WHAT HAVE BEEN ACCOMPLISHED:
JMEC has been Prime Design Consultant for various roadway and bridge projects for the USDA Forest Service. Work performed including field visits, inspection services, structural design, civil and roadway design, geotechnical investigation, lead based paint testing, design reports, preparation of construction documents and construction cost estimating.
The Circle Bridge is a 498-ft riveted steel deck truss supported on steel towers. It has a maximum span of 173-ft and a deck width of 30-ft. The bridge crosses the North Fork of the Middle Fork of the American River.
JMEC performed seismic evaluation and retrofit design based on deterministic and probabilistic approaches together with ATC-32 seismic design criteria. Hydraulic evaluation was performed to evaluate impacts of the retrofits on stream flow. The existing structure lacks the uplifting and overturning capacity, and has insufficient capacity at the superstructure to tower connections and at various bracing locations. However, due to difficult site access of heavy equipment and the existing rip-rap slope, the retrofit was confined to small equipment, and made use drill-and-bond dowels into existing bedrock for foundation strengthening. Removal of existing lead paint for connection strengthening was limited to minimize the required environmental mitigation. The retrofit measures included:
JMEC has been Prime Design Consultant for various roadway and bridge projects for the USDA Forest Service. Work performed including field visits, inspection services, structural design, civil and roadway design, geotechnical investigation, lead based paint testing, design reports, preparation of construction documents and construction cost estimating.
The Circle Bridge is a 498-ft riveted steel deck truss supported on steel towers. It has a maximum span of 173-ft and a deck width of 30-ft. The bridge crosses the North Fork of the Middle Fork of the American River.
JMEC performed seismic evaluation and retrofit design based on deterministic and probabilistic approaches together with ATC-32 seismic design criteria. Hydraulic evaluation was performed to evaluate impacts of the retrofits on stream flow. The existing structure lacks the uplifting and overturning capacity, and has insufficient capacity at the superstructure to tower connections and at various bracing locations. However, due to difficult site access of heavy equipment and the existing rip-rap slope, the retrofit was confined to small equipment, and made use drill-and-bond dowels into existing bedrock for foundation strengthening. Removal of existing lead paint for connection strengthening was limited to minimize the required environmental mitigation. The retrofit measures included:
- Add drill-and-bond dowels into bedrock and enlarge footings
- Add grade beams to connect isolated footings
- Add cable restrainers across expansion joints
- Add catcher blocks and shear keys at abutments
- Strengthen tower to foundation connections
- Strengthen tower to steel truss connections
- Construct bent cap strengthening for concrete pier and add steel column casings
- Strengthen connections selectively at cross frames and bottom lateral bracing by replacing rivets with high strength bolts
Project Role: Prime Design Consultant
Clients: USDA Forest Service
Clients: USDA Forest Service
Special Issues: The design capacity of the drill-and bond dowels into rock was determined through on-site pull-out tests. A testing program was included to proof test these drill-and-bond dowels to 150% of the design values during construction.
Schedule: Construction was completed in 2004 with a final cost within 2% of contractor's bid. JMEC has helped the Forest Service to complete this 15 years old project.
Schedule: Construction was completed in 2004 with a final cost within 2% of contractor's bid. JMEC has helped the Forest Service to complete this 15 years old project.
Overview of Circle Bridge
Bent Cap Retrofit with Column Casing and Cable restrainers
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165 Lennon Lane, Suite 106, Walnut Creek, CA 94598
Tel: (925) 944-8999 Fax: (925) 944-9998
165 Lennon Lane, Suite 106, Walnut Creek, CA 94598
Tel: (925) 944-8999 Fax: (925) 944-9998
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