CEMP-E
TI 809-07
30 November 1998
Equation D-25 is not included in the guidance in Chapter 3 or Appendix C because the format of
manufacturer' test data is unknown and may need to be evaluated on a case-by-case basis as
s
shown in this example. Table D-12 provides values for this nominal shear strength based on
manufacture' fastener shear strength and Equation D-25. If these values are less than other
s
nominal values based on equations C-48 through C-53, these values will control and will be used in
Equation C-47 to calculate the design shear per fastener, Ps. Table D-12 presents Ps based on the
overall minimum nominal shear or pull over strength. In this example problem the manufacturer'
s
fastener shear strength data controls the nominal fastener shear strength for all panel configurations
except for the one shown on the first row of Table D-12.
The number of screws at each diagonal strap-to-column connection, nscrews, shown in Table D-12, is
very large and the use of larger screws or a welded connection should be considered. Still, each of
these connections may be constructed within the overlap area of the strap and column and within the
spacing and edge distance requirements given above. The most difficult joint to lay out is the one in
the first row, which is based on installing diagonal straps on only one face of the shear panels. The
column is 4 inches wide and the strap is also 4 inches wide and is oriented at an angle based on the
width, W and height, H of the overall panel given in Table D-5. A layout of the fasteners is selected
that will keep the column critical shear plane as close as possible to the track, while maximizing the
net area for rupture strength evaluation. A trial layout is shown in Figure D-4. This connection has 5
fasteners at the first row against the track, and 6, 6, 6, 6, 6 and 5 fasteners in the subsequent rows
moving away from the joint. These fasteners are spaced at 9/16 inches on center horizontally and
inch on center vertically. The other diagonal strap-to-column screwed connections in Table D-12 are
laid-out in a similar manner and are shown in Figures D-5 D-8.
b. Design Rupture Strength Between Fasteners. Figures D-4 through D-8 show the critical
diagonal strap rupture surface, for which the rupture strength is calculated. The rupture surface
located along the inside edge of the column and along a horizontal plane will be loaded at
approximately a 45 degree angle to the rupture surface. Therefore the average of the shear strength
and tensile strength expressed by Equations 3-17 and 3-18 are used for determining the design
shear/tension strength, VT along this surface as follows:
VT = 0.8φ tFuAnvt
(Eq D-26)
v
Where:
φ t = the shear tensile rupture resistance factor, equal to 0.75
v
Anvt = the net area subjected to load at approximately 45 degrees.
The design shear/tension, VT and tensile, T rupture strengths are calculated according to Equations
D-26 and 3-18, based on a trial layout of the fasteners in each diagonal strap-to-column connection.
The use of #10 screws result in a very large number of screws at each connection as seen in Table
D-12 and Figures D-4 through D-8. The screw pattern must stay within the spacing and edge
distance limitations given above.
When the strap-to-column rupture strength is evaluated based on Equation 3-19, as modified with
Equation D-26 the resistance factors in Equations D-26 and 3-18 may be increased to 1.0, because
of the ASTM minimum material requirement on Fu/Fy. All of the trial diagonal strap-to-column
connections do not meet Equation 3-19, as can be seen by comparing Psy and (VT + T)ns in Table D-
13. The achieved resistance factor (φ ) for Equation D-26 and 3-18 is shown in Table D-13 for each
a
of these connections. This achieved resistance factor is expressed as follows:
Psy
φ=
(Eq D-27)
a
nsFu (0.8Anvt + Ant )
rd
This factor is well below 1.0 for all connections except the first row (3 Floor case with a diagonal
strap on only one face of the panel). The shear panel shown in the first row (Figure D-4) is therefore
an unacceptable configuration, and the design shown in the second row (Figure D-5) is selected for
D-13
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