30 November 1998
the 3rd floor shear panels. For the other shear panels the resistance factors are above 0.75, but are
judged to be acceptable because of the ATSM requirement on Fu/Fy.
Table D-13. Screwed Connection Rupture Strength and Welded Connection Design.
Strap Tension Tension Design
Force Net Area
c. Welded Connection Design. Figure D-9 shows a trial layout of a welded diagonal strap-to-
column connection. All welds in this connection have a thickness, t equal the thickness of the
diagonal strap (0.075 inches). This is much less than 0.15 inches, so weld failure through the weld
throat (Equation C-57) need not be considered. Details on the strap and column sizing are given in
the last row of Tables D-5 and D-8. All welds have a L/t ratio much greater than 25, so that Equation
C-55 is used to define the longitudinal weld capacity. The top edge of this connection shown in
Figure D-9 is loaded in the longitudinal direction and its design shear strength is defined according to
Equation C-55. The diagonal edges at the end of the diagonal strap are loaded close to 45 degrees,
so that an average of Equation C-55 and C-56 defines the weld capacity along these edges.
Therefore, the longitudinal/transverse design shear strength (PLT) may be expressed as follows:
PLT = 0.87φLFu
φ= 0.58, which is an average of the resistance factors for longitudinal and transverse loading
expressed in Equations C-55 and C-56.
Table D-13 gives the weld thickness, length of welds loaded in the longitudinal and
longitudinal/transverse directions. Table D-13 also gives the design capacity of the longitudinal,
longitudinal/transverse and combined capacity ((PL + PLT)ns) expressed by Equation 3-21, as modified
by Equation D-28. Comparing the total shear capacity and strap yield strength, Psy shows that this
connection detail meets the requirements of Equation 3-21.
D12. SHEAR PANEL ANCHORS. Panel anchors must be installed on both sides of the shear panel
columns. These anchors are installed at both the top and bottom of the columns to anchor the panels
to the floor diaphragms both above and below the shear panels. The anchors are needed to provide
the required shear, uplift and moment resistance from the eccentric diagonal strap loading of the
anchors. The anchors will also provide limited moment resistance that will allow some moment frame
action of the columns, providing system redundancy and a widening of the hysteretic load/deflection
envelope. The anchors consist of angle iron sections welded to the column, with loose steel plates
that are both bolted to the diaphragm using embedded anchor bolts (see Figures D4 through D9).
a. Anchor Shear Capacity. All of the trial columns shown in Table D-8 have insufficient
shear capacity by themselves and require additional shear capacity from their anchorage. The
anchor angle irons increase the shear capacity. Each angle leg extends beyond the critical shear
plane. Figure D-4 shows such an anchorage made up with 6 inch long, L 4 x 4 x inch angle iron
sections welded to both sides of each column. The anchor shear capacity is defined according to
Equation 3-22, and the combined column and anchor shear capacity is defined according to Equation