Building298_Part3_Ch6_B10-Revised.pdf

Repair Building Envelope and Interior Finishes, Building 298 WO # N40085-19-F-6882 Building 298, Cherry Point, North Carolina

PART 3 - CHAPTER 6 - Page 627 07/07/2020

B10 SUPERSTRUCTURE

SYSTEM DESCRIPTION

The superstructure consists of structural elements above the foundation that provide support for vertical loads and resistance to lateral loads.

This section includes the requirements for the superstructure of the building, including floor and roof framing, columns, interior load-bearing walls and the main lateral-force resisting system. Exterior load bearing walls are addressed in Section B20.

Provide the building framing system in accordance with Unified Facilities Criteria (UFC) 3-301-01, Structural Engineering.

Importance Factors

Use Risk Category II in Table 2-2 of UFC 3- 301-01, Structural Engineering for determining Importance Factors for seismic, snow, and wind design.

Seismic Design Category

The Seismic Design Category is B.

Wind Exposure

Base wind on Exposure C.

B1010 FLOOR CONSTRUCTION

Not used.

B1020 ROOF CONSTRUCTION

The roof construction at new additions may include any structural framing system meeting the requirements of this section.

Building 298 was constructed largely in 2 phases. The original building was constructed 1942 and consisted of a central high bay auditorium with one-story office and shop areas on the plan north and east of the auditorium; and a two-story wing to the plan east of the auditorium. Roof framing for the original building consist of 14gage steel purlins spaced at 24” on centers spanning to steel trusses above the high bay auditorium area; and 14gage steel rafters spaced at 24” on centers spanning to steel beams and columns above the wing area. Roof deck consist of 2x6 timber decking.

In 1944 two-story additions were made. They consisted of a wing on the plan west of the original auditorium, and wings added to the plan north side of the east and west wings. Roof framing for the additions consist of a wood “trussed rafter” system spaced at 16” on centers spanning to an

Repair Building Envelope and Interior Finishes, Building 298 WO # N40085-19-F-6882 Building 298, Cherry Point, North Carolina

PART 3 - CHAPTER 6 - Page 628 07/07/2020 interior wood post and ridge beam and exterior wall. Roof deck consist of 2x6 timber decking.

As mentioned above the roof deck at the existing building consist of 2X timber decking. Analyze existing roof diaphragm, connections of the roof diaphragm to the roof framing members, connections of timber trussed rafters, connections of light gage rafters and roof-to-wall connections per International Existing Building Code (IEBC-15), Section 403.8. Reinforce existing roof components as required.

The condition of the roof decking and framing is in generally good condition, but may require some deteriorated boards to be replaced. Assume 25% of the roof decking will need to be replaced for bidding purposes.

Contractor to verify condition of roof framing and decking members. Decking and connections to existing framing shall be designed per IBC. Use Design Wind Speed of 139 mph for Risk Category II structures per UFC 3-301-01, Structural Engineering. Additionally, uplift connectors do not appear to be in place and will be required to be installed. Contractor to verify conditions and provide signed-and-sealed calculations for all structural analysis.

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