While reviewing problems for the PE, I came across a question regarding wood design. The problem dealt with designing a wood member under Dead Load, Live Load, and Wind Loading. In the solution, they merely added these 3 loads together and used the duration factor. From my research, it seems...
Here is the scenario that brought about the question:
5 bays, 6 supports.
Steel cable spanning 20' between supports.
Dead Load on cable is near negligeable (0.1psf over 50' trib height)
Ice load takes that to 2.5psf.
Wind load is approximately 22psf horizontal.
obviously the wind load or ice...
But what if the loads on the extreme spans were the same magnitude of the load in the center span in your two scenarios? Doesn't the end support see the same force (horizontal load from one half of one bay) plus or minus the difference due to sag (for now to be neglected)?
Is it possible to say that one case will always produce higher reactions on the exterior columns than the other case?
Part of me wants to say that, if anything, the continuous case will produce lesser loads as there is more of an opportunity for sag due to the extra cable length (thus resulting...
We are having an internal discussion at my office regarding steel cables. Take the following scenario:
5 bays (6 supports) with a steel cable taking the loads. The loads may be on every bay, or may be on as little as one bay (or any combination in between). Does it change the max end reaction...
Thanks for the quick reply guys. I guess what I was getting caught up on was dealing with the amount of sag. I was thinking of just using a value for the sag and seeing what the force would be, but then I was worried that in application it might sag more or less depending on the material and...
I have a steel cable supporting a net. The entire system is about 60' high, but the application will have a steel cable supporting 50' vertical of netting. I have to treat the net as if it is seeing all of the wind load, which comes out to be about 23psf after all factors. The span is going...
Den, I agree fully. My first thought was, as you said, a typo of "4" instead of "3", but did not see it in the errata.
I guess I was hoping for any concrete confirmation (errata, published journal, etc) to back up what I do. Zones 2 and 3 do make the most sense as they would correspond with...
I was looking through ASCE 7-05 at the Components and Cladding for Gable Roofs with Theta <= 7 (pg. 56, figure 6-11B). Note 5 states the following:
I understand the first comment that you use Zone 2 for Zone 3. However, the next comment has me slightly confused. I read it that you should...
Thank you for the link and information. Unfortunately the equation regarding fillers seems to only be acceptable up to a 3/4" application where mine will be at least 3".
Sorry, the second bracket will be seeing a downward force (into the drawing) and a tensile force (up on the drawing). The shear is approximately 40 kips, and the tension is around 20 kips.
Hello,
I have a unique case where a bolt is going to see bending stress. Two "brackets" are being bolted together around double angels. One bracket will be connected to the double angle. The other bracket will be bolted to the first one. The problem is that the bolt will have at least 3" of...
But would the overburden (especially 1.46ksf)add to the compaction of the stone, making it "heavily compacted"? I know that sand increses its friction angle based on compaction and figured that stone would do the same.
I did find out, though, that my original question is moot as the passive...
Hello,
I am currently working on a design to resist horizontal loads through friction and passive pressure. I have gotten the system to work except that the soil is failing in shear. We are going to be using 3/4" crushed aggregate. If it is helpful I may be able to specify a certain type of...
Unfortunately it is a 235' clear span and the ground inside the structure will be removed (the structure is acting as a cover/air-tight seal aruond the operation) so nothing can span side to side to tie the building together. There are two controlling cases with almost the exact resultant. One...
Thank you for your help. The concept that I was grasping for, but could not remember, was that I get to use the weight of this system as overburden when calculating the passive pressure. This is going to help to greatly reduce the depth of the plates.
Thanks for all of the replies. It is meant to be a system to resist lateral and uplift forces from a 235' clear span fabric structure. The lateral loads come from both wind/seismic as well as thrust.
RWF7437: I understand that the coefficient of friction is not a function of AASHTO, but for...
Hello,
I have weight (140 kip +) that will be sitting on a precast plank (yet to be designed). The end goal is to have a system with an "equivalent coefficient of friction" of 1.0, so that 140 kips of weight can resist 140 kips of lateral force. It was suggested to place plates at the end of...
