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 steel may also allow the structural designer to optimize the structural frame by avoiding various
architectural constraints.
Should an exposed steel system be selected, the designers are directed to review the AISC "Code
of Standard Practice for Steel Buildings and Bridges" section 10, Architecturally Exposed
Structural Steel. It is important to note the contract documents must specifically identify the
steel which is part of an AESS system in order to ensure that the relevant AISC provisions are a
binding part of an construction contract.
The proper selection of finish and coating systems for exposed steel are extremely important to
control the long term costs associated with maintenance of the facility. High quality exterior
paint systems are typically a system of multiple layers of primers and top coats applied in phases
in the shop and in the field. Newer urethane based systems are available on the market with
reduced coatings and much simpler application requirements but, at this time, the Navy has
limited experience
with their long term performance.
The designer is advised to review the Unified Facilities Guide Specifications, section 09971
"EXTERIOR COATING OF STEEL STRUCTURES." This specification is not directly
applicable to the AESS found in hangar facilities and should be edited appropriately. Primarily,
maximum advantage should be taken of the opportunity to shop paint completed fabrications.
Secondly, a properly trained coatings inspector should be retained to oversee both shop and field
painting activities.
Strength and Serviceability Requirements
Design the overall structural system for wind uplift conditions peculiar to the site. Provide a
bridge crane in the OH space of each maintenance hangar module supporting helicopters,
propeller driven aircraft, or the C-9, V-22, or AV-8 aircraft. In the future, H-53 will normally be
housed in a type II hangar. If NAVAIR headquarters makes special exception for housing an H-
53 in a special modified type I hangar, the minimum hook clearance must be 8.2 meters (27 feet).
Do not use bridge cranes in maintenance hangars supporting other types of aircraft except in
specialized instances approved by NAVFACENGCOM or when specifically required by the
FRD. Requirements for the bridge crane, motor, and controls are given in par. 2.9. In all cases,
the hangar roof support structure should be designed to accommodate the loading from overhead
bridge crane described in par. 2.9.1.
Gravity Loads
Gravity loads on the main structural frame should be determined from American Society of Civil
Engineers (ASCE) 7, Minimum Design Loads for Buildings and Other Structures, supplemented
by actual physical data of known equipment and materials where appropriate. In determining
design load combinations for structures in which the dead load of one portion of the building
serves as stability enhancing function for another portion of the building (i.e. cantilevered
construction), the following cases should be considered in addition to the basic load cases
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