A few years ago my engineering firm starting placing longitudinal reinforcing for non-load bearing wall footings in two layers - two bars in the bottom of the footing, and one bar in the top. I am referring to footings that are typically about 24" wide by about 12" thick, and technically are...
Does anyone have advice on selecting a grade for old lumber that was sawmilled before the current grading system? I am looking at engineering a renovation of a 100 year old building, constructed with lumber which is obviously a better grade than #2 SYP. Are there experts who can evaluate the...
I noticed that MasterSpec doesn't allow a spray cure compound for floor slabs to receive a floor covering, i.e. a form of wet cure is required. I know that dissipating spray curing compounds sometimes do not dissipate if they are not exposed to light and foot traffic, but they still seem to be...
I am designing a safe room for tornado loads and wondered how other engineers are calculating the force due to 2x4 missile impact. I think the appropriate formula is F = 1/2 x m x V x V / S, where S is the slowdown distance. The appropriate mass seems to be 15 lbs / 32.174 = 0.47 slugs, and...
I'm trying to figure out what has caused this crack pattern in a precast stadium beam. The cracks do not look like tension or shear cracks - maybe they are just shrinkage. The beam is about 3 feet deep and 14" wide. The predominant pattern is 3 or 4 longitudinal, with some random vertical...
I'm curious as to the different ways to hire a special inspection firm. Many of our clients prefer to hire a qualified favorite firm and just pay their hourly costs on a monthly basis, but some clients prefer to have a "fixed fee." I have found that a fixed fee is nearly impossible to arrange...
Just wondering if anyone else has noticed that Building Code Requirements and Specifications for Masonry Structures has added an appendix on design of masonry infill walls. Masonry infill walls are not allowed to be used as shear walls if they have any openings at all in the wall. Actually...
I am reviewing an old open structure, framed with wood posts and beams. There are no elements to provide lateral stability other than knee braces at the columns. Would this structure be permitted in ASCE 7, and what category would it fit in in Table 12-2-1? My SDC is C. I know this structure...
The bottom of a cast in place grandstand is deteriorating. The paint is delaminating in several spots because the concrete is extremely soft and crumbling. Not sure if deicing chemicals were ever used on the top surface, which is also painted and looks sound. Anyone have any ideas for the...
I am designing an addition which requires removing about 100 feet of load bearing wall (also serves as shear wall for a single story bldg). I'm replacing it with posts and beams and making frames rigid to handle the lateral loads. This wall supports bar joists spanning about 25 feet. My past...
What values are reasonable for an office type floor, not a warehouse? According to ACI Concrete Knowledge Center, Ff = 20 and Fl = 15 are "conventional numbers." This would be equal to a 5/16" gap under a 10' straightedge, which seems excessive, but maybe that is typical. I would like to hear...
My philosophy is not to place a building over an existing active corrugated metal pipe carrying storm water unless I encase the pipe in reinforced concrete. Is this being too conservative? My thinking is that the lifespan of the pipe is shorter than the building, so it must be encased to...
I've got a note on some 1933 drawings that says "Reinforcing steel to be new billets 20,000 lb. grade". Does anyone know exactly what that means? Should I assume 20,000 psi yield?
Is there a relationship between the angle of internal friction and the sliding friction factor? Otherwise, how do you calculate the sliding friction factor?
I would like to specify quality control for a concrete slab with FF25/FL20. Does anyone have a reference to the proper test procedures to verify specified slab flatness has been obtained?
I just inspected an 8" cmu wall, built in 1973, that has a strange deterioration going on. The block has had several "pops" take place over the years. In one room I looked at there were at least 1 or 2 per block. Something obviously is expanding within the block to cause this. When I checked...
In the Structural Engineering Handbook by Gaylord & Gaylord, there is a formula for moment in a lateral loaded pile, M=Cm x Qhg x T. Cm is defined, but I can't find a definition of T, other than z=x/T. Can anyone tell me a definition for z, x, and/or T. This is found on page 5-84 of my old...
What would be an effective floor width to resist a line load parallel to the floor deck? For example, a masonry wall on a composite floor slab. There is a good design example for a line load perpendicular to the deck in "Designing with Steel Joists, Joist Girders, and Steel Deck" by Fisher...
