@ jayrod12, If I release the torsional restraint at one end, torsion still develops in the members, it just goes to zero at that end. Perhaps the torsion is generated through top slab (modeled as 6" concrete plate elements) or through the bridging in the interior span? Even if I remove these...
TLHS, this seems like a good idea but I am not sure how to apply this in my RISA 3-D model. It seems RISA limits the release of torsion to one end of the member. Do you have any suggestions on how to release the torsional restraint on the joints?
@ KootK:
1) What's the joist span?
3-span continuous beam w/ exterior spans = 17'-3" and interior span = 35'. The interior span has bridging perpendicular to the joists at the 1/3 points.
2) What's the joist width?
7"
3) What's the total depth of the system.
18" (6"Slab + 12" rib)...
MIStructue IRE, Good point. I am not sure where the torsion on the joists is coming from in my structural model. A free body diagram would not indicate any torsional forces.
Do nonprestressed concrete one-way joists beams that meet the requirements of ACI 318-14 Section 9.8 need to be designed for torsion? My structural model indicates that the members are over the threshold torsion, but the model does not recognize the members to be part of a one-way joist system...
Ingenuity, what you have clouded in the top Photo is actually a diagonal truss element beyond the crane rail beam. This crane rail beam (left side of bottom photo) only has vertical hanger rods and no diagonal braces. In the bottom Photo, the clouded section on the right crane rail beam is a...
In regards to my original question regarding Cb, does it simplify to alpha_m = Cb = 1.35 for a configuration as shown Figure 3a.b2? That is my interpretation based on Equation 21a on page 9 from Ingenuity's referenced University of Sydney Research Report R883 by Trahair.
Agent666, you are correct that I am trying to obtain the best possible Cb value in order to increase my available strength. Currently, I am unable to access the papers from the links above. What is the equation given that references alpha_m? Also, I am not sure how the k value from Eq. 7 of...
The adjacent crane rail beam (connected by hoist bridge beam) has diagonal bracing from the top flange of the crane rail beam up to bottom chord of the roof truss. See attached Photo for reference. Supports are at 24'...
The crane rail beam is existing and there are no plans available. See attached Photo of the hanger connection for reference. The task is to evaluate the crane rail beam for another load in addition to the rated hoist capacity. I have determined the flexural capacity of the crane rail beam...
Is a crane rail beam that is supported at each end by hanger connections that attach only to the top flange of the beam considered to be braced for the purposes of the calculation of the lateral-torsional buckling modification factor, Cb? With these end conditions, can you use AISC 14th...
