Cooper B-Line Seismic Restraints - Dixie Construction Products

Example Two, Shallow Embedded Anchors:
In this example a cable tray system is suspended on the 1st floor of a 40-foot tall, 2-story surgical
center in California. The cable tray is actually suspended from the 2nd floor, which has an elevation
of 20 feet above grade. Location of the surgical center is in seismic zone 4 with a rock soil
profile, however shallow embedment anchors (length-to-diameter ratio of less than 8) are used at
brace locations.
F p = a pC a I p
(1 + 3 hx • )W p
R p h r
a p = 1.0 from Table 16-O
C a = (.40Na) which is combination of seismic zone factor and soil profile type
from (Table 16-Q)
Where,
Z = .40 for seismic zone 4 applications (Table 16-I)
Soil Profile type = S B for rock sediment (Table 16-J)
Seismic Source Type = B for faults other than Type A & C (Table 16-U)
Near Source Factor = 1.0 for 5 km from known seismic source (Table 16-S)
I p
= (1.5) for an essential surgery and emergency treatment areas (Table 16-K)
R p = (1.5) for cable trays supported with shallow embedded anchors (Table 16-O)
h x
h r
= 20 feet, for the elevation of the floor used to support the cable tray
= 40 feet. for the elevation of the structure roof
F p = (1.0)((0.40(1.0))(1.5) (1 + 3 • 20 )W p = 1.0W p = 1.0g
1.5 40
Check if value falls within limits:
F p shall not be taken less than, 0.7C a I p W p = 0.7(.40)(1.5)W p = .42g
F p shall not be greater than, 4.0C a I p W p = 4.0(.40)(1.5)W p = 2.4g
2.4g > 1.0g > 0.42g Therefore allowing the use of 1.0g
To convert this F p from a strength design, as just determined from the building code, to an
Allowable Stress Design (ASD) used in the Cooper B-Line Seismic Restraints Manual divide by 1.4.
F p = 1.0g = 0.71g (ASD)
1.4
0.71g is the Allowable Stress Design Seismic Load Factor determined from 1997 Uniform
Building Code for shallow embedment anchors.
COOPER B-Line
509 West Monroe Street
Highland, Illinois 62249
Phone: 800-851-7415
Fax: 618-654-1917
Date:
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Raafat S. Aboulhosn
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