I work for a firm with a small structural department (4 structural engineers and one drafter). We also have similarly small civil, electrical, and construction management departments. Everyone in the company is not happy with the fact that no one has had a raise in 5 years and no kind of bonus...
amec2004 -
Thanks for the awesome posts! I can't thank you enough. I know you spent a ton of your personal time on this and I appreciate it. I will spend all day tomorrow studying and digesting all the info you provided before I hit the office on Monday. Rest assured your time has not been...
Can anyone point me in the direction of some good references for designing circular foundations. I am interested in learning the proper way to calculate bearing pressures due to overturning moments and detailing radial reinforcement. The foundations would be for use with things like water tanks...
The IBC in Ch 18 Table 1806.2 gives a "presumptive" value of 1500 psf (71.82 kPa) for clay. Also, Table 3-1 in TM 5-818-1 (US Army Corps of Engineers) gives a worst case value of 1400 psf for cohesion for clay soils. By definition, cohesion is 1/2 the unconfined compressive strength (qu), so...
Do you have a soils report? You might be able to just excavate the top two or three feet and backfill/compact with structural base course and top it off with a a sand cushion (if it's ok with the geotech), or a similar scheme. Ring walls are intended for use where you have crappy soil at the...
Hi Everyone,
I am working on a project that requires a significant amount of micropiles. It is a 150' long retaining wall with about 24' of retained soil and large lateral seismic loads and traffic loads. The geotech has specified micropiles for the project, noting that for lateral resistance...
Does anybody ever use the load combos in ACI App C for strength design? I never give them a second thought, but today while working on a footing design I used Enercalc (an older version) to check my hand calcs and the output showed that the program uses App C. Then I pulled out an old college...
There is no overturning. The only way that thing is going to overturn around the point of consideration is if the left side of the footing magically lifts itself off the ground.
This is a bearing pressure issue: P/A + M/S.
IBC 06, 3403.2, says "Additions or alterations to an existing structure shall not increase the force in any structural element by more than 5 percent..." That includes lateral resisting systems.
3403.1 says "Portions of the structure not altered and not affected by the alteration are not...
Wouldn't you have to jack up the existing footing to relieve the existing stresses? What if the existing footing is heavily stressed; the extension will be unstressed at construction before loading while the existing portion is already stressed. How do you deal with that?
Just thinking out loud...
No disrespect intended, but your original questions and follow up responses don't make any sense. And your questions regarding application of the lane live load is very basic. I would recommend that you consult with your senior engineer because it sounds like you are getting yourself, and...
Hi everyone,
When cofferdams or some other kind of stream flow diversion is required for bridge foundation retrofitting, are they designed by the engineer of record and shown on the contract drawings or are they designed by the Contractor (or his specialty engineer) like would be the case with...
Regarding the 180 deg hook and 6" embedment -- yeah I thought about that too...still thinking about it.
Regarding the reinforcing strips -- great idea, I will definitely look into that!
Thanks for the insight.
Hi hokie66,
The wall will be thickened on the tension face. We need to excavate to retrofit the footing, so that will be a perfect time to retrofit the tension face of the wall. Can't use soil nails because the exposed face of the wall is right up to the property line, and the adjacent property...
Hi everyone.
I'm working on a concrete retaining wall that needs to have its original flexural capacity almost doubled do to a change in use. The wall is about 13 feet high and currently supports an unused field overgrown with weeds and has been there for about 65 years. The land has been sold...
Sounds like a coordination issue between the architect and the PEMB guys. PEMB suppliers have a responsibility to coordinate their work with the architectural and MEP designers, just as the SE does on a "regular" building. After all is said and done, either the PEMB design can be modified or it...
Rowingengineer/Qshake -
Thanks so much. It makes so much sense now. Looks like we will need to retrofit the foundation by adding concrete drilled shafts and extending the pile cap. Looks like we will be using 20' deep (preliminary estimate) 2-foot diameter shafts most likely with casing.
Is...
Hi all,
I am analyzing an existing 75 year old bridge for a seismic retrofit. It is a 4 span bridge with concrete superstructure and concrete pier walls on concrete caps and timber piles. When checking the axial capacity of the piles (for both gravity and seismic), several people have told me...
