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Reinforced Concrete Shear Walls with Improved Self-Centering and Damage Resistance Properties: Experimental Testing and Numerical Modeling
- Author / Creator
- Tolou Kian, Mohammad Javad
Performance objectives in the seismic design of reinforced concrete (RC) buildings require buildings to survive their maximum considered earthquakes (MCE) with a low probability of total or partial collapse. Often, RC structures require costly retrofitting or demolition and reconstruction after the MCE. A building structure shall also withstand its design basis earthquake (DBE) with a low likelihood of causing life-threatening injuries to the individuals inside or outside.
The current research aims to improve the post-earthquake state of multi-story RC shear walls to decrease their rehabilitation costs after strong earthquakes. Current building codes require that essential structures such as hospitals remain serviceable after strong earthquakes. However, post-earthquake serviceability is not necessary for non-critical structures, such as apartments, which often comprise most buildings in every city. According to current seismic codes, the damage of RC structures can be characterized through their permanent drift ratios and concrete damage. These damage indicators are also intercorrelated to some degrees. For example, higher permanent drift ratios correspond to larger flexural crack openings in shear walls. One option to decrease these damage indicators is to use innovative materials and details with improved performance compared to conventional concrete and steel reinforcement.
In this study, the performance of three innovative shear walls is investigated through experimental testing. In this regard, the cyclic response parameters of the innovative walls are investigated and compared with the response parameters of a conventional RC wall designed to the latest seismic guidelines. Then, the following response parameters of the walls were compared between the conventional and innovative walls – failure mode, permanent drift ratio, concrete damage, stiffness, strength, and energy dissipation.
High-performance reinforced cementitious composites, such as engineered cementitious composite (ECC) and steel fiber reinforced concrete (SFRC) were used to minimize the damage in concrete. Also, to promote self-centering, shape memory alloy (SMA) bars, glass fiber reinforced polymer (GFRP) bars, and high-strength steel strands were used in the innovative walls. It was shown through experimental testing that the drift ratio recovery of a conventional RC shear wall could be improved by more than 90% when some of the longitudinal steel reinforcement of the wall is replaced with self-centering reinforcement.
In the next stage of the study, analysis models of the tested specimens were developed using finite-element methods and were verified with the obtained experimental results. Then, the models were used to study the response of large-scale innovative RC shear walls under cyclic and seismic loads. It was shown that the inelastic rotational capacity in the innovative and conventional RC walls is comparable. The study also showed that the extent of the plastic hinge region in steel-GFRP reinforced walls could be larger compared to conventional RC walls, while it is generally smaller in steel-SMA reinforced and partially post-tensioned concrete walls.
The results from this study demonstrate the feasibility of using innovative materials and details in the design of damage-resistant RC shear walls. It is expected that the analysis models and the design insights produced as part of this investigation assist engineers and building owners toward the adoption of high-performance materials in RC shear walls. The use of high-performance materials in shear walls can lead to more sustainable building structures, which require smaller amounts of time and money for repairing. Also, these buildings are less likely to need demolition and reconstruction after strong seismic events.
- Graduation date
- Spring 2020
- Type of Item
- Doctor of Philosophy
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