What is the overall deflection as it stands? Actual load distribution can differ widely from the theoretical maximum, and live loading is almost always considerably less than that prescribed. Plus both loadings will have been factored. I'm not saying it's right, just that the actual situation may not be as bad as it theoretically seems. In fact it might be perfectly ok.
Structural engineer missed point load - advice please
- Thread starter Daniel Johnstone
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Late to the party here but I agree with Tony. I'd never design a pair of beams supporting separate leaves as acting together. Not by using tubular spacers anyway.
I usually limit dead and live load deflection to span / 360 where carrying existing masonry, as limiting dead load deflection limits the risk of initial cracking when the props are removed and the beam is loaded up.
Span / 280 for dead and imposed load is within the recommended limit of span / 250. If you don't have any cracking in the masonry now it's unlikely any will appear when the small amount of live load is added.
Also, it's likely the loads onto both Beam 1 and Beam 2 can be reduced.
The imposed roof load can be reduced in line with the pitch of the roof (the steeper the pitch the less live load needs to be taken.
There are likely windows in the supported elevations which won't have been allowed for in the calcs, allowing perhaps a 20% reduction in the weight of the masonry.
Would be interesting to see the whole layout of the proposals.
I usually limit dead and live load deflection to span / 360 where carrying existing masonry, as limiting dead load deflection limits the risk of initial cracking when the props are removed and the beam is loaded up.
Span / 280 for dead and imposed load is within the recommended limit of span / 250. If you don't have any cracking in the masonry now it's unlikely any will appear when the small amount of live load is added.
Also, it's likely the loads onto both Beam 1 and Beam 2 can be reduced.
The imposed roof load can be reduced in line with the pitch of the roof (the steeper the pitch the less live load needs to be taken.
There are likely windows in the supported elevations which won't have been allowed for in the calcs, allowing perhaps a 20% reduction in the weight of the masonry.
Would be interesting to see the whole layout of the proposals.
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@RonnyRaygun, never too late buddy. No probs, calcs are attached.
@jeds, just waiting on someone to calculate current overall deflection. Will let you know soon.
@jeds, just waiting on someone to calculate current overall deflection. Will let you know soon.
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Hello Daniel, just wondering how things are progressing with your project.
I agree with the others, span has been always L/360; the safety factors should help but bear in mind that the deflection normally is calculated with unfractured loads, so it may be a buffer there.
The solution may be welded plates to increase the rigidity of the beams 2.
Looking at the picture you posted, do you know how much the beams 1 extends above the Beams 2 - that may be the reason why he is assuming a shear load, because the beams are extending to the two beams and not just resting on the one on the inner leaf of the cavity wall.
Just a though.
I agree with the others, span has been always L/360; the safety factors should help but bear in mind that the deflection normally is calculated with unfractured loads, so it may be a buffer there.
The solution may be welded plates to increase the rigidity of the beams 2.
Looking at the picture you posted, do you know how much the beams 1 extends above the Beams 2 - that may be the reason why he is assuming a shear load, because the beams are extending to the two beams and not just resting on the one on the inner leaf of the cavity wall.
Just a though.
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