simple enough question.. on a drawing job it requires twin beams [450 hakis]. are you expected to stagger the joints on the beams between the pair on the back of the standards, with the pair on the front of the standards..[nightmare for your puncheons].. or are we allowed just to keep them all in a line opposite each other.. [chosen solution].. unfortunately the drawing does not show what is expected... the span is 11m... do we use all 6m beams , all in a line, or are we expected to stagger the joints with a 8m / 4m combo????
twin beams
- Thread starter g-scaff
- Start date
bigfish
Moderator
Ideally you'd use a 8m + 4m combo with the back staggered opposite to the front,but if the drawing does'nt show any joints then just use 6m beams throughout,after all the beam pins are tested to be strong enough
philliosmaximus
Moderator
i would just use 2 x 6 meter beams either side if it does not stipulate they should be staggered , like you say makes a real mess of the puncheons
thanks lads,.. thats what i wanted to hear,.. although too late for this job... i staggered them and regretted it the moment i tried putting puncheons on... never again and can i quote you 3 if ever things go wrong..:wondering::wondering
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I remember in the late 80's and early 90's working in London, the craze at the time was to fix a row of steel 4m unit beams to the inside of the standards just above the toeboards, then another row just above on the outside of the standards when bridging with a lot of lifts above. Don't know if this still goes on or not ?Never bothered staggering the joints in the beams as our designer told us it didn't matter.
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S
steveo south east
Guest
Just curious did you piggyback the beams?if yes does it say on drawing to piggyback
We have just finished a design job with 750 Layer beams and no mention of staggering joints ,and if you try biffo0911 points out the problems nicely
yeah we did, elevation shown shows them either side of the standard/puncheon, and also highlighed as "twin beams"
It's worth explaining why joints (in access scaffolds) are staggered.
In some cases it can be shown that there is tension present in the ledgers especially. Sleeves and spigots have limited capacity to resist tension....so it is good practice not to have all the joints in one line forming a "line of weakness". Theory being the tension across the joint will be transferred through the frame to the adjacent lift / bay which does not have a joint - because they are staggered.
Where the joints are capable of carrying tension, such as if they are lapped/spliced there is no requirement to stagger the joints. For example if we design a scaffold and decide the ledgers and/or standards require their joints to be lapped then there is no need to stagger those joints.
Beam joints support tension....so do not need to be staggered.
Simples!
In some cases it can be shown that there is tension present in the ledgers especially. Sleeves and spigots have limited capacity to resist tension....so it is good practice not to have all the joints in one line forming a "line of weakness". Theory being the tension across the joint will be transferred through the frame to the adjacent lift / bay which does not have a joint - because they are staggered.
Where the joints are capable of carrying tension, such as if they are lapped/spliced there is no requirement to stagger the joints. For example if we design a scaffold and decide the ledgers and/or standards require their joints to be lapped then there is no need to stagger those joints.
Beam joints support tension....so do not need to be staggered.
Simples!
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