Design of Huge RCB End Section
Design of Huge RCB End Section
(OP)
One of my coworkers dropped a Plan & Elevation on my desk of an RCB with some very custom end sections. I haven't ever seen anything like this before, but essentially the downstream end section has an 11' drop from the barrel to the apron, and the apron flowline is 3' or 4' below the existing channel flowline. The RCB barrel is 8' tall, so the wing will be about 20' tall at the barrel and slope down to about 5' or 6' at the end.
I'm sure terms vary depending on where you live, but what I call an end section is the wing walls and apron. Usually the apron runs the full length of the wings (and in between) and also acts as the footing for the wings.
I plan to analyze the the wings and apron as a U shaped concrete frame in the same way I would analyze an RCB as a rigid frame. This image from MODOT shows how I would apply the loads to an RCB. http://epg.modot.org/index.php?title=Image:751.8.2...
My concern is how to apply the distributed load acting upwards against the bottom of the apron. Obviously I won't have any live load and will have the self weight of the wings and apron for DC2. I am not sure how to define the load applied to the bottom of the apron due to the earth pressure on the wings. I do it all the time for retaining walls, but this thing is double sided and that is throwing me off.
I'm sure terms vary depending on where you live, but what I call an end section is the wing walls and apron. Usually the apron runs the full length of the wings (and in between) and also acts as the footing for the wings.
I plan to analyze the the wings and apron as a U shaped concrete frame in the same way I would analyze an RCB as a rigid frame. This image from MODOT shows how I would apply the loads to an RCB. http://epg.modot.org/index.php?title=Image:751.8.2...
My concern is how to apply the distributed load acting upwards against the bottom of the apron. Obviously I won't have any live load and will have the self weight of the wings and apron for DC2. I am not sure how to define the load applied to the bottom of the apron due to the earth pressure on the wings. I do it all the time for retaining walls, but this thing is double sided and that is throwing me off.





RE: Design of Huge RCB End Section
The ODOT standards were designed as an L shaped retaining wall and the toe length is iterated to satisfy a bearing pressure of 2ksf.
RE: Design of Huge RCB End Section
If you're doing this as precast then you have even more weirdness as you'll likely have a shiplap joint in the apron which you could argue will transfer shear across the joint for one apron/wing wall but will not transfer shear for the other side.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
www.americanconcrete.com
RE: Design of Huge RCB End Section
RE: Design of Huge RCB End Section
I like TehMightyEngineers's approach and have been wanting to do it so I can reduce a lot of reinf steel in those things. I'm just not fully proficient in being able to do the FEA. I've also spent the time and have a library that has reinforcing and concrete details for walls up to 20+ feet. I got extremely tired of designing and detailing them so now my techs know to go find the library.