MEP-Technical Manual CDN 0408.qxd - Hambro

DESIGN PRINCIPLES AND CALCULATIONS
4.8.2 MD2000 ® SERIES
The standard Hambro MD2000 section, being 95 mm
(3 3 /4”) deep, possesses sufficient flexural strength to become
the major steel component of the mini-joist series. The two
sizes that are currently being used are illustrated in the figure
below and spans beyond 2 400 mm (8’) can be achieved with
the heavier RMD unit. Other sizes are also available.
The composite capacities of the MD & RMD units are calculated
on the basis of “elastic tee beam analysis”. The
effective flange width, b, equals the lesser of span/4 or
joist spacing. With the mini-joist spaced at 1 251 mm
(4’-1 1 /4”), b is dictated by span/4. The load table lists
total unfactored load capacity in kN/m (plf) for span up to
2.64 m (8’-8”).
L 1 5 /8” x 2” x 0.09”
LLH
MD
3 /4” φ rod x 3” length
at each end
TABLE 12: Mini-joist MD2000 Series Span Chart
TABLE 13: Mini-joist MD2000 Series Span Chart
Fig. 19
Full scale tests have demonstrated consistently that shoe
plates are not required - the section is simply notched
at each bearing end with the lower horizontal portion of the
becoming the actual bearing surface. Note that where
the non-composite end reaction exceeds 4.5 kN (1.0 kip)
the notched ends are reinforced with a 12.7 mm ( 1 /2”)
diameter bar 200 mm (8”) long.
This is to prevent the section from “straightening out”
at the bearing ends. It is interesting to note that this is not
a problem during the composite service stage, even with
its higher total loads, as the 70 mm (2 3 /4”) nominal slab
carries the vertical shears.
1 /2” φ rod
L 1 5 /8” x 2” x 0.09”
LLH
RMD
3 /4” φ rod x 3” length
at each end
and
at each 24” c/c
TYPE CONDITIONS PROPERTIES MAXIMUM CLEAR SPAN (m)
I
mm
S
4 x 106 mm3 x 103 t= 70mm
DL = 3.2 Kpa
LL = 1.9 Kpa
t=70mm
DL = 3.2 Kpa
LL = 4.8 Kpa
t=85mm
DL = 3.55 Kpa
LL = 1.9 Kpa
t=85mm
DL = 3.55 Kpa
LL = 4.8 Kpa
MD COMPOSITE 1.186 15.16
NON-COMP. 0.298 7.25 1.65 1.47 1.57 1.42
RMD COMPOSITE 1.775 24.32
NON-COMP. 0.582 13.94 2.40 2.11 2.26 2.06
t = Thickness above steel deck
TYPE CONDITIONS PROPERTIES MAXIMUM CLEAR SPAN (ft.)
I
in.
S
4 in. 3
t= 2
MD COMPOSITE 2.85 0.92
NON-COMP. 0.71 0.44 5’-5” 4’-10” 5’-2” 4’-8”
3/4” t = 2 3/4” t = 3 1/4” t = 3 1/4”
DL = 67 psf
LL = 40 psf
DL = 67 psf
LL = 100 psf
DL = 74 psf
LL = 40 psf
DL = 74 psf
LL = 100 psf
RMD COMPOSITE 4.28 1.49
NON-COMP. 1.40 0.85 7’-10” 6’-11” 7’-5” 6’-9”
t = Thickness above steel deck
19