SC Solutions was recently honored with two Engineering Excellence awards from ACEC, the American Council of Engineering Companies. The ACEC California’s 2014 Engineering Excellence Awards & Legislative Reception was held on Monday, February 3, 2014 at the Hyatt Regency in Sacramento. The two awards presented to SC Solutions were both Honor Awards. The two projects receiving awards were:

Devil’s Slide / Tom Lantos Tunnels

Devil’s Slide Tunnel is a twin tunnel constructed along US Route 1 in California for an estimated cost of $190M. It is approximately 4,000 feet long portal-to-portal. The area is underlain by a faulted rock stratum, including the crystalline igneous rock of the Montara Granodiorite and sedimentary rocks of Cretaceous and Paleocene age.

An SC Solutions team worked on this project for several months. SC Solutions performed seismic analysis of the Devil’s Slide Tunnel section to evaluate vulnerabilities of the concrete structure during the design seismic event. Additionally, excavation analysis was carried out to validate the design construction sequence process. Seismic evaluation was conducted using nonlinear time history analysis with multiple support excitations. Nonlinear effects simulated in these models included representation of the construction sequence, global geometric effects, and liner / soil interaction. Specifically, effects of the seismic wave passage on the structural integrity of the tunnel were thoroughly examined.

The main tunnel liner, cross-passage, and the surrounding soil continuum were modeled using solid elements. These high-order elements characterized the bending behavior with a single element layer through the thickness. Connection between the liner and the soil mass was characterized by a series of tangential and longitudinal nonlinear springs with appropriate stiffness. The seismic loading was applied as displacement time history records at the boundaries of soil continuum model. Wave passage effects were considered. Results were computed and evaluated at each tunnel segment, as well as the tunnel to cross-passage connection.

The old U.S. Highway 1 -Devil’s Slide section is now by-passed by the new Tom Lantos Tunnels. The new northbound and southbound tunnels provide a safe, dependable highway between Pacifica and Montara. A ribbon cutting for the new Lantos Tunnels was held on March 25, 2013 with the first vehicles traveling through the new tunnels early the next morning.

Foresthill Bridge Seismic Retrofit

A project tackled by Hassan Sedarat, Wei Li and Joyce Lee with Vince Jacob as Project Manager, the Auburn Foresthill Road Bridge Seismic Retrofit project also received an Honor award. SC Solutions was commissioned to evaluate the seismic vulnerability of the bridge by performing a non-linear time history analysis of a detailed 3-D model of the bridge, which among other capabilities can simulate the buckling of the superstructure elements. The Foresthill Bridge is a 3-span steel truss bridge. The bridge is composed of concrete piers, steel truss with perforated and non-perforated members, and a steel-concrete composite deck. Other key components include the truss suspension system at center span, abutment and pier to truss connections, and deck expansion joints. The bridge is a 2,428 foot long truss bridge that rises over 700 feet above the American River canyon. It provides the primary link between the towns of Auburn and Foresthill, California. As part of the retrofit, the bridge was also widened to maintain traffic while the retrofit measures were constructed.

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