25 January 2005
STEEL TIE FORCE REQUIREMENTS.
All buildings must be effectively tied together at each principal floor level.
Each column must be effectively held in position by means of horizontal ties in two
directions, approximately at right angles, at each principal floor level supported by that
column. Horizontal ties must similarly be provided at the roof level, except where the
steelwork only supports cladding that weighs not more than 0.7 kN/m2 (14.6 lb/ft2) and
that carries only imposed roof loads and wind loads. Ties should be effectively straight.
Arrange continuous lines of ties as close as practical to the edges of the floor
or roof and to each column line; see Figure 5-1. At re-entrant corners, anchor the tie
members nearest to the edge into the steel framework, as indicated in Figures 5-1 and
Strength Reduction Factor Φ for Steel Tie Forces
For the steel members and connections that provide the design tie strengths,
use the appropriate tensile strength reduction factors Φ from the 2003 version of the
Manual of Steel Construction, Load and Resistance Factor Design from the American
Institute of Steel Construction (AISC LRFD 2003). For example, use a strength
reduction factor of 0.75 for block shear at a bolted connection.
Horizontal Steel Ties
The horizontal ties may be either steel members, including those also used
for other purposes, or steel reinforcement that is anchored to the steel frame and
embedded in concrete, designed per ACI 318-02 and meeting the continuity and
anchorage requirements of Section 4-2.4.