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I was just curious how everyone handles the concrete detailing at an overhead door where the interior concrete slab meets the driveway. We are designing the foundation and slab for a prefabricated variable depth column building that will be used as a heavy highway maintenance facility (snow...

Buggar, so how do you handle mechanical splicers and spiral cages when dealing with large diameter bars? Do you set spiral pitch to be greater than a typical mechanical splicer length (and typical can vary depending on type of mechanical splicer used), increase spiral cage diameter in region...

Shaft is #14 bars and column is #11, so it is using transitional mechanical splicers. Shaft is 6" larger diameter than column (6' shaft, 5.5' column). The splice occurs 2' and 4' (alternating splicer locations) above the top of the shaft. Attached is partial drawing. The diameter of the...

This may be a contractor issue, but figured I'd get some insight from other designers on here. We did some plans for a bridge that used 6' diameter drilled shafts with #14 vertical bars. The contractor ordered the bars straight with the ends threaded where the mechanical splice occurs just...

Agree bootlegend, my description including the node is likely confusing others. It is 100k on each side of the node (each member). I thought it was 100k per bolt as well, but others thought it was additive at the joint and therefore divided among the bolts. They argued how you can have 200k...

Yes, that 100k force is the force at the end of the member (which essentially is at that node) from the member detail/output. Member to the left of midspan has 100k tension, and member to the right of midspan has 100k tension. For a bolt on each side of the splice (2 bolt for entire splice), is...

A bit of office discussion around here and surprisingly the opinions are split down the middle, so curious what you all think. If you were to analyze a Pratt truss in a program like RISA and determine the max tensile force (lets say 100k) in a lower chord midspan at a node, for a connection...

Thanks Josh. It was my understanding that one either uses the Open Signs/Lattice Framework coefficient and apply it to leeward and windward columns (coefficient is lower and thus smaller pressures), or use the Trussed Tower coefficient (which results in higher pressures) and only apply it to...

We are designing agriculture support towers with a square footprint in RISA. We have calculated our wind pressure (67psf for this 6'x6' footprint) from the formulas in ASCE 7-10 and utilized the Trussed Tower Force Coefficient from Fig 29.5-3. I am a little confused on if the wind pressure is to...

Thanks for the info. I'll look into that Journal article!

What is everyone's take on unbraced lengths when modeling towers that utilize single angles forming an "X" for bracing between columns? The intersection point will have a through bolt, so my thought is the bolt will reduce the effective length for buckling vertically but the buckling will still...

Unless I'm misinterpreting things, all I can find in the ACI code is openings in new slabs without beams. Essentially it is a continuous slab that is only supported by columns in each corner. What is typically done when you have a slab supported by walls on all four sides? I'm struggling with...

After I posted this I realized I should have read the help file in RISA. Thanks for the contribution Josh. I don't have an answer for gmailman1 though, maybe you can assist.

I'm modeling a steel frame structure (pipe bridge) and this is both a question related to RISA as well as structural engineering. Attached is a screenshot of my model. In RISA there is four different unbraced lengths you can input for the member info, Lb yy, Lb zz, Lcomp top, and Lcomp bot. I...

I'm using AISC 9th Ed - ASD. I'm quite a bit over in block shear, thus my question about welding the clip angles to over triple the total thickness. The commentary in the LRFD 3rd Ed mentions checking block shear around the periphery of welded connections, so I'm thinking if the block shear...

I have a project that involves an existing structure that the client wants to add more loads to (industrial application). It is essentially a steel support structure with 6 columns (2 per side) a continuous beam atop the three columns, and coped beams connecting the two continuous beams (at each...

One last question for the masses. I've decided to use the inverted channel atop the steel deck since this generator needs isolators at each corner of the skid and the spacings on the isolators is within a couple inches of the joist spacing, so the channel just made sense. My question is, when...

Those details are from the existing plans. So do they cut the decking or is it located somehow between puddle weld and slid between the joist and decking? Sorry for all the questions.

Thanks for the info RFreund! Triangled, that involves cutting out portions of the steel decking to access the area between the deck and the top chords, correct? I've used details such as what you describe (coped-end angles going over the top chord joist angles), but these have always been new...

Good info guys. Lets say we utilize the upside down channel like in Fig 5.4.2 in the Vulcraft manual to span between joists. What is used in the opposite direction (parallel with the joists)? With an existing structure, its not like we can provide blocking on the underside of the decking like...