MACHINE FOUNDATION:
Foundation provided below the superstructure of vibrating and rotating
machine for installation, is known as machine foundation. It essentially
consists of a mass of concrete. Design of machine foundation involves
consideration of static load and kinetic forces.
The load of the machine is the static load which is of minor
importance in the design of a machine foundation. The moving parts of the
machine develop inertia forces which are the major forces to be considered in
its design. The kinetic or inertia forces are periodic and vibratory in nature,
the magnitude of which depends on the type of machine. The general principles
of machine design are enumerated as follows:
1. Machine foundations should be isolated from the adjoining parts of
the building by leaving a gap around it to avoid the transmission of
vibrations. The gap is filled with suitable insulator or dampers.
2. The foundation should be stiff and rigid to avoid possibilities of
tilt in it.
3. In static state, the resultant of forces acting on machine
foundation should pass through the c.g of the contact area of the base.
4. The weight of the foundation block should be adequate. It should be
able to absorb vibrations and resist resonance between adjoining soil and the
machine. The weight of the foundation block may be assumed roughly 2.5 times
the weight of the machine.
5. A vibration absorbing medium is introduced between bottom of the
foundation block and the floor on which it is resting. This medium may be in
form of a rubber or leather gasket, layer of sawdust etc. Sometimes, springs
are used below the machine itself to prevent the development of the vibrations.
It is advised that relevant data of machine should be obtained from the
manufacturer before any design of foundation is undertaken.
TYPES OF MACHINE FOUNDATION:
The below video briefly explains about the important notes about the base plate and anchoring system of concrete. This video is prepared by referring the TEK 12-3C of NCMA, ASTM a36/A 36M, ASTM A 307, ASTM E 488 and AISC’s Steel design guide. In addition, a brief calculation of the strength / force calculation is also been explained.
Note: Since the video contains text and images, please download and see it off line for more clarity.
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Say API RP 686, provides complete information about the grouting of foundation and base plate.
Many thanks to google.com and doc88.com from where the details have been collected.
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