Developer/OwnerDept. of Transportation, State of Hawaii
ArchitectDemattei Wong Architecture
ContractorHawaiian Dredging Construction Company
LocationKahului, Maui, Hawaii
This project is a four-level, 1.85 million SF ConRAC facility that consolidates more than 12 car rental companies into one new structure at Kahului Airport on the island of Maui. This facility designed for high seismic code requirements houses rental car counters and administrative offices; a Ready/Return structure for rental car pick up and return and overflow parking; a Quick Turnaround Area for refueling, light maintenance, and washing of vehicles, and a Tram System to connect the ConRAC Facility to the airport terminal. The Tram System includes vehicles, a 6,000 SF maintenance facility, stations, canopies and boarding platforms, guideway, and all associated equipment and facilities.
BASE value engineered the structural design including decreasing slab thicknesses, providing uniformity of the beam sizing and detailing, and simplifying detailing where possible. Our value engineering also included redesign of the foundation system from precast concrete piles to augered cast-in-place piles. Working closely with the general contractor, the code-compliant value engineering alternate design yielded significant savings in formwork costs while decreasing rebar and post-tensioned reinforcement quantities and concrete volume. Rebar weight was reduced by 20%, post-tensioned reinforcement by nearly 10%, and concrete volume was reduced by 8%. The cost savings to be shared by the State of Hawaii and HDCC were so significant that BASE was asked to completely redesign the facility as Engineer of Record.
The Science and Design of Structural Engineering
BASE was brought in by the general contractor, Hawaiian Dredging Construction Company, to conduct a value engineering review of the project. The review studies needed to take into account the complexity of high seismic design and detailing for a unique system of long-span post-tensioned special (seismic) reinforced concrete moment frames. While post-tensioning is often used for long-span concrete beam gravity designs, its use as seismic resisting frames is relatively rare. In seismic frames, the building code prohibits using more than 25% of the post-tensioning strength capacity during a seismic event. BASE ran multiple scenarios, which included adjusting the tendon control points and using harped tendon profiles, to determine the most efficient use of the post-tensioning while fine-tuning its contribution to the overall strength of the lateral system to help optimize the amount of column reinforcing that was required to satisfy the strong column/weak beam requirement.