International Shipping Company Air Hub Mezzanine Expansion
Tinicum Township, PA
Expansion of an air hub required retro-fitting the mezzanine level within the eastern portion of the existing warehouse to match similar construction that occurred to the existing mezzanine within the western portion of the warehouse. The mezzanine is partially supported on existing columns and new columns supported on isolated pile caps and a deep foundation system.
Retro-fit construction had two main challenges: 1. To be able to construct foundations inside the active building without disruption to operations and; 2. To support 185- to 515-kip column loads with soil conditions consisting of 5 to 10 feet of sandy fill with variable amounts of clay and organics, overlying 50 to 55 feet of very loose to loose alluvial sands, underlain by 20 to 25 feet of denser alluvial sands, overlying stiff to hard residual clays.
Since the deep loose soil profile was not conducive to traditional ground improvement, the geotechnical engineers recommended a pile foundation be used to support the footings.
However, working in a warehouse with low head room for driving piles created a number of construction challenges. In addition to limiting the affects of vibrations on existing equipment and foundations, it also limited the equipment that could be used, which affected both the cost and production schedule for installation.
Dynamic Earth recommended supporting the proposed mezzanine on a Ductile Iron Pile (DIP) foundation system. DIP’s had three advantages over a normal pile driving operation:
- Uses a High Frequency Impact Hammer for installation – which reduces vibrations to very low levels.
- DIP elements come in 16.4-foot long sections with a bell and spigot connection which eliminated the need for splicing, minimized waste and provided a workable length pile for the site head room, all things that sped up construction.
- Installed with a Small Excavator – Allowed for construction with as little as 22 feet of headroom working within a small footprint at each pile cap location.
Using a design-build approach and multiple load tests performed as production progressed, the designers were able to optimize design lengths by using lower capacity, shorter length piles to support the lightly-loaded footings in the lower alluvium and the heavily-loaded footings in the lower hard residual clays.
International Shipping Company
CVMNEXT Construction - King of Prussia, PA
Architect / Structural Engineer
CVM - King of Prussia, PA
Dynamic Earth - Chester, NJ