New to existing concrete beam connection
New to existing concrete beam connection
(OP)
Can this be done? We need to add new concrete beam to a coal unloading station. The beam will span 14' and will connect to an existing concrete beam and an existing concrete wall. The existing beam is 4' wide x 6' deep and the wall is 4' thick. The existing beam has ties at 6" oc, top and bottom bars, and face bars. The idea was to demo a beam seat into the existing beam and wall so that a bearing connection is obtained. The new beam is to support one train rail for coal unloading trains (Cooper 80 loading). Therefore, we didn't want to just dowel into the side of the existing beam and wall. Didn't know if it was feasible to chip out a beam seat...leaving the existing reinforcing intact and placing the new concrete beam.
Any better solutions using concrete? If not, might have to use steel and drop some columns.
Any better solutions using concrete? If not, might have to use steel and drop some columns.






RE: New to existing concrete beam connection
Mike McCann
McCann Engineering
RE: New to existing concrete beam connection
I would use steel if at all feasible. Any work with concrete would require a much larger outage time (read cost).
csd
RE: New to existing concrete beam connection
RE: New to existing concrete beam connection
I have actually removed hundreds of columns from the face of an existing, 6-story post-tensioned parking garage by doweling the old edge beam into the face of a new edge beam on the building expansion, and then sawcutting out every other existing column. Shear friction really works!
RE: New to existing concrete beam connection
if you are deciding to drill and dowel in bars, you need to take caution so that the existing bars in the concrete do not get damaged.
RE: New to existing concrete beam connection
RE: New to existing concrete beam connection
Check that the anchors are appropriate for vibrating loads, and that they are not in constant tension.
csd
RE: New to existing concrete beam connection
I believe that shear friction works but epoxy adhesives don't always work as advertised. Especially in constant tension.
RE: New to existing concrete beam connection
RE: New to existing concrete beam connection
- design new beam as simply supported
- use epoxy anchors, old / new concrete interface should be well roughened
- if vibration involved use Hilti HVU system or other equivalent system. Hilti HY 150 and RE 500 don't carry approval for vibration loads
- if beam is designed as fixed at both ends; there will be tension load applied on the anchors. Then the deformation of anchors under applied loading should be checked as excessive deformation might diminish the effective shear carrying capacity at the old / new concrete interface which had been roughened
Clefcon