Page 104 - Machinery Component Maintenance

Machinery Foundations and Grouting 87

Solution A Solution B Solution C
Bolt with attached Keying the corners Changing dimensions
washer cemented in with epoxy grout of shoulder to
with unfilled epoxy to transfer stress x less than y
grout when x is to shear area
greater than y to transfer
stress away from corner
Figure 3-6. Designs to eliminate stress risers in foundation corners.

tendency for cracking is greatly reduced due to the inflexibility of this
configuration. While cracking of this nature does not cause immediate
operating problems, it does provide a path for oil to penetrate into the
foundation. Over an extended period of time support will be diminished
as oil degradation of the concrete proceeds.
Cracks of this nature can be virtually eliminated by utilizing one of the
design techniques illustrated in Figure 3-6. Solution A is based on the
transfer of stress away from the corner. This technique also changes the
stress from tension to shear. Solution B transfers the stress away from the
corner to a shear area on the back side of the key. Solution C changes the
usual cross section dimensions of the shoulder, making a relatively in-
flexible configuration. Other designs, such as feather edging the grout,
can be used, but all are based on eliminating stress risers at the founda-
tion corners.

Expansion Joints

The small differences in thermal expansion rates between concrete or
steel and an aggregate-filled epoxy grout become increasingly important
as the length of the grouted equipment increases. Cracking can be ex-
pected near regions of anchor bolts or at rail or sole plate ends, unless
care is taken in the design to eliminate stress risers. This is particularly
true during equipment startup or shutdown where a temperature gradient
might be created or when brittle grouting materials are employed. For
example, during startup of rail-mounted equipment, the rails begin to