|Project Title:||Structural Health Monitoring of Suspension Bridge Main Cables|
|Issued by:||Oregon Department of Transportation view agency website|
DescriptionThe Oregon Department of Transportation ("ODOT" or "Agency") is seeking Proposals from Professional Services consultants to provide structural health monitoring of suspension bridge main cables. Proposers responding to the RFP do so solely at their expense, and Agency is not responsible for any Proposer expenses associated with the RFP. Project Description/General Background Information: Background The St. Johns bridge is a 2,067 foot long suspension bridge carrying US30 over the Willamette River in Portland Oregon. The bridge was designed by D.B. Steinman in 1929 and constructed in 1931. The main suspension cables are composed of 19 strands of 184 wires, or 3,496 wires per cable. The wires are No. 6 galvanized with a diameter of 0.196 inches. Each of the two cables is encased in Port Orford cedar fillers which in turn are wrapped in No. 9 galvanized wrapping wire from original construction. As part of a 2002 rehabilitation project, the cable assemblies were wrapped in an elastomer protection system in order to bolster the corrosion protection of the wires. The elastomer wrapping has drain ports installed for monitoring water intrusion. In 1998 Steinman Engineers inspected 3 locations in the north cable and 1 location in the south cable, after the No. 9 wrapping wire and cedar fillers were removed for visual inspection of the strands. Minor corrosion of some strands was identified and one strand had fractured due to hydrogen assisted stress corrosion cracking. Fifty two suspender cables are attached to each main cable providing vertical support for the attached deck trusses. The suspender cables are attached to the main cable via steel casting assemblies which are clamped onto the main cables. The spacing between suspender cables is 38.5 feet along the length of the main cables. Requested Services Agency is requesting proposals for the design, installation, operation and maintenance of a structural health monitoring system ("SHM System" or "System") that can detect and locate fracture events of the wire strands which compose the main cables of the suspension portion of the bridge structure. It is anticipated that acoustic emission sensors will be installed on the vertical suspender rope castings which are clamped onto the main cables at the suspender rope locations. Disassembly of the suspender rope castings or the existing cable wrap system will not be allowed for this project. Modification of the castings such as drilling and tapping threaded holes, bolted attachments or the use of adhesives will be considered for means of attaching sensors to the castings. The SHM System is anticipated to be composed of sensors, lead wires or RF communication, data acquisition, signal conditioning, weather proof enclosures, data storage, transfer and analysis, all of which is to be provided by Consultant. System electrical power can be provided by solar panels, wind turbines, land supplied power or a combination of these sources. After the System has been installed, Consultant shall demonstrate the sensitivity of the System to simulated wire strand fracture and event location accuracy. The SHM System is anticipated to be operational for a minimum period of 2 years from the installation date, after which the results of the monitoring will be evaluated by Agency to determine if further monitoring is required up to a maximum monitoring period of 4 years. Agency prefers to rent or lease the monitoring equipment as opposed to purchasing, for the duration of this project.
ContactContact Stacie Olano at 1 (503) 986-6913
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Contact Stacie Olano at 1 (503) 986-6913
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