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ACI
WEB SESSIONS
Analysis and Design Issues inLiquid-Containing Concrete
Structures
ACI Fall 2012 ConventionOctober 21 24, Toronto, ON
ACI
WEB SESSIONS
Steven R. Close has 40 years experience designing both
post-tensioned and conventionally reinforced watercontainment and
treatment structures of all shapes and sizes.His designs are
located all over the US, Canada, theCaribbean, as well as Asia, and
the Middle East. He was a
long-time Principle of Jorgensen & Close Associates, andnow
is with minority-owned WHPacific.
Steven R. Close, PE
Toronto, Fall 2012 ACI Convention
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Its been a part of 350 documents since the mid
1990s (350.2R-95 Hazardous Materials)
Has not been introduced because of the rules
For developing the original C&C 350-01Must reflect
350R-89
And the first revision, 350-06No new business catch up to 318
only
350 C (Reinforcement) has been working onthis since before
2006
Balloted by Main Committee in 2009
Field ObservationsVertical wall cracks much closer than the
presentlyindicated distances between movement dissipating
joints (30, 40 and 50 ft)
Field Observations
Cracks in checkerboard placed SOGs
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Field ObservationsCorner cracks in suspended slabs
Field ObservationsCracks ending at construction joints
Field ObservationsNo cracks in walls to be prestressed,
even after months until application ofhorizontal or
circumferentialprestressing
Research
Dr. Reza Kianoush
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L=6 m
L=9 m
L=12 m
L=18 m
L=24 m
L=30 m
L=60 m
Shrinkage Cracks cant be preventedin all cases, but they may be
able to becontrolled to where we have a largernumber of cracks
small enough to notseep (0.1mm).
Tie reinforcement levels to amount ofrestraint
Not distances between movement joints (except 20 ft and
under).
Reduced RestraintFor vertical wall reinforcement
(except near Construction Joints)Where measures are taken to
reducerestraint of shrinkage andtemperature shortening
Maximum RestraintWhere shrinkage and temperatureshortening is
prevented by ties topreviously placed concrete
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Normal RestraintAnywhere not defined as Reducedor Maximum
Restraint
Slabs on soil away from construction jointsHorizontal
reinforcement in walls,away from bottom construction joints
Similar to the prior amounts,depending
Normal RestraintDesigned around 0.42%
#5s at 12 inches o.c. each face in a 12-in. section15mm bars at
300mm o.c. each facein a 300mm section
Maximum RestraintDouble the Normal Restraint values
Reduced restraintStarting at 0.28%
#4s at 12 inches o.c. in a 4-inch slab13mm bars at 300mm o.c. in
a100mm slab
Varies with Bar SizeSmaller bars closer together controlcrack
widths better than the samepercentage with bigger bars
fartherapart
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