Page 133 - Pressure Vessel Design Manual

Design of Vessel Supports 113

Design Procedure Calculate:

Step I: Give or determine the following:
Z = 0.6h

Structure category
Exposure category
Wind velocity, V
Effective diameter, D
Shape factor, Ct.
Importance factor, I
Damping coefficient, /3
Fundamental frequency, 1
Q2 = + h 0.63 =
1 + 0.63(,>
Step 2: Calculate 1dD ratio:
Step 3: Determine if vessel is rigid or flexible.
a. If h/D < 4, T < 1 sec, or f > 1 Hz, then vessel is Vref = 1.467V =
considered rigid and:
F = qZCCfAf

11. If h/D > 4, T z 1 see, or f < 1 Hz, then vessel is
considered flexible and:

Step 4: Calculate shear and moments at each elevation by
multiplying force, F, and elevation, h,, the distance to the
center of the projected area.
Step 5: Sum the forces and moments at each elevation down
to the base.

Determination of Gust Factor, Gf, for Vessels
Where h/D > 4 orT > 1 Second
Rn = 7.465Ni -
(1 + 10.302Ni)s'3 -

Given: D,, = (effective diameter)
h= (overall height)
17 = (basic wind speed)
B= (structural damping
coefficient)
f = (fundamental natural
frequency)
g= 3.5

Determine the following values from Table 3-3:

(y =- I =
b =- E = Gf = 1 + 2gI,@TP

c, = - Zmin = 1 + 71,