MEP-Technical Manual CDN 0408.qxd - Hambro

JOIST DEPTH SELECTION TABLES
6. JOIST DEPTH SELECTION TABLES
METRIC
6.1 GENERAL INFORMATION
6.1.1 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 = 20 MPa. The regular spacing is 1 251 mm for
D500TM (H Series), 1 285 mm for DTC (LH Series) and
1 220 mm for MD2000 ®.
The tables have been done for three types of loading with
different thickness of concrete. The three types are residential
(live load = 1.92 kPa), office (live load = 2.4 kPa)
and corridor or lobby (live load = 4.8 kPa). 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.
6.1.2 DEFLECTION CRITERIA
For all cases presented in the tables, deflection for live load
does not exceed L / 360.
6.1.3 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 specifically meet
these requirements.
6.1.4 JOIST DESIGNATION
The joist designation should simply be the joist depth
followed by the total allowable service load and live load in
kN per meter applied on the joist.
Example: H250-7/3 for Hambro D500
Example: LH600-7/3 for Hambro DTC
Example: MDH300-7/3 for Hambro MD2000
6.1.5 EXAMPLE
Find the optimal depth and the minimum depth for the
following office project with Hambro D500 (H Series).
Span: 9 750 mm
Slab thickness: 100 mm
Joist spacing: 1 251 mm
Concrete strength: 20 MPa
Yield point of steel: 380 MPa
Concrete density: 2 400 kg/m3 Dead load: 3.65 kN/m2 Joist: 0.12 kN/m2 Concrete: 2.32 kN/m2 Mechanical: 0.10 kN/m2 Ceiling (13 mm): 0.14 kN/m2 Partition: 0.96 kN/m2 TOTAL: 3.65 kN/m2 Live load (According to NBC): 2.40 kN/m2 Solution:
From tables, find slab thickness = 100 mm with
a span = 9 750 mm
In the table, with dead load = 3.65 kN/m2 and
live load = 2.40 kN/m2 , we find:
Optimal depth = H500
Minimum depth = H350
Then:
H500 means depth = 500 mm
H350 means depth = 350 mm
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