Design Criteria for Horizontal Equipment
1. Wind
Load:
a). Basic diameter = diameter O.D. + 2 ( shell thickness +
insulation).
effective projected area = height x I.F. x basic
diameter.
b). Intensification Factor (I.F.):
Diameter ≤ 760
mm, I.F. = 1.50
Diameter 900 to 1350 mm, I.F. = 1.40
Diameter 1370
to 1960 mm, I.F. = 1.30
Diameter 1980 to 2570 mm, I.F. =
1.20
Diameter ≥ 2590 mm, I.F. = 1.18
c). The vessel saddle to
pier connection shall be considered fixed for transverse loads.
d).
Longitudinal winds shall be resisted by the fixed end pier only.
e).
The force required to remove tubes from heat exchanger shall be 100% of bundle
weight, but ≥ 19kN.
2. Load Combinations:
Empty Load
(or Erection Load) + Wind (Seismic)
Operating Load + Temperature + Live
Load
Operating Load + Wind (Seismic)
Operating Load + Temperature +
Wind (Seismic)
Operating Load + Temperature + Live Load + Wind
(Seismic)
Test Load
Test + 0.5 Wind (Seismic)
Empty Load + Bundle
Pull Load (applies to supports only)
3. Sliding
Plates:
Teflon plates are normally 25 mm smaller than the length
and width of the saddle base leaving 12.5 mm margin all around.
Vessel
support and top Teflon plate shall have horizontal slotted holes to allow
movement due to expansion and contraction.
4. Pier
Design:
Pier shall be designed as cantilever columns, k =
2.0.
Pier width ≥ 10% of height or 300 mm, minimum concrete cover for
anchor bolts shall be 100 mm.
Normally, pier dimensions = saddle
support base plate size + 100 mm.
A double tie shall be placed at top
of piers spacing 50mm and 125mm below top of concrete.
Minimum vertical
reinforcement = 0.25% times gross section area.
5. Footing
Design:
The common footing is used for pier spacing ≤ 4m.
Use
two separate spread footing when pier spacing > 4m, tie beam may be
used.
6. Normally, the stability ratio is ≥ 1.5 for sliding and
overturning.
7. Soil Bearing:
e ≤ a/6
B.P.max = P/a [1 + 6e/a] B.P.min = P/a [1 -
6e/a]
e > a/6 B.P. = 2P / [3a(a/2 - e)]
Structural Loads
Ultimate
Limit States (ULS) ----------------include exceeding the loading-carrying
capacity, overturning, sliding, and fracture.
Serviceability Limit
States (SLS) ---------include deflection, vibration, permanent deformation
and local structure damage such as cracking.
D ...... Dead load - a
permanent load dure to the weight of building components.
E ......
Earthquake load and effects - a rare load due to an earthquake.
H ...... a
permanent load due to lateral earth pressure.
L ...... Live load - a
variable load due to intended use and occupancy.
P ...... Permanent effects
caused by pre-stress.
S ...... Variable load due to snow, including ice and
associated rain.
T ...... Effects due to contraction, expansion, or
deflection caused by temperature change, shrinkage, moisture change, creep,
ground settlement, or a combination thereof.
W ...... Wind load - a
variable load due to wind.
Load Combination for U LS
Case |
Principal Loads |
Companion Loads |
1 |
1.4 D |
- |
2 |
(1.25D or 0.9D) + 1.5L |
0.5S or 0.4W |
3 |
(1.25D or 0.9D) + 1.5S |
0.5L or 0.4W |
4 |
(1.25D or 0.9D) + 1.4W |
0.5L or 0.4S |
5 |
1.0D + 1.0E |
0.5L + 0.25S |
Square Foundation Design steps (with Moment)
نوت: در صورت موجودیت مومنت عن المرکزیت (e)Eccentricity به وجود آمده و به اندازه (e) عمل قوه به سمت x و y انتقال (shift) می گردد.
Step 1:-
Calculation of loads = WT = Wc + WF = Wc + 10% Wc
Step 2:-
Calculation of Foundation Area (A) = WT/p’ p’= Bearing capacity of soil
Step 3:-
Calculation of upward pressure (p) = Wc /A
Step 4:-
Calculation of projection
a1 = (L-b)/2 + e
a2 = (L-b)/2 - e
Step 5:-
Calculation of Depth of Foundation (D)
a) B.M. consideration :
b) Punching shear consideration :
a) B.M. consideration :
(B.M)max = Resisting Moment
pL (a)2/2 = k b d2 or Q b d2
Q=0.185 * f’c *(.09) (permissible stress/Mark of concrete )
d=
D = d + cover + dia . of bars
b) Punching shear consideration:
Punching load = punching resistance
Wc – pL2 = 4 b D q (q) all = 10 kg/cm2 D = (Wc – pL2 ) / 4 b D q
Step 6:-
As = M / fy z (As)min = ρmin b d
Step 7:-
Nos. of bars:-
Number of bars = As / Area of selected bars