Top of Wall/Bottom of Wall 2

[GoldDredger]

I have a project where a fair section of concrete retaining wall as high as 5 feet will be constructed.

On my plans I have provided spot shots of top of wall and bottom of wall, which are defined the finished (landscape) grades either side of the wall.

My detail of the wall establishes the schedule of rft, dimmension and thicknesses depending on height. It also sets minimum dimmensions of finished grades above footing and below top.

Along this wall, the finished landscape grades will vary. From a materials standpoint, the footer of the wall could probably be raised or lowered depending on location. (As oppposed to one constant footer elevation across the entire lenght of the wall)

Question, do you think the Civil should call out the footer elevations and establish break points. Or should that be left to the contractor to meet the minimum dimmensions of the detail, and choose is own means and methods of constructing it?

Thanks

 

[bimr]

It depends. If the project is located in northern regions, the footer should be below frost depth. You may also have to consider the overturning moment on the wall if you are retaining something.

 

[Ussuri]

Surely your design and calculations for wall stability will be dependent on the levels at which the footings are to be constructed. In which case it is related to the design, in which case I would think you should specify it.

The majority of contractors I work with would not accept the liability of detailing something which is permanent works, especially if there is a designer on board.

There are expections to this however, such as design and build contracts, where it would be quicker to have a footing at one level (easier shuttering and pouring) and use more material if it means earlier completion.

 

[gerhardl]

I think your question is split in two, and requires two answers:

a) The design answers is yours, and minimum requirements and limitations for all necessary constructional details should either be given on the drawing, or as additional text on the drawing.

b) The 'free' grade to adapt the drawing to the actual underground /aboveground details could be opened by for instance something like (additional text): adaption allowed as long as minimum requirements is satisfied. Must be documented and countersigned/approved by designing company. EG. still designing responsibility clearly defined as yours.

 

[civilperson]

Every dimension and change of elevation MUST be shown or you should not be paid for designing the wall.

 

[bob3306]

It does depend on your contract. I specifically exclude the design of any retaining walls over 3' or that supports any sort of load. Jurisdictions vary, but most have a maximum height above which structural calcs are required. I do show spot elevations and the "geometrics" as you did, but I add a note that says "The Contractor shall provide shop drawings and design calculations sealed by a Profession Engineer licensed in the state of blah blah....". I still may call out a "Segmental Block retaining" of a particular color, block size or manufacturer, but leave the reinforcement design to others.

Most block manufactures are more then happy to have staff engineers design and seal the plans for the contractor.

I few times I've seen the buildings structural engineer design them.

If I had to do it under my contract, I would sub it out to a geotech or structural with more experience then me to do it.

 

[GoldDredger]

Thank you all for the responses.

bob3306, we are definately on the same page. I excluded the design of retaining walls in my scope just so you know. I provided a 'beefy' retaining wall detail for the bid set for pricing.

On this detail, I indicate contractor may construct modular retaining wall, however must submit 'engineer stamped drawings for review and approval'

I've already recieved some additional services for a hickup between owner and architect. In this particular case, seeking an additional on the retaining wall will just generate some ill will. I'd get the $3-4k for additional service, but they probably wouldn't hire me for the next job. (The goose that lays the golden egg) That is a reality of being a consultant.

I think Civilperson is right though. If you are going to design the wall, I'll need to include all the information. Namely top of footer along with break locations and grades.

Thanks Again.