Bolt capacity in hand-tightened condition

[bugbus]

Are there any situations in which hand-tightened bolts (less than snug tight, basically loose) can be relied on for structural capacity?

I am checking a steel-composite structure which is intended to be continuous for the future live loading. The beams are initially to be installed in a simply-supported arrangement, then a series of splice plates will be (loosely) installed, and finally a continuous concrete deck cast on top. The splice bolts would then be fully tensioned after the deck has been cast and cured, and the beams have taken up most of the deflection due to the wet concrete. The intention of installing the splice plates loosely is to prevent any unintended continuity of the girders until after the deck is cast and cured.

My question is whether the bolts can be relied on for structural capacity in this hand-tightened condition? We may end up needing to rely on them in the temporary case to provide restraint to the beams during construction.

Thanks in advance

 

[desertfox]

Hi bugbus

My comment about friction relates to the slippage of the girders in that how one would oversize the bolt holes without considering the friction generated with the bolts hand tightened.
Also when the girders slip they will do so until the are stopped physically by the edge of the bolt hole hitting the bolt and that is likely to happen before the concrete can set, so unless I misunderstood the concept you are attempting doesn’t the girder slipping till it hits the bolt defeat the object?

 

[desertfox]

desertfox​

Mechanical​

Dec 28, 20025,549
Hi bugbus

My comment about friction relates to the slippage of the girders in that how one would oversize the bolt holes without considering the friction generated with the bolts hand tightened.
Also when the girders slip they will do so until the are stopped physically by the edge of the bolt hole hitting the bolt and that is likely to happen before the concrete can set, so unless I misunderstood the concept you are attempting doesn’t the girder slipping till it hits the bolt defeat the object?