MEP-Technical Manual CDN 0408.qxd - Hambro

JOIST DEPTH SELECTION TABLES
7. JOIST DEPTH SELECTION TABLES
IMPERIAL
7.1 GENERAL INFORMATION
7.1.1 JOIST DEPTH SELECTION TABLES
The following load tables give the optimized depth and the
minimum depth for a specific span and a specific load
following a certain slab thickness. Values indicated present
a uniform load on all the length with a regular spacing and
a f’ c = 3000 psi. The regular spacing is 4’-1 1 /4” for D500TM (H Series), 4’-2 5 /8” for DTC (LH Series) and 4’-0” for
MD2000 ®.
The tables have been done for three types of loading with
different thickness of concrete. The three types are residential
(live load = 40 psf), office (live load = 50 psf) and
corridor or lobby (live load = 100 psf). These three types
are used in the tables as example. Any others types of
loading can be used for the Hambro design.
The tables have been created with a certain super-imposed
dead load. Even if your superimposed dead load is a little
bit different, the optimal depth and the minimum depth in
the table will be right.
7.1.2 DEFLECTION CRITERIA
For all cases presented in the tables, deflection for live load
does not exceed L / 360.
7.1.3 JOIST IDENTIFICATION
The load tables are provided to aid engineers in selecting
the most optimal depth of joist for a particular slab thickness
and a specific loading.
The engineer should specify the joist depth, slab thickness,
the design loads, dead, live and total together with special
point loads and line loads where applicable. Canam will
provide composite joists designed to specially meet these
requirements.
7.1.4 JOIST DESIGNATION
The joist designation should simply be the joist depth
followed by the total allowable service load and live load in
pounds per linear foot applied on the joist.
Example: H10-493/205 for Hambro D500
Example: LH24-493/205 for Hambro DTC
Example: MDH10-493/205 for Hambro MD2000
7.1.5 EXAMPLE
Find the optimal depth and the minimum depth for the
following office project with Hambro D500 (H Series).
Span: 32’-0”
Slab thickness: 4”
Joist spacing: 4’-1 1 /4”
Concrete strength: 3 000 psi
Yield point of steel: 55 ksi
Concrete density: 145 lb./ft. 3
Dead load: 77 psf
Joist: 2.5 psf
Concrete: 48.5 psf
Mechanical: 3.0 psf
Ceiling (1/2”): 3.0 psf
Partition: 20 psf
TOTAL: = 77 psf
Live load
According to NBC: 50 psf
Solution:
From tables, find slab thickness = 4” with a span = 32’-0”
In the table, with dead load = 77 psf and live load = 50 psf,
we find:
Optimal depth = H20
Minimum depth = H14
Then:
H20 means depth = 20”
H14 means depth = 14”
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