Search results for query: *

LRFD is more time-consuming than the 16th or 17th Edition - which should be no surprise to anyone who has hefted the two documents! In concrete design, the biggest difference is shear-capacity calculations. All that work to get a crack angle and beta factor!

Isn't (2) awfully expensive? Since (1) is no longer being used for new designs, hopefully you should be able to borrow it. Do you know anyone who works either at a state Dept. of Transportation or a consulting company that does bridge design work? BRGENG - I think both (1) and (2) are LRFD...

kelowna, I couldn't make myself read all 21 pages of that article, sorry. I think I get the gist, though, and my perspective is that the public should get a nice-looking bridge if it's in a prominent, visible location where what it looks like really matters. I do notice, though, that when the...

Thanks - I laughed until I cried.

I am just starting to use SAP2000 for this, though I'm using version 11 (not 8). It seems OK, but the user has to input the hinge properties (CSI sells a different program, called CSiCOL, that is supposed to calculate the nonlinear behavior of a given RC section).

Hello, Qshake, Some of my columns are quite tall (86' clear height). I wanted to ensure double bending in both directions to keep KL reasonable, both so I wouldn't have to figure out how to combine nonlinear second-order P-delta analysis with elastic seismic analysis (AASHTO allows use of...

Thanks! This is only my 2nd serious attempt at strut-and-tie design (not counting a couple of really simple situations), and both times I find my thinking gets in a rut once I've come up with one that "works," and it gets hard to come up with a different one. With this structure I feel trapped...

Has anyone else done a strut-and-tie model for a concrete bridge crossbeam (bent cap) under earthquake loads? Did you use the results in your design of the reinforcing? If not, what did you use for the structural design of the crossbeam for seismic loads? The column joint-region design...

I have noticed that the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals (with interims through 2003; a new interim is supposed to be coming out soon) shows no welded pole-to-base-plate details that are in a higher fatigue category than E...

dgillette, I came through a little after you (class of 1985). Same profs, but as you can see I stayed with structures. Ended up in bridge design on the West Coast. UPDATE ON THE WALL: We ended up calling for the Contractor to build a temporary bench of soil up to the right elevation for...

BigH, thanks for your suggestion about deadman anchors. We will leave construction methods up to the Contractor, but I suspect he will be very likely to use deadmen for the earlier stages of the backfilling, because the horizontal forces at the early stages will be much smaller than the forces...

BigH, I agree with you about the tanks, plus if they're going to drive drunk it shouldn't be the taxpayers' problem, right? It seems likely to be cheaper to just add extra top-row tiebacks to the wall rather than to build a whole moment slab with tiedowns that crisscross with the wall...

PEinc, The geotech says the soils aren't dense enough for soil nails. So much for that idea. FYI, the barrier crash test levels in AASHTO LRFD go up to TL-6, which is a tank, and the horizontal design load for that is 175 kips!!! Take a look at Table A13.2-1 on page 13-17 of the AASHTO LRFD...

PEinc, I don't think a single tier would work for the taller portions of this wall, since we have to design for the new AASHTO LRFD traffic-barrier impact loading, in this case Test Level 4 (54 kips horizontal force at 2'-8" above roadway surface at top of wall). A temporary excavation-support...

Thanks to TDAA for a great idea. If soil nails would work, overall cost would be very reasonable, and I would sleep better at night knowing the project is unlikely to result in a construction disaster. My problem right now is that I am the checker and not the designer, so I'll need to sell the...

The wall will be installed at/near the toe of an existing roadway side slope, to widen the road. Maximum exposed wall height would be about 23 ft. The client would much prefer that the wall construction not interfere with existing traffic. The tiebacks would have to be re-stressed to the...

I know these walls are more usually built by excavating, but... Does anyone know how to analyze a wall like this for the temporary condition just prior to installation of the 3rd tieback, which is when the problem becomes indeterminate? I used the approach described in Braja M. Das's...