I am engineering an Ordinary Moment Frame for an industrial structure in a high seismic region. The SDS for the site equals 1.0. According to AISC 341 Section 4.2(a), I have to engineer the moment connection for the expected flexural strength of the beam. This load is high, so AISC 341 Section...
My company is engineering some foundations for an industrial facility. The geotech report states the upper ten feet of existing grade is loose and gives an allowable bearing capacity of 1,500 psf. Our client hired a third party engineer to make foundation recommendations for the site. This...
I am designing the anchor rods for a pre-engineered metal building. The PEMB engineer placed x-bracing in the end walls. For the load case with wind load parallel to the frame, they are giving me shear parallel to the frame from the x-brace and shear perpendicular to the frame from sidewall...
My company does a lot of foundation designs for horizontal vessels, and I am looking for some insight on anchor rod design for these vessels. The vessels typically sit on two saddles, one on each end. One of the saddles is slotted to allow for thermal growth of the vessel. We normally put a...
My company uses an old design guide to engineer foundations for dynamic equipment. The design guide assumes the foundation is rigid. To make the assumption that the foundation is rigid, the guide recommends providing a foundation thickness greater than or equal to 2’-0” plus the longest mat...
We have recently had several requests from clients asking to place skids on gravel pads in lieu of using concrete foundations. These skids range in size and service from 5,000 pounds holding nothing but piping to 200,000 pounds with reciprocating compressors and related equipment. Assuming the...
I am designing a fire-rated partition wall in a mine roughly 1200 feet below grade. In a normal building application, I would design for the code required 5 psf minimum (IBC 1607.13). Does anyone know if the pressure would be greater for any reason because I am 1200 feet below grade?
I am designing a retrofit for a steel pipe rack built in the late sixties or early seventies. The pipe rack was designed (or likely built without being designed) in a stacked fashion. The bottom level beam sits on top of the columns. The next level column sits on the beam. The...
I am designing the pipe supports for 24" diameter schedule 80 pipe full of liquid. The pipes are long, and will experience a decent amount of thermal growth. The client has requested placing the pipe on Tulsa Pipe Supports, which are wedge blocks made of cured Chockfast Red Epoxy Grout. I...
A co-worker and I got into a debate yesterday about one of the foundations he designed. The foundation acts as a sleeper type pipe rack. It consists of an 8" thick by 2'-0" deep grade beam with a length of 7’-6”. At its worst case, the concrete sticks 1'-0" out of ground, which leaves only...
I am designing some anchors for a piece of equipment using ACI Appendix D. The vendor requires a pre-tension load. Placing the pre-tension on the anchors will place tension into the concrete as well. The pre-tension is much greater than any load I will be placing on the anchors. When...
Does anybody have a good design method for utilizing Appendix D on round piers? I am mainly looking for what to use for edge distances (camin, camax, ca1, ca2). I also need to figure out how to calculate effective embedment and and effective edge distance for ca1. Effective embedment comes...
I am performing a four bolt end plate moment connection design per AISC Design Guide 4. The design guide uses yield line theory to size the plate and column flange thickness. Reading through the text at the beginning, the design method tries to eliminate prying action by sizing the plate and...
ACI 318-08 D.5.2.9 allows the use of supplementary reinforcement to develop concrete breakout. It says to use a strength reduction factor of 0.75, but does not specify to what this 0.75 factor applies. In the past, I have used equation D-3, (Ncb=n*Ase,N*futa), and used a phi-factor of 0.75 to...
ACI 318-08 Section D.6.2.6 requires an edge effect modification factor to be placed on the shear breakout strength of a single anchor or group of anchors. The factor is dependent on ca1 and ca2 values. When a set of anchors is on a pedestal and has two ca2 values, do we need to use the...
I am currently designing a pipe rack in a seismic design category C location. The pipe rack falls under Chapter 15 of ASCE 7-05 as a nonbuilding structure similar to a building. Section 15.4.1-1a says a system shall be selected from Table 12.2-1 or Table 15.4-1. The section then goes on to...
I am designing an addition to a manufacturing facility in a moderate seismic region (SDC C). The building is approximately 440'x130'. I am adding a double row of columns to break the addition into two separate structural elements. The dimensions of one of the elements is 300'x130', which is...
I am currently designing a building addition located in Arkansas. The building footprint is approximately 440'x128', giving it a length to width ratio of 3.44. In AISC Steel Design Guide 7, James Fisher recommends a maximum length to width ratio of 3.00 for both diaphragm and horizontal...
