A three-cylinder vertical compressor weighing 10 tonnes is driven
with an electric
motor weighing 1.5 tonnes. The operational speed of the compressor
is 600 cpm. The
exciting forces generated by the cylinders are
PzR (Right-Cylinder)= 5.0×sin(2πt×10)
PzM (Mid-Cylinder)= 7.0×sin(2πt×10)
P
zL (Left-Cylinder)
= 5.0×sin(2πt×10)
in tonnes in vertical direction. The distance between the cylinders
is 1.2 m (See
Figure 2). The limit vibration amplitude of 0.3 mm has been
specified by the
manufacturer for the machine. The vibrations must not be annoying
to the persons
working in the factory. The piles and the soil have the following
properties:
Piles:
Consider the piles and pile-cap made of concrete,
Unit weight of the concrete: 23 kN/m3,
Young modulus E
P = 21×106 kPa,
Poisson’s ratio = 0.35.
Minimum depth for the rigid pile cap: 60 cm.
Minimum equivalent diameter of piles: 20 cm.
Soil:
Unit weight of the soil = 20 kN/m3
Young modulus of the soil Es: The last 5 numbers of zID + 20,000
(kPa),
Poisson’s ratio= 0.25.
1) Design a 2×2 floating pile-group foundation for the
compressor.
In this assessment, you are required to determine the proper
dimensions of piles and
pile-cap, pile spacing ratio (s/d), total dynamic stiffness of the
foundation, natural
frequency of the system, and the amplitude of the vibration. At the
end of the
calculations, draw the plan and elevations of the foundation to
show all the
dimensions (Also show the location of the machine in the
figures).
Notes:
- In design, try to reduce the weight of the foundation (not
necessarily an
absolute minimum) with an appropriate and constructable
geometric.
- You may assume any material parameters (data) that you think are
required for
the design but have not been specified in the question.
2) If the mid-cylinder moves out-of-phase by 90°, i.e.
PzR (Right-Cylinder)= 5.0×sin(2πt×10)
PzM (Mid-Cylinder)= 7.0×sin(2πt×10+ π/2)
PzL (Left-Cylinder)= 5.0×sin(2πt×10),
briefly describe how the effect of this phase difference can be
taken into account.
(Note: You do not need to redesign the foundation for this case.)
- Design Of A Machine Foundation On Piles A Three Cylinder Vertical Compressor Weighing 10 Tonnes Is Driven With An Elec 1 (28.28 KiB) Viewed 48 times