CEMP-E
TI 809-02
1 September 1999
Where steel columns are embedded in the walls, provide joints in the plane of the
columns.
If the columns are more than 8 meters (25 feet) apart, provide intermediate joints.
Numerous ways have been developed for forming control joints in walls. Whatever method is
used, the thickness of the wall section at the joint should be reduced at least 20% by the depth
of the joint; and the sum of the depths of the inside and outside grooves should not be less
than 50 mm (2 inches).
(c) Construction Joints. Construction joints are used to allow concrete placement of
separate construction elements at different times, e.g., between columns and beams, footings
and pedestals, etc. Construction joints will be made with tie bars, dowels, or keys to provide
shear transfer. The location and details of critical construction joints will be shown on the
drawings and, to the extent practicable, will coincide with the location of expansion or control
joints. The location of other construction joints need not be shown. Cautionary and advisory
notes regarding acceptable joint locations will be included on the drawings.
(d) Seismic Joints. Buildings that are irregular in plan such as T, L, U, or cruciform
shaped buildings can generate high torsional or twisting effects when subjected to earthquake
ground motions. These structures would require a three-dimensional analysis for a rigorous
determination of stress distribution. Since such analyses are generally not practical, seismic
joints are provided to separate various blocks of the structure into regular shaped units that will
not exhibit a torsional response. The joints should be of sufficient width to prevent hammering
on adjacent blocks during earthquakes, and should be adequately sealed to protect the
structure from the environment.
(e) Sealing joints. Exterior expansion, control, and construction joints should be sealed
against moisture penetration using methods such as waterstops or sealants as appropriate for
the prevailing conditions.
4-7. LOAD PATH INTEGRITY. Loads must be transferred from their point of application to the
foundation. All structural elements and connections along the load path must have sufficient
strength, and in the case of seismic resistant structures, sufficient ductility to transfer the loads
in a manner that will not impair structural performance. Most load path deficiencies are a result
of inadequate connections between precast elements, or between cast-in-place concrete
elements and precast elements. Connections are often required to:
Transfer shear from floor and roof diaphragms to the walls
Transfer shear from the walls to the foundations
Transfer shear between individual wall panels
Transfer tension caused by overturning forces
4-6
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