The signature bridge in the I-395 Project consists of 6 precast segmental concrete arches, with spans ranging from about 300’ to 650’ and heights from 180’ to 330’. CHI performed analysis and final design for Arch 5, the longest and tallest arch, and the cast-in-place Center Pier, where all six arches merge. The structures are especially unique and numerous challenges had to be overcome during the design. In addition, many innovative design methods and solutions were developed.

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The designs need to account for not only numerous construction stages, but also two operational stages: when only the west-bound roadway is open to traffic and when both the west- and east-bound roadways are open to traffic. Detailed erection analysis was performed to determine the stiffness and quantities of erection towers, guy ropes and erection PT tendons.

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3D BIM/Revit models were created for the center pier where the 200+ PT tendons came together to check for clashes and conflicts. In addition, 3D rebar modeling was performed for critical locations to verify spacing and assist in rebar detailing.

 

Advanced 3D finite element models were created for the Center Pier, in which the concrete was modeled using solid elements and all the PT tendons were explicitly modeled. To calculate rebar quantities based on the 3D FE analysis, CHI developed an in-house program, following relevant ACI guidelines and other references. This program played crucial role in designing the CIP Center Pier.