LULING BRIDGE (HALE BOGGS MEMORIAL BRIDGE)

This bridge is a five-span cable-stayed bridge supported by twin steel towers and four concrete piers. The concrete deck overlay is supported by an orthotropic deck system integrated with transverse floor beams supported by twin longitudinal trapezoidal steel box girders. The supporting cables originate from the steel towers and are anchored at twelve transverse steel trapezoidal cross girders. Twin longitudinal trapezoidal steel box girders are supported by these cross girders, towers, and piers.

The scope of work included:

Detailed inspection of the bridge’s condition, including existing fatigue prone details, and the extent of existing cracks.
Evaluate and rate the existing bridge superstructure, including all major load-carrying components and bearing seats.
Investigate the cause of fatigue cracks using 3-D finite element analysis.
Prepare the bridge rehabilitation design.
Develop appropriate construction staging/phasing schemes and Maintenance & Protection of Traffic Plan based on TMP Level IV.
Prepare construction cost estimates and schedule.

LA-70 OVER MISSISSIPPI RIVER (SUNSHINE BRIDGE)

The Sunshine Bridge, located in Donaldsonville, LA, is a steel truss bridge opened in 1964. The bridge includes a steel deck truss and five continuous main truss spans. The main truss is a five-span cantilever structure utilizing intermittent drop spans, covering a total length of 3,327 ft. and a width of 60 ft. The approach structure consists of a variety of steel beams and girder types in addition to a deck truss span consisting of 10 panels equally spaced at 34.3 ft. The substructure of the approach spans consists of steel bents.

The project scope included performing inspection, assessment, a detailed 3-D finite element analysis and load rating of the main truss, including gusset plates, deck truss, steel approach spans and substructure elements.

I-10 OVER CALCASIEU RIVER BRIDGE (LAKE CHARLES BRIDGE)

The I-10 bridge over Calcasieu River is a steel truss cantilever bridge, opened in 1952 in Lake Charles, LA. The bridge includes a steel main truss, four steel deck trusses, and ninety approach spans. The approach spans are comprised of steel girder spans and fracture critical spans (two-girder system with floor beams and stringers). The total bridge covers an approximate length of 6,617 ft. and a width of 62.67 ft.

The major scope of work included inspecting the entire bridge, determining the affect of section losses and deficiencies on load rating, building the 3-D finite element model for the truss spans using LUSAS, rating the truss members and gusset plates, load rating the approach spans using Virtis, load rating the substructure using RC-Pier, spreadsheets, and writing the final evaluation report with repair recommendations.

ASSAWOMAN BAY BRIDGE

Assawoman Bay Bridge

The Assawoman Bay Bridge, Maryland, consists of 139 spans. Longitudinal, transverse and shear cracks were observed during past routine inspections of the prestressed concrete box beams and AASHTO girders. The first phase of the project consisted of conducting an extensive investigation to determine the cause of these cracks and their affect on the performance and durability of the bridge. The investigation consisted of performing a hands-on inspection of the bridge elements, invasive testing of selected locations, collection of core samples, and performing chloride ion content analysis along the bridge.

The results from chloride ion penetration analysis and testing indicated severe corrosion and deterioration in the main span and five box section spans. The AASHTO girder drop span was deteriorated to the extent that complete replacement of the span was necessary. Analysis of the existing damage showed significant deterioration, due to corrosion of both the box beams and the AASHTO girders, that required immediate structural repairs. The results of the investigation were presented in a report recommending replacement of the drop span and preventative maintenance such as sealing and painting concrete surfaces, epoxy injection of cracks and structural strengthening of selected AASHTO girders and box beams using carbon fiber reinforced polymers (CFRP). The construction work for the entire project was completed successfully within six months at a construction cost of approximately $1,800,000, considerably less than the $12M estimate prepared by another consultant.