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State Route 99 Alaskan Way Viaduct Replacement Program
At a diameter of 57.5 feet, the SR 99 (Alaskan Way) Tunnel was the largest diameter bored tunnel in the world upon completion in 2015. Located in a highly active seismic region, the tunnel replaced the aging double-deck SR 99 Alaskan Way Viaduct that was damaged in the 2001 Nisqually earthquake in downtown Seattle. Because the viaduct plays such a major role in sustaining the local economy and maintaining the ability to travel through Seattle, the deteriorating viaduct was required to remain fully operational during the construction of the tunnel. The bored tunnel is more than 9300 feet long and it navigates through variable glacially over-consolidated soil deposits with an overburden as deep as 215 feet and is subjected to groundwater pressures as high as seven bars. This presentation will describe the technical criteria for the bored tunnel and discuss engineering challenges associated with the liner that has a large diameter to thickness ratio in addition to a large tunnel diameter. The focus will be on the efficient approach for conducting nonlinear dynamic time history analyses for the seismic design and the technique to demonstrate that the tunnel satisfies the stringent seismic performance objectives for two levels of design earthquakes with 108-year and 2500-year return events.
Presented by: Yang Jiang, PhD, P.E., S.E., HTNB
Little Island is a new landmark public park project in New York City that is only possible thanks to the latest digital, parametric, and scripted designs along with the digital fabrications and offsite assemblies. In the presentation, how the engineer worked with the other design team members to come up with unique solutions for complex geometric requirements will be shown. Also, the collaboration with the contractors will be outlined to make the construction as efficient and fast as possible to overcome various constraints.
Presented by: Yong-wook Jo, P.E., Arup
- Course will award 1.5 hours of continuing education for the live session only.
- Each series registration is per person.
- This will be available as a recording, with no PDH attached.