Bearing wall structures shall have vertical ties in all
load-bearing walls and longitudinal ties, transverse ties and perimeter ties at
each floor level in accordance with this section and as shown in Figure
1614.4.
FIGURE 1614.4 LONGITUDINAL, PERIMETER, TRANSVERSE AND
VERTICAL TIES
1614.4.1
Concrete wall structures. Precast bearing wall structures constructed
solely of reinforced or prestressed concrete, or combinations of these shall
conform to the requirements of Sections 7.13, 13.3.8.5 and 16.5 of ACI
318.
1614.4.2
Other bearing
wall structures. Ties in bearing wall structures other than those
covered in Section 1614.4.1 shall conform to this section.
1614.4.2.1
Longitudinal ties.
Longitudinal ties shall consist of continuous reinforcement in slabs;
continuous or spliced decks or sheathing; continuous or spliced members framing
to, within or across walls; or connections of continuous framing members to
walls. Longitudinal ties shall extend across interior load-bearing walls and
shall connect to exterior load-bearing walls and shall be spaced at not greater
than 10 feet (3038 mm) on center. Ties shall have a minimum nominal tensile
strength,
TT, given by Equation 16-46.
For ASD the minimum nominal tensile strength shall be permitted to be taken as
1.5 times the allowable tensile stress times the area of the tie.
|
TT =
wLS <= TS |
(Equation 16-46) |
where:
L = The span of the horizontal element in
the direction of the tie, between bearing walls, feet (m).
w = The weight per unit area of the floor or
roof in the span being tied to or across the wall, psf
(N/m2).
S = The spacing between ties, feet
(m).
[ALPHA]T = A coefficient with a value
of 1,500 pounds per foot (2.25 kN/m) for masonry bearing wall structures and a
value of 375 pounds per foot (0.6 kN/m) for structures with bearing walls of
cold-formed steel light-frame construction.
1614.4.2.2
Transverse ties.
Transverse ties shall consist of continuous reinforcement in slabs; continuous
or spliced decks or sheathing; continuous or spliced members framing to, within
or across walls; or connections of continuous framing members to walls.
Transverse ties shall be placed no farther apart than the spacing of load-
bearing walls. Transverse ties shall have minimum nominal tensile strength
TT, given by Equation 16-46. For ASD
the minimum nominal tensile strength shall be permitted to be taken as 1.5
times the allowable tensile stress times the area of the tie.
1614.4.2.3
Perimeter ties.
Perimeter ties shall consist of continuous reinforcement in slabs; continuous
or spliced decks or sheathing; continuous or spliced members framing to, within
or across walls; or connections of continuous framing members to walls. Ties
around the perimeter of each floor and roof shall be located within 4 feet
(1219 mm) of the edge and shall provide a nominal strength in tension not less
than
Tp, given by Equation 16-47. For
ASD the minimum nominal tensile strength shall be permitted to be taken as 1.5
times the allowable tensile stress times the area of the tie.
|
Tp =
200w <= ßT |
(Equation 16-47) |
For SI:
Tp =
90.7w <= ßT
where:
w = As defined in Section 1614.4.2.1.
ßT = A coefficient with a value
of 16,000 pounds (7200 kN) for structures with masonry bearing walls and a
value of 4,000 pounds (1300 kN) for structures with bearing walls of
cold-formed steel light-frame construction.
1614.4.2.4
Vertical ties.
Vertical ties shall consist of continuous or spliced reinforcing, continuous or
spliced members, wall sheathing or other engineered systems. Vertical tension
ties shall be provided in bearing walls and shall be continuous over the height
of the building. The minimum nominal tensile strength for vertical ties within
a bearing wall shall be equal to the weight of the wall within that
story plus the weight of the diaphragm tributary to the wall
in the story below. No fewer than two ties shall be provided
for each wall. The strength of each tie need not exceed 3,000 pounds per foot
(450 kN/m) of wall tributary to the tie for walls of masonry construction or
750 pounds per foot (140 kN/m) of wall tributary to the tie for walls of
cold-formed steel light-frame construction.
