Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Demolition of Composite Floor Slab

Status
Not open for further replies.
LoneStarEngineer

LoneStarEngineer

Structural
Joined
May 4, 2016
Messages
37
Location
US
I am working on a demolition and replacement of a concrete slab w/deck for a composite floor system. We are essentially removing the concrete slab along with the deck and all the shear studs.
We will be shoring and reusing the steel beams which will be installed with new studs and new concrete slab w/deck. The largest bays contain 40 foot long girders with beams spaced at 8' o.c.

Some of the concerns that I wanted to discuss with the community are:

1. Pneumatic breakers/Jack hammers are proposed to be used for the demolition of the slab. How would the vibration caused by these effect the steel framing and the connections? As per the cut sheet the lowest vibration level for one of these machines is 6.2 m/s2 with a weight of 96 lbs.

2. If Jackhammers are not recommended for demolition of composite floor system, then what is the best way for demolition without adversely affecting the structural integrity of the steel framing systems.

3. Any suggestions for the demolition analysis of the existing steel framing system?

I have been researching on these topics and have not found much information discussing these issues. I hope this post can lead to some useful contributions for a better understanding of demolition of composite floor systems. Please include any/all useful information from experience or from any publications that you might have come across.

Thank you.
 
Sort by date Sort by votes
I've never used it, but "hydrodemolition" is effective in removing concrete without vibration: Hydrodemolition

As a bridge contractor in the 1970's we used pneumatic tools to remove portions of bridge decks to allow widening of the roadway. Some of the existing bridges had steel beam supported superstructure. Bridge widening has been preformed this way for a long, long time. Did not encounter, or hear of any problems with vibration damaging the steel to be reused. However, both the large mass and substantial structural bracing of a bridge is likely to make it more resistant to vibration damage than a building.

[idea]
[r2d2]
 
Upvote 0 Downvote
For bridges, my company directs the use of large excavator mounted hydraulic hammers all the time. But as SRE points out, bridge stringers may be more substantial than the steel framing you're talking about. Make sure to do a sanity check based on web and flange thicknesses.

With a relatively experienced demolition subcontractor and a properly sized hammer, you shouldn't have problems with hammering the deck off. Sometimes an inexperienced operator will get aggressive and bend up the flanges. Depending on the composite connectors, you may have to make a pass with heavier equipment to break out most of the deck and then go back with a lighter touch to clean out the embedded portions.

#3 is a little vague. What aspects of demolition analysis were you hoping to understand better?
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

SHEAR_FORCE
  • Question Question
Sistering to Undersized TJI Floor Joists
Replies
6
Views
8K
SHEAR_FORCE
SHEAR_FORCE
L
  • Locked
  • Question Question
What is the best strategy for shoring a structure during the partial demolition of a load-bearing wall in a renovation project?
Replies
3
Views
5K
Laura_mr
L
fchris82
  • Locked
  • Question Question
Timber floor joists reinforcement
Replies
2
Views
2K
fchris82
fchris82
MacGruber22
  • Locked
  • Question Question
PT Slab Edge Protection During Controlled Demolition
Replies
13
Views
1K
dik
dik
E
  • Locked
  • Question Question
Existing Suspended Slab Rectifications
Replies
0
Views
1K
engoaus
E

Part and Inventory Search

Sponsor

Back
Top