UFC 4-023-03
25 January 2005
reinforcement at the third points of the floor height, not at the intersection with the floors
nor at mid-height.
When a column or a wall at its lowest level is supported by an element other
than a foundation, make a general check for structural integrity (i.e., make a careful
check and take appropriate action to insure that there is no inherent weakness of
structural layout and that adequate means exist to transmit the dead, live, and wind
loads safely from the highest supported level to the foundations).
4-2.9
Elements with Deficient Vertical Design Tie Strengths.
If it is not possible to provide the vertical design tie strength in a load-bearing
element, then apply the Alternate Path method for each such deficient element.
Remove each deficient element from the structure, one at a time and perform an AP
analysis to verify that the structure can bridge over the missing element. The amount of
element to be removed from the structure is given in Table 4-2 and additional detail is
provided in Appendix B.
Table 4-2 Removal of Deficient Reinforced Concrete Vertical Tie Elements
Vertical Load-bearing
Definition of
Extent of Structure to
Element Type
Element
Remove if Deficient
Primary structural
Clear height between lateral
Column
support member
restraints
acting alone
Length between adjacent
lateral supportsA or between
All external and
a lateral support and a free
Wall
internal load-bearing
edge.
walls
Clear height between lateral
restraints.
A
Using the definition of Ft in Section 4-2.5, a lateral support is considered to be:
1) a stiffened section of the wall not exceeding 1.0 m (3.3 ft) in length,
capable of resisting a horizontal force of 1.5 Ft, in kN per meter height of
the wall (0.45 Ft in kips per foot height of wall), or,
2) a partition of mass not less than 100 kg/m2 (20.6 lb/ft2) at right angles to
the wall and so tied to it as to be able to resist a horizontal force of 0.5 Ft,
in kN per meter height of the wall (0.15 Ft in kips per foot height of wall).
4-5
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