Soil-Structure Interaction Seminar - Foundation Performance ...

and rigidity to control, dissipate and distribute the actual loads.
In this way, it should control movements in the upper structure
such that a home does not have a significant number of reoccurring
problems such as sticking doors, sheetrock cracks, brick cracks,
etc. and it should not move in such a manner that the structure
itself becomes unsafe.
REQUIREMENTS:
For a proper design to be successful several items must be
'considered:
A. Good soils information is important. A proper soil study
and report, which include PTI design parameters,
allowable soil bearing values, and plasticity indiGeS, is
, recommended.
B. _Proper lot preparation and building pad placement are
necessary.
C. Proper foundation makeup and reinforcement placement must
be done.
D. Good quality concrete and proper placement of the
concrete are performance related items, which must be
controlled.
E. Correct curing procedures are important.
F. Proper grading and drainage around the home are a must111
G. Proper homeowner maintenance is also required.
It has been our experience that good construction procedures
and proper drainage have the largest overall effect on long term
performance of residential foundations.
AREAS FOR IMPROVEMENT
Areas we see which consistently can use improvement are lot
and pad preparation, curing procedures and homeowner maintenance.
A. If a lot or pad is improperly placed, initial deflection
and settlement can occur which can crack the foundation
system, which is unreinforced for a minimum of 4 days
after placement. Tendon stressing cannot be done until
the concrete strength has increased sufficiently to
accept the stressing forces. Once a crack has formed in
the foundation, the slab will "in effect" hinge at that
location and it is considerably less rigid than at the
adjacent areas of the remaining foundation system. If
the foundation is subjected to some amount of movement,
problems in the upper structure can be concentrated in
the vicinity of the crack.
Page 3