H-3 CHAPEL
a.
Introduction.
This design example illustrates the seismic design of a church building. The layout of the building is based on a
typical military church structure.
(1) Purpose. The purpose of this example is to illustrate the design of a representative military building in
an area of high seismicity, using the provisions of FEMA 302 as modified by this document.
(2) Scope. The scope of this example problem includes; the design of all major structural members such
as steel gravity and moment framing, reinforced concrete shear walls and horizontal steel pipe bracing. The design
of the foundations, nonstructural elements and their connections, and detail design of some structural elements such
as reinforced concrete slabs (roof and slab on grade) were not considered part of the scope of this problem and are
therefore not included (See Problem H-2 for the design of concrete floor and roof slab and Problem H-4 for the
detailed design of steel moment connections)
b.
Building Description.
(1) Function. This building functions as a Chapel with a capacity of more than 300 people.
(2) Seismic Use Group. The Seismic Use Group is determined from Table 4-1. The primary occupancy
of this structure is public assembly with a capacity greater than 300 persons. This type of occupancy places the
building in Seismic Use Group II, Special Occupancy Structures. With the Seismic Use Group known, the
Structural System Performance Objectives are obtained from Table 4-4. Structures in Seismic Use Group II are to
be designed for Performance Level 2, Safe Egress. Ground Motion A (2/3 MCE) is to be used for Performance
Objective 2A. The Minimum Analysis Procedure to be used is the Linear Elastic with R Factors and Linear Elastic
with m Factors. The structure is designed first for Performance Objective 1A following the steps laid out in Table
4-5. After completion of the preliminary design, the enhanced performance objectives outlined in Table 4-6 for
Performance Objective 2A are checked and the building design updated accordingly to meet those objectives.
(3) Configuration. The main chapel area has a high roof area (roof at ridge is 33' 3" high or 10.14m).
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There are low roof areas (10'in height or 3.05m) that run 90'(27.45m) on each side of the main open area. There
are two sacristy areas at the rear end of the building that measure 10'x 19' 8" by 10'high (3.05m x 6.00m by 3.05m
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high)
(4) Structural systems. Steel transverse moment frames support the gravity loads from the high roof area.
Metal decking spans over purlins spaced at 10'(3.05m), and the purlins span to the steel moment frames (spaced at
18'or 5.49m o.c.). In the low sloped roof areas that run parallel to the main high roof area, gravity loads are
supported by metal decking, the decking spans between the shear walls along lines A & I and the window walls
along lines B & H. The upper level concrete window/shear walls along lines B & H are supported by beams that
span in the longitudinal direction between the columns of the transverse moment frames. Gravity loads at the
sacristy areas are supported by reinforced concrete slabs (slab design not included in scope of problem).
The primary lateral force resisting elements for this structure consists of specially reinforced concrete shear walls.
In the longitudinal direction the concrete shear walls resist the entire shear force. Seismic forces from the upper roof
area are transferred from the diaphragm to the shear walls along lines B & H. These walls are supported by steel
beams at the level of the lower sloped roof diaphragms and are not continuous to the ground. Horizontal pipe
bracing transfers the shear from these walls to the exterior shear walls. In the transverse direction lateral forces are
also resisted by a combination of concrete shear walls and steel moment frames. The upper roof diaphragm is
assumed to act as a flexible diaphragm. Therefore, inertial forces are resisted by the concrete shear walls and steel
moment frames based on tributary areas. The moment frames are assumed to be braced by the horizontal bracing at
the level of the lower sloped roof areas (along wall lines B & H). The horizontally braced diaphragms of the low
sloped area are assumed to act as rigid diaphragms (the diaphragm action falls between flexible and rigid.
Analyzing the diaphragms as rigid produce was found to produce the most conservative design for the shear walls
and horizontal bracing). The sacristy roof diaphragms are composed of reinforced concrete slabs which are assumed
H3-1
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