bolts tension members aisc / lrfd wildcard 100 200 300 400 500
TRANSCRIPT
BOLTS TENSION MEMBER
S
AISC / LRFD
WILDCARD
100 100 100 100
200 200 200 200
300 300 300 300
400 400 400 400
500 500 500 500
In 2 words, what is the reason for calculation of a reduction
coefficient, U, for effective net area, Ae?
SHEAR LAG
Name the three strength limit states for tension members.
Yield of the gross cross section, net area fracture, and block
shear
What is s2/4g and how is it used?
It is a ‘length correction’ for calculation of net area when considering net area fracture
paths for staggered bolts.
For this W18x40 subject to tension, with bolted splice plates at the top
and bottom flanges, what would you use for connection eccentricity,
x?WT9x20x=2.29”
AISC Table 1-8 [p.1-61]
2.29”
USE AISC MANUAL
Which block shear path would you NOT check and why not?
#1, since the middle bolt would also have to be sheared
1
2
3
Name the recommended serviceability limit for tension
members based on ease of handling and prevention of
excessive sagging or vibration.
L / r less than or equal to 300
What is the general rule of thumb that determines
whether or not a hole can be punched?
dhole greater than tplate (or element) (often quickly check dbolt ≥ tplate)
What is the definition of ‘gage’ length?
Distance between bolts perpendicular to the direction
of loading
What is the f factor associated with fracture, what is the f
factor associated with yield, and why is one lower than the
other?0.75, 0.9, lower resistance factor results in a higher
margin of safety for brittle limit state of fracture
If Tu=120 kips, and the service load, T, is 25% dead load and
75% live load, what is the value of T?
Tu=120 kips=1.2D+1.6LL=3D
120 kips = 1.2D+1.6(3D)=6DD=20 kips
T = D + L = D + 3D = 80 kips
Bolted splice plates are typically ‘short’ with limited
inelastic deformation. Therefore, we apply this ‘rule’
in our calculations as an additional factor of safety:
The “85% rule”Ae = An ≤ 0.85 Ag
AISC J4.1
In this equation for capacity of a tension rod or bolts in tension, one 0.75 is the
resistance factor; what is the purpose of the other 0.75?
The other 0.75 accounts for the reduced cross-sectional area of the
threaded portion.
bun AFT )75.0(75.0
Why does the equation for bearing capacity of a bolt include Fu of the plate or
connected part?
Derivation of the bearing resistance equations considers
splitting failure of the plate
What are the workable gage
distances for this L8x4x1/2 with 2 bolts in the long leg and 1 bolt in the short leg?
3”, 3” and 2-1/2”AISC Table 1-7A
2-1/2”
3”
3”
USE AISC MANUAL
In the above equation for shear of bolts with threads excluded, the 0.563 includes a 0.625 for
shear and a 0.9 for what?
Connection length effect
0.75(0.563 )bn u bR F mA
If bolts are used in combination with welds, they should be
designed as slip critical. Why? The bolts will not bear on the plate
unless welds have failed and the bolts can slip. Therefore, the design should be based on the bolts’ slip-critical capacity,
rather than bearing-type (shear and bearing) capacity.
In this equation for slip-critical connections, the resistance factor, f, varies depending
upon what?Hole type (e.g., standard, oversized, short- or long-
slotted)
n u f b sR D hT n
In the AISC Spec., the minimum
edge distance, Le, depends on
what?
The diameter of bolt (AISC Table J3.4)
Le
For A325N bolts in bearing-type connections subject to
combined shear and tension, the tensile stress demand must
be less than the available tensile strength, fF’nt, which
also must be less than or equal to ___?f0.75 Fu
b = (0.75)(0.75)120 ksi=67.5 ksi
Even though the upper limit on the block shear limit state
includes a rupture component and a yield component, it is
primarily a rupture limit state. Therefore, the f factor is ___?
0.75