How to determine deflection of open web steel joists in-situ
How to determine deflection of open web steel joists in-situ
(OP)
I have a project where existing conform deck and concrete slab span over existing metal joists. The owner wants to have a deflection test after shelving is installed. I was thinking measure the current deflection with a high precision laser at 1/3 or 1/4 points as well as at the center. Document that the baseline is the same for all measurements, then come back after loading and measure defelction again.
This is not to verify that the load can be supported, that as already been deteremined through analysis. This owner just wants to have as much documentation as possible on the condition of the structure before and after loading.
This is not to verify that the load can be supported, that as already been deteremined through analysis. This owner just wants to have as much documentation as possible on the condition of the structure before and after loading.






RE: How to determine deflection of open web steel joists in-situ
zip level would work
good laser would work.
i'd consider doing the following:
1. calc expected deflection change, in order to get an idea of what to expect and thereby determine the accuracy of the laser you want. Home Depot varieties are likely not accurate enough.
2. considering the accuracy you want, precisely mark on the floor the positions at which you take the initial measurements, so as to be able to obtain comparable measurements post subsequent deflection.... helps you dodge issues with high and low spots on your base below your joists.
3. develop laser technique to make sure your aiming true vertical. I don't think this would be needed with zip level.
4. depending again on accuracies, i'd consider getting lots more data points, which takes not very much time, say at each bottom chord panel point.
5. consider that supporting girders will deflect too, if that is of interest to you.
6. if you're completely obsessive like me, you could get some relative changes between the top of your deck and the structure above, the increase of which would correspond to the decrease in elevation below the deck.
have fun!
RE: How to determine deflection of open web steel joists in-situ
RE: How to determine deflection of open web steel joists in-situ
RE: How to determine deflection of open web steel joists in-situ
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RE: How to determine deflection of open web steel joists in-situ
RE: How to determine deflection of open web steel joists in-situ
RE: How to determine deflection of open web steel joists in-situ
i'm drinking 805 beer atm,
what kind of scanner, and what kind of accuracy? I've been looking at these.....
RE: How to determine deflection of open web steel joists in-situ