Civil Engineering Reference
In-Depth Information
time of 50 hours: 10 hours each for survey and cleaning, 20 hours for clamp
installation and bolting, 5 hours for grouting and 5 hours for inspection.
It is important to note that curing time should be included to ensure that the
unstressed grouted clamp/sleeve connection is not subjected to loading before
the grout has gained sufficient strength. In some instances, temporary clamps
may be necessary.
Several applications of unstressed grouted clamps and sleeve connections
are evident. Pile or sleeve connections for numerous jackets make use of this
technique. For repair/strengthening, unstressed grouted clamps/sleeve connec-
tions have often been used to overcome fatigue cracks and members damaged
by boat impact.
The advantages of this technique are its reasonable transfer capacity, its
good tolerance for fit-up and its ideal potential for clamping on joints and mem-
bers. It is particularly good for strengthening dented members.
The disadvantages of the technique are that, without the use of shear keys,
the required connection length may be unacceptably long and that the grout
seal, if improperly fitted, often results in leakage of grout, resulting in loss of
friction.
The equipment required for diver installation of an unstressed grouted con-
nection or clamp is:
Diving spread and divers
●
Crane for lifting and placing in position
●
Rigging for installation
●
Underwater cutting and grinding equipment, if obstructions have to be
removed
●
Bolt torque/tension equipment for spilt-sleeve clamp
●
Grouting spread
●
Monitoring equipment (e.g., video/camera)
●
Equipment to remove marine growth and grit blast.
●
Stressed Grouted Clamps
A stressed grouted clamp is formed when two or more segments of strengthened
saddle plates are stressed by means of long stud-bolts onto a tubular member
after grout has been injected and allowed to cure in the annular space between
the clamp and the tubular member.
This type of clamp is a hybrid between a stressed mechanical clamp and an
unstressed grouted clamp. The strength of the clamp is obtained from a combi-
nation of
“
”
bond and grout/steel friction developed because of the
compressive force applied normal to the grout/tubular surface interface by the
stud-bolt tension.
Stressed grouted clamps offer the benefits of stressed mechanical clamps of
high strength-to-length ratio, and the benefits of unstressed grouted clamps in
the ability to absorb significant tolerances.
plane pipe
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