= 24,192 lbs.
= 10 tons 16 cwt.
which is the safe load required.
To find the sectional area of a cylindrical beam square its diameter and multiply by ·7854.
The effect of fracture of a member of a scaffold depends upon its cause and upon the importance of the member destroyed.
If the fracture is caused by a live load, say a heavy stone being suddenly placed over a putlog, it is probable that the suspending rope, if still attached, would prevent more damage being done. If the fracture arose from an increasing dead load, say a stack of bricks being gradually built up by labourers, the mass would probably tear its way through all obstructions. Nevertheless, the entire scaffold, if well braced and strutted, should not come down, the damage remaining local.
The result of fracture of a standard under direct crushing would be somewhat different, as, providing that the scaffold is rigid, the greater strain thrown upon the ledgers, due to the increased distance between supports, would probably cause them to fracture. In this case the damage would probably still remain local. If, owing to the fracture, the effect of the bracing were lost, the whole scaffold would probably fail, as shown in the chapter on Stability.
It should be noted that the ledgers, together with the putlogs when fixed at both ends, apart from carrying the loads, have an important effect upon the standards, as, when securely connected, they divide the uprights into a series of short posts, thus dispelling any likelihood of failing by flexure.
CHAPTER X
THE PREVENTION OF ACCIDENTS
The safety of workmen depends not altogether upon the stability and strength of a scaffold, but also upon the use of certain precautions which, while not requisite for the progress of the work, are most necessary for the prevention of accidents.
