30 November 1998
(PL + PT )n s ≥ Psy
10. PANEL ANCHORS. Panel anchors must be installed on both sides of the shear panel columns
because the columns by themselves have inadequate shear capacity. Furthermore, if the column were
simply fastened to the track, the track would be loaded in bending, due to uplift. The track is very weak in
bending and this would violate the guidance stated in Paragraph 6c. Therefore, anchors consisting of
angle iron sections shall be welded to both sides of the column at both the top and bottom of the columns
to provide the required panel anchorage. Loose steel plates are laid over the horizontal portion of the
angle sections. The angles and plates shall be drilled with through holes and anchored to the supporting
diaphragm above and below the shear panel using embedded anchor bolts. See Appendix D (Figures D4
through D9) for examples of this anchor configuration.
a. Anchor Shear Capacity. Columns have insufficient shear capacity by themselves, and require
additional shear capacity from their anchorage detail. This will require the installation of angle iron
anchors on both sides of the columns, such that one leg of the angle extends beyond the critical shear
plane. For screwed fastener connections, the critical shear plane is along the horizontal row of screws
closest to the track in the diagonal strap-to-column connection. For the welded connections, the critical
shear plane is along the strap-to-column weld near the track. The angle iron anchor shear design
strength, VA for a single angle is defined as follows:
VA = 0.6φ vFAy bc t A
φv = 1.0.
FAy = the anchor angle iron yield strength.
bc = the width of the angle, which equals the out-of-plane width of the column.
tA = the thickness of the angle.
The total design shear strength, VT must exceed the maximum shear panel horizontal seismic force Phumax
(Ω0QE). All anchors are made up with two angles, on either side of the column, so that VT may be
VT = VC + 2VA ≥ Phu max
VC = the column shear capacity determined in according to Equation C-46 in Appendix C.
Phu max = Ω 0 QE = Fsu max n sb s t s
b. Anchor Angle and Plate Design. The most critical load condition for anchors is when the
effects of gravity load and seismic forces counteract each other. This load condition is expressed by
The selected angle and plate anchors shall resist the applied shear and uplift forces. These anchors will
also provide limited moment resistance. The angles and plates will yield in flexure between the anchor
bolts and bend in the angle, but will not fail in a brittle manner. This limited moment resistance will slightly
widen the hysteretic envelope in the load deflection performance of the panel. The angles and plates can
yield significantly through many cycles with no loss of shear and uplift resistance (some loss of moment
resistance). The maximum weld thickness to the column shall be used, which is based on the thickness
of the column material, as indicated in Table 3-3. The panel anchors shall be constructed using angle