Abstract:
ABSTRACT
The Howard Frankland Bridge mega-project consists of a new 3.2-mile bridge along I-275 over Tampa Bay. Two steel sheet pile and Combi-Wall bulkheads with total length greater than 11, 000 linear wall feet were required to create the land for the new roadway and bridge approach. Nearly 1, 300 permanent grouted soil anchors support the bulkhead which in some cases retains a 20-foot tall MSE embankment. Anchors with lengths up to 200-feet were installed and load ranges necessitated anchors that varied from 3-stands to 8-strands. Bolted w-shape walers with a built-up thru-beam connection were used in the Combi-Wall area. Welded w-shape walers with wedge plates were used in the sheet pile area. The soil conditions at the site were typically loose to dense sands underlain by a thin layer of clay then variable hardness limestone. Given the magnitude of the design loads, the larger anchors were required to bond into limestone. Limestone variability along the bulkheads was observed. In some extreme cases, the top of the limestone elevation varied by nearly 100-feet, which creates challenging conditions when anchors are required to bond into the limestone. Given the proximity to Tampa Bay, most of the work was performed from a barge. Waler systems were installed on the waterside of the sheet piles, so installation and welding work was limited to lower tide stages. The geotechnical contractor designed and installed the anchor and walers systems to fit within the proposed concrete cap. The objective of this paper is to discuss the significant design and installation challenges of the anchor and waler system for this high-profile project.