California Department of Transportation
Today's Date: July 9, 2015
Contact: Leah Robinson-Leach
World Renowned Experts Advise Immediate Preliminary Actions on Anchor Rod Testing Plans
OAKLAND – Acting on the advice of a specially convened panel of experts, the chief engineer of the Bay Bridge will ask an oversight board today to begin taking steps toward providing long-term protection for a network of more than 400 anchor rods beneath the span’s iconic tower.
Although the recently convened panel has many weeks of work ahead of it, the internationally renowned scientists and engineers agreed that Caltrans should take certain immediate actions.
“Some of the brightest minds in marine foundation engineering and corrosion science have encouraged some preliminary actions in our ongoing investigation of the tower anchor rods,” said bridge spokeswoman Leah Robinson-Leach.
Dr. Brian Maroney, chief engineer on the bridge project, will ask the TBPOC to move forward with the following recommendations:
- Design a dehumidification system to more thoroughly dry most of the anchor rod holes below the iconic tower.
- Acquire special jacks to facilitate the cleaning of the rods as well as being immediately available for any further tests and maintenance.
- Conduct a custom steel-assessment known as the Lou Raymond Test, named after its inventor. This will help determine if micro-indications present within the specimens would have any effect on the useful life of anchor rods.
- Identify the appropriate supplemental corrosion protection system and backfill material such as grease or some other compound or synthetic material.
The anchor rods became the focus of attention when Caltrans discovered they were ineffectively grouted by the contractor and sitting in standing water. In subsequent testing, more than 99 percent withstood the most severe earthquake-level tension they are expected to experience, but two had stripped threads and one stripped to the breaking point. The oversight committee then called for the gathering of world-renown experts, many of them members of the National Academies of Science and Engineering.
The experts, including representatives of the Federal Highway Administration are being fully briefed on the history of the tower base anchor rods, and are expected to participate in a workshop later this month. During the workshop, experts will provide counsel on the present anchor rod investigations and long-term corrosion protection strategy. Following the workshop, the experts’ advice and recommendations will be taken back to the TBPOC for consideration. A formal report will follow.
The tower base anchor rods are part of a seismic system designed to ensure that during a seismic event there is no uplift during a massive quake. Caltrans is further testing to ensure the Bridge will perform for its entire 150 year design life span.
Also Thursday, a separate group of experts, the Seismic Peer Review Panel, is scheduled to take a technical field review of Yerba Buena Island with Dr. Maroney and other members of the Caltrans team, to view actual field conditions with a briefing from design and construction engineers. The Panel also is expected to attend the TBPOC meeting.
During Thursday’s TBPOC meeting, Caltrans Environmental Compliance Manager, Stefan Galvez, is expected to provide an update on the array of permits required to remove Pier E3 from the Bay waters in November 2015. And Caltrans officials will detail the volume of documentation gathered during the construction of the tower base foundation – tens of thousands of electronic files and over 150 boxes of paper reports.Please visit www.baybridgeinfo.org for more details about the Bay Bridge project.