Crane Boom Loadings from Pile Driving-PDF

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Pile-driving operations increasingly use longer, heavier piles and more powerful hammers, placing greater and more varied loads on crane booms. Unlike swinging leads, which generally apply vertical loads and cushion driving shocks through cable support, fixed and semifixed leads also impose side loads and standing moments. Fixed leads transmit shocks directly to the boom; semifixed leads dampen them.<br /><br />For fore-and-aft batter, operators should calculate an equivalent vertical load, WE, that produces the same moment about the crane’s rotation center as the pile-driving equipment. Compare WE with the crane’s rated capacity, WL, at the operating radius. Check the plumb setup first, then fore batter with the hammer and drive cap at the bottom of the leads, and aft batter with them at the top and the pile clear of the ground. If the crane will travel while carrying the lead, use a more conservative capacity allowance. Reduce the load or operating radius if capacity is exceeded.<br /><br />A semifixed lead resting on the ground can transfer vertical load to the ground, leaving the crane to carry lateral load and perform hoisting. This may increase effective capacity, but fore-batter setups require particular caution: a negative equivalent load can tend to rotate the boom backward.<br /><br />For side batter, assess the boom’s horizontal side load, its induced standing moment, and the vertical-load case. Check multiple hammer and pile positions, including the condition just as the pile touches the ground, which can produce maximum torque on the crane’s swing system. Engage the house lock before contact. Compare side load with the applicable allowable limit; the crane manufacturer must evaluate whether the boom can withstand the combined loads and stresses.<br /><br />Because boom failure under compression can be sudden, operators and contractors should calculate loads for every relevant boom position and batter angle, and obtain the manufacturer’s approval for structural capacity.
Keywords
pile-driving
crane boom loads
fixed leads
semifixed leads
fore-and-aft batter
side batter
equivalent vertical load
rated capacity
standing moment
boom structural capacity