15 September 1999
EXAMPLE PROBLEM C3
INFILLED STEEL FRAME BUILDING
C3-1. Building Description
The French Theater (Building 2004) is a one-story infilled steel frame building located at Fort
Lewis, Washington. The steel frames are infilled with unreinforced hollow clay tile walls.
According to the available drawings and information, the building was originally built in 1932. It
was apparently enlarged in 1940. The drawings reviewed were prepared for the 1940
modification, and generally represent the existing condition of the original building, but do not
provide the detailing and reinforcing information of the original building.
The original building had overall plan dimensions of approximately 48 by 120 feet, with the main
theater section measuring 48 by 100 feet. The modified building has overall plan dimensions of
approximately 80 by 132 feet, consisting of the 80-foot by 100-foot main theater section, and 30-
foot by 52-foot entrance and lobby area. See Figure C3-1 for plans, and Figure C3-2 for
a. Vertical-Load-Resisting System. The ground floor is a concrete slab poured on
excavated ground to form a sloped surface (reinforcing is unknown). The roof consists of
Spanish tile on 2-inch by 6-inch roofing plank supported by a steel joist and truss system. Steel
columns support the truss. The steel columns along the exterior are infilled with the hollow clay
tile walls. The footings consist of individual spread footings for the columns and strip footings
along the perimeter of the structures.
b. Lateral-Load-Resisting System. The primary lateral-force-resisting system consists
of horizontal wood sheathing connected to the top flange of the upper chord of the trusses
through 3-inch by 6-inch nailer and steel joists. The unreinforced masonry shear walls along the
exterior resist the lateral load. The lateral load is transmitted to the walls through the roof
diaphragm, with contribution from intermediate collectors and steel framing and X-bracing
consisting of angles and rods.
c. The 1940 Modifications. During the 1940 modifications, the auditorium portion was
widened and the entrance area was enlarged. The auditorium portion was widened from 49
feet, 4 inches to 80 feet, 4 inches, and the entrance area was enlarged from 39 feet by 20 feet,
2 inches to 52 feet, 8 inches by 30 feet, 8 inches. The transverse framing consists of end shear
walls and four interior truss-column frame systems. During the 1940 modifications, the columns
of the two interior trusses were removed and a carrying truss was installed to transfer the
vertical load to the adjacent columns.
C3-2. Building Review Report
a. Seismic Review of Structural Systems. The review procedure described in Chapter 2
was performed for Building 2004 using the Lateral Load System Data Sheet and Structural
Review Score Sheet. The review was performed only on the auditorium section of the building
because it appeared to pose the most severe condition.