Does anyone have a design methodology or can anyone point me to a design guide for the design of partial-depth web and flange stiffeners according to the 2010 Edition of the AISC Steel Code section J10? I cannot find any guidance on how to design these elements anywhere. The description of the...
We have an elevated concrete slab on form deck in a large industrial building. How often do you space the control joints? How often do you space the expansion joints? Where do you locate the control and expansion joints? I imagine that the location of the joints will differ with the orientation...
We have a large piece of mechanical equipment that is self supporting and weighs approximately 300k. The manufacturer did not supply seismic loads. We did the superstructure design but not the foundation design. We need to supply the foundation engineers with the seismic loads. Which chapter in...
I am designing the support structure for a circular storage bin that is 54 ft. in diameter and 100 feet tall. Which provision in ASCE 7-05 should be used to calculate the wind load on the bin: Section 6.5.12.2.1 Rigid Buildings of All Heights (using Kd=0.95); or 6.5.15 Design of Wind Loads on...
I am collaborating on a spreadsheet for the design of monorails for underhung hoists. My colleague is a bit older than I am and has some formulas and information that we cannot verify. He has been working in the industrial sector and this is the way it was always done. I would like to verify...
The hillside along the south wall of a big box supermarket is sliding away. The geotechnical engineers are stabilizing the hillside. We are analyzing an existing 12" load-bearing reinforced concrete masonry unit wall that is 20 feet high and is 5.5" out of plumb to determine if the wall is safe...
I was asked to design the steel support frames for 3 machines in the UK for a steel mill. The machines and steel support frames will be built in the US and shipped to the UK. The machines are 43'x12' and the support frames need to be 15' high. I will also be designing platforms and stairs to...
I haven't designed rod bracing but the situation seems to present itself, so here it goes. I have a couple of questions.
What do you you use for pins for clevises for rod bracing? Bolts, rods? How do you detail a rod so that it doesn't slide out horizontally perpendicular to the gusset? Are...
I have an existing building where I need to put rod X-bracing. Does anyone know of a detail for connecting rod bracing to a tube column? The other end, the rod bracing will connect to a wide flange but the web is parallel to the rod, i.e. the rod will connect to the flange?
I am doing concrete repair in a wastewater treatment tank containing run-off containing oil and gas and some human waste. I am having a hard time finding repair mortar for overhead and vertical repairs that will withstand exterior exposure, freeze thaw and sulfate attack. Does anyone know of...
I am designing a strip mall with rather high parapets. The mall is a steel framed building with steel bar joists on steel beams. The roof is a built-up roofing system. The typical parapet height is 5 feet and the parapet at the mall entrance is 10 feet. We need to brace the 10-foot parapet...
I am currently working on an expansion/modification to an existing shopping mall. Unfortunately, the original structural engineer neglected to use bracing of any kind for lateral support. The lateral resisting system consists of 8" CMU tied to the column with wall anchors and no angle at the...
I haven't done that much steel design, mostly concrete. I have been doing more steel design lately. I have read on here that you cannot control drift in moment frames like you can with braced frames. I understand this. However, what is the maximum drift limit you use for desing using moment...
For steel braced frames, what is the maximum aspect ratio (bay length/story height) that you would use for X-braced frames? What is the maximum aspect ratio you would use for K-braced frames? When do you typically use each one (i.e. in which situation would you choose K-bracing over...
Most of my design has been with concrete but when designing steel buildings, there is one thing that bothers me. When designing and detailing a steel beam at the roof level along the exterior perimeter of the building with joists parallel to the beam, we show an angle kicker from the bottom...
A long time ago when I was designing larger buildings, I had to design a lot of combined footings. One time however, I had to design a strap footing. I can't remember why I had to use a strap instead of a combined footing. Can anyone explain when it is appropriate to use a strap footing over...
I am doing a take-off for concrete columns with spiral reinforcement. I have never designed with spiral reinforcement but I now how to calculate the reinforcemtne ration. However, I do not know how to calculate the actual length of the rebar for a quantity. I have looked in the ACI detailing...
The process guys have located a 6" and 10" drain under our 46'x46'x24' concrete tanks. The contractor wants to use stainless steel pipe because he has it in stock. I have design guides for ductile iron pipe but not stainless steel pipe. Does anyone know of a design guide for buried stainless...
I am designing concrete tanks for a human wastewater treatment facility. Would you use epoxy coated bars in the concrete for a tank containing human wastewater? ACI 350R-89 states that the concrete does not need to be protected from human wastewater but does not mention anything about the...
We are designing a steel walkway to attach to the side of a concrete tank wall. To attach the walkway, we are embedding plates in the concrete wall. Supports for the walkway will be welded to the embedded plates. The embedded plates are 1/2" thick. We are welding the flanges (thickness =...
