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Thesis Defence: Experimental Study of Shape Memory Alloy (SMA) Connection in Precast Concrete Shear Walls for Seismic Applications
August 15 at 9:30 am - 1:30 pm
Deepak Saud, supervised by Dr. Lisa Tobber and Dr. M. Shahria Alam, will defend their thesis titled “Experimental Study of Shape Memory Alloy (SMA) Connection in Precast Concrete Shear Walls for Seismic Applications” in partial fulfillment of the requirements for the degree of Master of Applied Science in Civil Engineering.
An abstract for Deepak Saud’s thesis is included below.
Defences are open to all members of the campus community as well as the general public. Please email lisa.tobber@ubc.ca to receive the Zoom link for this defence.
ABSTRACT
The jointed post-tensioned Precast Concrete (PC) shear walls are designed to rock around their base and self-centre themselves upon unloading. One way to enhance ductility is by allowing controlled rocking at the wall-to-foundation connection using unbonded Post-tensioning (PT) tendons, and mild steel rebars as energy dissipators in PC shear wall buildings. However, this jointed connection system is complex to build and lacks adequate ductility for longer walls. Also, the jointed connection with grouted metal duct connections with deformed steel rebar as dowel rebar has limited ductility. A particular unknown exists about the force deformation capacity of grouted dowel connection.
This thesis aims to investigate the local behaviour of the PC wall through a new ductile connection using shape memory (SMA) rebar and couplers. The study started with a numerical study to investigate the effects of various parameters (aspect ratio, axial load ratio, rebar types, and vertical reinforcement ratio) on the seismic response of the concrete shear walls reinforced with SMA rebars at the base. Fifty-four finite element models of the RC walls reinforced with SMA rebars and steel were developed. The results were analyzed to evaluate the seismic behaviour of SMA RC walls, which improved the understanding of SMA PC walls. Additionally, four coupler pullout tests and seven pullout tests of rebar in concrete blocks were carried out to investigate the effectiveness of the anchorage of the SMA rebar connected with the coupler and surrounding grout within a metal duct. The test results ensured the rebar was stressed beyond the superelastic strain range, leading to ductile failure and low slippage. Finally, three small-scale wall-to-wall connection test specimens were constructed and tested under monotonic loading to investigate the force-deformation response of the proposed anchoring system for SMA-reinforced PC wall-to-wall intersections. The result shows that specimens with the proposed connection consisting of SMA and couplers present higher yield displacement, yield and ultimate load capacity, and hardening ratio compared to the specimens with steel and couplers.
