Sponsor
Portland State University. Department of Civil & Environmental Engineering
First Advisor
Peter Dusicka
Term of Graduation
Winter 2025
Date of Publication
1-23-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (Ph.D.) in Civil & Environmental Engineering
Department
Civil and Environmental Engineering
Language
English
Subjects
Analytical Equation Modeling, Earthquake-Resistant Structures, Full-Scale Shake Table Experiments, Mass Timber, Nonlinear Numerical Modeling, Recentering Rocking Structural Systems
Physical Description
1 online resource (xxix, 193 pages)
Abstract
The growing need for structural earthquake resiliency, coupled with increasing demands for environmentally sustainable construction, has driven architects and engineers to emphasize the importance of earthquake-resistant mass timber multistory construction in regions prone to high seismic activity. With advancements in building technologies, cross-laminated timber (CLT) has emerged at the forefront of this movement by unlocking new potentials for urban development.
Motivated by the aforementioned demands, this PhD dissertation investigated lateral behavior and earthquake response of a novel lateral force-resisting structural system, known as Floor Recentering Rocking Core (FLR-ROCR). FLR-ROCR is a low-damage recentering mass-timber system that leverages restoring interactions between rocking core walls and floor diaphragms to deliver a recentering mechanism. In contrast to previous recentering systems, FLR-ROCR is designed to eliminate the need for post-tensioning configurations. Structural ductility is ensured through hysteretic energy dissipation via plasticity of replaceable U-shaped Flexural Plates (UFPs) integrated within hold-down devices. This innovative design enables the system to facilitate rapid post-earthquake recovery by effectively responding to large earthquake demands.
First, a brief discussion of theoretical foundations of the basic mechanics of FLR-ROCR is presented. Performance states are identified within the elastic zone, and the overall recentering and hysteretic behavior of the system are evaluated using preliminary findings from numerical cyclic pushover analysis, and simplified analytical equations. To validate the analytical and numerical analysis, the findings are compared with the results from full-scale cyclic quasi-static experiments, conducted on a single-bay one-story CLT specimen.
Then, a more comprehensive version of the system mechanics is elaborated by developing in-depth analytical equations supporting the theoretical expectations. Two design setups are outlined as potential configuration alternatives, suitable for incorporating FLR-ROCR in architectural plans of core-layout buildings. Analytical equations are developed for each configuration to investigate both the component- and the system-level performance in multistory buildings. All performance and damage states (i.e., limit states), within both the elastic and plastic zones, are identified and boundary conditions corresponding to each limit state are determined. A more advanced numerical technique is further presented to model nonlinearity of the CLT wall fibers and evaluate limit states within the plastic zone. The results from the analytical equations and numerical nonlinear cyclic pushover-analysis are discussed for a 5-story building example incorporating both configuration setups.
Finally, the earthquake response of FLR-ROCR is investigated through a series of full-scale shake-table experiments on a single-bay one-story CLT specimen. The specimen is subjected to eleven simulated ground motions, including scaled records of 2010 Maule Chile (8.8Mw) and 2011 Tohoku-Oki Japan (9.1Mw) subduction megathrust earthquakes. Advance numerical nonlinear dynamic analyses are performed on the specimen model. White-noise and free-vibration tests are conducted to estimate the first-mode dynamic characteristics of the specimen for both linear-elastic and bilinear-elastic response segments. System-level performance is further investigated by focusing on earthquake response, recentering performance, and ductility levels for both the system and UFPs. Eventually, low-damage performance of the system, the rocking contribution to the system behavior, and the influence of vertical inertia on the response are evaluated.
Rights
© 2024 S. Taban Hajimirza
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
Persistent Identifier
https://archives.pdx.edu/ds/psu/43145
Recommended Citation
Hajimirza, S. Taban, "Structural Earthquake Resiliency of Rocking Core Systems with Floor Enabled Recentering" (2025). Dissertations and Theses. Paper 6770.
