Presentation on theme: "BOLTS TENSION MEMBERS AISC / LRFD WILDCARD 100 200 300 400 500."— Presentation transcript:
BOLTS TENSION MEMBERS AISC / LRFD WILDCARD
In 2 words, what is the reason for calculation of a reduction coefficient, U, for effective net area, A e ? 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 s 2 /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? WT9x20 x=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? d hole greater than t plate (or element) (often quickly check d bolt t plate )
What is the definition of gage length? Distance between bolts perpendicular to the direction of loading
What is the factor associated with fracture, what is the 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 T u =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+1.6L L=3D 120 kips = 1.2D+1.6(3D)=6D D=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.
Why does the equation for bearing capacity of a bolt include F u 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 includes a for shear and a 0.9 for what? Connection length effect
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,, varies depending upon what? Hole type (e.g., standard, oversized, short- or long-slotted)
In the AISC Spec., the minimum edge distance, L e, depends on what? The diameter of bolt (AISC Table J3.4) LeLe
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, F nt, which also must be less than or equal to ___? 0.75 F u b = 120 ksi 0.75 F u b = 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 factor is ___? 0.75