE), and made several simplifying assumptions for practical purposes. Some refinements and research tools within the PBEE framework may be required to more accurately estimate the fracture demand and capacity distributions, and the associated fragility and risk of pre-Northridge WCSs. This doctoral dissertation attempts to address these mentioned issues in a rigorous manner. Specifically, this dissertation presents the following research studies: 1. Detailed reliability analysis of ECBPs designed as per the current design method and two modified approaches (improved from the current one) for a set of 59 design scenarios subjected to combinations of gravity, wind, and seismic loads. This also includes the Monte Carlo sampling to characterize the uncertainty sources in the load, material properties, component geometry, and demand/capacity models for various components within the connection. 2. Refined probabilistic fracture fragility assessment of pre-Northridge WCSs, accounting for the seismic demand and fracture capacity uncertainties. Optimal ground-motion intensity measures, the effect of vertical ground accelerations, and the WCS capacity uncertainties are included to improve the fracture fragility estimation. 3. Expanded fracture fragility and risk assessment of pre-Northridge WCSs in near-fault regions to address the effect of pulse-like ground motions on the distribution/increase of WCS seismic demands. Near-source probabilistic seismic hazard analysis is conducted to facilitate the fracture risk assessment. The findings of the first study can contribute to the better scientific knowledge of reliability-based design and assessment of ECBP connections in SMRFs, whereas the last two studies can help better understand the fracture risk of WCS connections in SMRFs, and inform the planning of retrofitting strategies.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Advancing performance-based design and assessment of exposed column base plates and welded column splices in steel moment resisting frames |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2022. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10142313 |
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