steel joist damage

Question

steel joist damage

kkerr (Civil/Environmental)

(OP)

27 Jul 04 09:39

Does any body know of any resources for evaluating damage to open web steel joist (bar joist)? I am evaluating one that got hit perpendicular to the bottom chord with a highlift. The bottom web was displaced so much it crippled the cross bracing. The bottom flange came back to about 1' displacement from the plane of the web. But I need to research how much this may have lowered the tensial capacity of the bottom chord. My original thoughts are to obviously replace any damaged cross bracing and bolt a steel plate to the bottom chord to repair the tensial strength of the damaged area. The top chord and web members appear undamaged. If anyone has any thoughts I would appreciate it. Thanks

Ron (Structural) · Answer 1 · 2004-07-27 22:30:23

With that much deformation, you need to check ALL weld connections as they might have been cracked. Check the connections of the joist bearing and the connections in the joist itself. Since the bottom chord had been plastically deformed, you should consider replacing. If impractical to replace, do significant strengthening to correct the deficiency. Make sure the joist is pulled back into place and is plumb. Remove all sweep and restore lateral bracing.

kkerr (Civil/Environmental) · Answer 2 · 2004-07-28 08:02:31

Thanks for the suggestions. We are planning on bolting plate to the bottom chord to restore tensial strength and are scheduling a lift to examine all the welds and connections and label the members so the repair crews know what to do to what member. Thanks again

jike (Structural) · Answer 3 · 2004-08-05 17:24:38

I strongly suggest replacing the joist. It sounds damaged beyond the point where it is repairable.

You can specify a new joist with either a splice at mid-span or one bearing end left off to be added on in the field. This will allow enough room for the erector put it up. A fabricator can combine this order for one joist with another job.

Make sure that the joist supplier designs this new joist as laterally unsupported between bridging lines or provide a special detail to continuously laterally brace the joist against the deck.

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steel joist damage