joemarch,
Since floors usually give more problems when their natural periods are longer (more flexible floor system), the shorter joists might give an apparently more rigid answer. I would try using the longer joists for calculation, just so the upper bound on flexibility can be investigated...
LalyaZ,
The Army Corps of Engineers in Vicksburg, MS, has done a lot of blast mitigation research. You might try getting hold of some non-secure analysis programs through them.
David
MMOT,
This would essentially be the same as a tuned mass damper (sloshing type), which would actually be a positive factor in resisting seismic shears. You might want to search on this subject to get further input.
David
tw,
One reason these types of canopies don't perform well under extreme wind loadings is that, despite designing them to the ASCE wind load provisions, there are peculiar dynamic forces acting on them that are not usually taken into account. Some of these unrecognized force criteria include: a...
dooron,
AISC allows finger shims, up to 1/4" in thickness, in any type of connection, including slip-critical connections. Anything over 1/4" must be extended outside the margins of the connection and fillet welded to the base metal section.
David
marthab,
Be very careful when considering using options 1 and 2, as these could be rendered ineffective by later floor modifications (saw-cutting), which often occur in industrial buildings. The present use, and intended future use, of the building should guide you in this decision. Since it...
arctic,
The AWS (American Welding Society) homepage (www.aws.org) will link you to their catalog section, where all of the specifications starting with "D10." relate to various pipe welding topics. The API (American Petroleum Institute) homepage (www.api.org) will link you to their...
pylko,
We ran into a situation similar to this a few years back and the tubes used there were transite pipe sections. I wonder if those you encountered might be transite also?
David
dison,
We have used contractors with low-headroom drill rigs on some of our projects which need only 16 feet of headroom. There are some that go even lower - as low as 12 feet. As for lateral clearances, you need the width of the drill rig (about 8 feet), plus the area to dump the spoil...
Pylko,
I agree with Ron; our practice is to treat the single shear bolts as erection bolts only, and do not figure them in the equation when evaluating offset connection capacity. Evaluating the connection as has been suggested seems only necessary in the (uncommon) event that there is not...
Mark10,
The main reasons our group details mats this way are twofold:
The bend provides anchorage for developing the rebar for moments near the edge of the mat from wall (line) loads.
The laps in the bends allow the top and bottom bars to be tied together for constructability location and...
Pouring,
In the past we have used channels, oriented vertically, with their legs turned toward the column, to anchor other structural items. The channel's legs make it self-centering on the round column section, and the channel may be made as wide and as long as necessary to provide for...
nicholi,
Splice points are usually placed where the moment is least, to simplify the cost of the connection. For simply-supported, pin-connected members, this would be at the ends. As this is no help for splicing to extend length, simply move far enough back from the end of the beam to the...
Pylko,
It often helps to prevent cracking after drilling by chamfering the ID of the hole at the top and bottom with a 45-degree chamfering bit. This is especially helpful under loaded washers and nuts.
David
V23,
The gypsum roofs I have worked on were poured on steel bulb tees welded at their base flanges to the roof beams or trusses. The bulb tees had gypsum board or plywood board spanning between them and resting on the upper surface of the base flanges. The plastic gypsum was then poured on top...
steve111,
We here at NASA/MSFC recently went through some hoops about this subject. We finally decided that the suspect anchors were more easily replaced with new and trustworthy anchors than tested and "certified." The existing ones were often corroded, and their capacities were...
Hey there!
I hope someone out there can shed some light on this one: is there a simple ("quick & dirty") way to account for floor diaphragm stiffness when computer modelling a multi-story building? I have a concrete slab on standard bar joists, but that seems awfully time-consuming to...
IJR,
An old-time solution used under the support saddles (pads) of horizontal storage tanks (which move thermally) is to trap the base plate against welded guide angles in one direction. The base plate rests on a fixed steel liner plate, with a liberal amount of grease between the two to promote...
