dcStrucEng
Structural
- Feb 26, 2009
- 45
I'd like to solicit some opinions/advice for how other have dealt with the following situation. When working on projects that involve the renovation of existing concrete buildings, how have you all handled the specification and installation of new hangers to support MEP equipment? On projects where I've detailed post-installed anchors that are meant to support significant shear, tension, and/or moment, I typically include a note on my drawings (or in the specs) that require that the location of the in-situ reinforcing steel be determined (via GPR, x-ray, etc.) to avoid the contractor from blindly drilling and hitting bars.
But should this requirement extend to new MEP hangers installed in the slab soffit? Many times these are overlooked and not even mentioned in the structural drawings/specs. I'm not as concerned with the hangers having the capacity to support the loads (although this is important) as I am about the GC/sub drilling multiple holes close to each other until they get the depth required and this becoming a location for the propagation of cracks. Unless shallow depth drop-in anchors are specifically specified, I've found that most subs just use regular depth drop-ins that have lengths greater than the typical 0.75-inch concrete cover.
Opinions?
But should this requirement extend to new MEP hangers installed in the slab soffit? Many times these are overlooked and not even mentioned in the structural drawings/specs. I'm not as concerned with the hangers having the capacity to support the loads (although this is important) as I am about the GC/sub drilling multiple holes close to each other until they get the depth required and this becoming a location for the propagation of cracks. Unless shallow depth drop-in anchors are specifically specified, I've found that most subs just use regular depth drop-ins that have lengths greater than the typical 0.75-inch concrete cover.
Opinions?
