Hybrid Concrete-Steel Piles and Precast Concrete Deck Expedite Construction of Bulk Handling Wharf

Abstract: As part of a very ambitious expansion program, the Port of Barranquilla (Colombia) embarked on the development of a pile-supported multipurpose marginal wharf for SubPanamax bulk carriers in their main river terminal.
The geotechnical investigation program, however, revealed the presence of a competent marl/coral stratum at highly variable elevations. The erratic nature of this stratum led to the development of a hybrid piling solution consisting of prestressed concrete pile segments lengthened via the welding of a tubular steel stinger at their tips. The concrete body of the pile needs to be prestressed to be able to resist the high stresses induced by hard driving. Its length was limited to 70 ft (21 m) due to local precasting / transportation constraints. To adjust the pile length depending on the expected competent soil elevation, a steel tubular stinger was welded to the end of the prestressed concrete pile segment. The length of the stingers varied across the site. The weld is full penetration and called for detailed inspection. The piles were high capacity, verified through extensive dynamic testing at each pile location.
The project also involved a massive use of all sorts of precast concrete elements (rectangular beams, U-beams, deck panels, cut off wall panels) for the deck construction. The formwork for the installation of the precast deck elements was supported on friction collars mounted on the cut off concrete piles. The implementation of precast concrete components for the deck also expedited the wharf construction process.
The paper describes the details of the fabrication and installation of the hybrid piles as well as the characteristics, design features and connection details of the different precast concrete elements that comprise the deck. The combined hybrid pile and precast concrete deck solution lends itself to a very fast construction process.

How does this project / topic contribute to the advancement of the industry and profession?: The implementation of hybrid piles consisting of a prestressed concrete segment with a welded steel tubular stinger allowed not only the adequate installation of piles in a difficult site with a very erratic competent soil stratum but also the development of high capacities in all piles. The welding of the stinger is a practical solution to lengthen prestressed concrete piles. This pile type is known in the industry but proper fabrication is challenging. The project also saw massive use of precast concrete elements (beams, deck panels, cut off wall panels) for the deck construction. This also expedited the wharf construction.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: Definitely. In fact, these are the first hybrid concrete-steel piles installed in Colombia. The length of the prestressed concrete pile segment was constrained by local fabrication/transportation issues. Welding of the tubular stinger provides a practical solution to lengthen the pile as needed.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: The most challenging aspect of the project was the erratic nature of the competent soil stratum (marl/coral formation). The elevation of this soil layer was highly variable along the footprint of the wharf. Regardless of the geotechnical borehole data that was obtained, the determination of pile lengths was difficult. The ability to weld steel tubular stingers of variable length to the prestressed concrete segments on site enable the Contractor to adjust pile lengths along the wharf as needed. Adequacy of pile lengths was verified through extensive dynamic testing of the piles confirming the benefits of the solution.

Who is the target audience for this paper?: The paper's target audience involves Designers, Contractors, Precasters, Owners, and Operators of Marine Terminals in general, particularly for sites where the elevation of the competent soil strata varies.