The boom of a hydraulic crane was bent while removing temporary sheet piles at a construction site. A vibratory hammer had been placed at the top of the sheet piles to both drive and remove the piles. The vibratory pile driving placed no significant loads on the crane boom, as that operation relied on the weight of the sheet piles and the vibration of the hammer to sink the piles into the soil. The vibration of the hammer and the lifting force of the crane boom were needed to remove the sheet piles from the soil.
When removing steel sheet piles, there is often a temptation for the crane operator to use the crane boom to shift the sheet pile from side to side to help free it from the soil although side loads ideally should never be placed on a crane boom. In this case, the crane operator was removing sheet piles and improperly placed a side load on the crane boom while shifting the sheet pile to one side and bent the boom.
The crane manufacturer had approved the crane for pile driving and removal operations even though the crane boom had very little capacity for side loading in comparison to other types of cranes. It should however, be anticipated that the boom would be subject to impact and side loading during pile driving and removal.
Although the crane operator was initially determined to be at fault for bending the boom, a post loss engineering evaluation determined that the boom was minimally capable of pile driving operations under ideal conditions. Therefore, the crane manufacturer marketed the crane for a purpose for which it was not well suited. Additionally, the crane manufacturer suggested replacement of the entire boom at significant cost and loss of use. However, a forensic engineering evaluation determined that the boom was repairable and identified multiple facilities that could repair the boom, warranty the repair, and reduce the down time for the crane at a cost that was much less than the manufacturer’s suggested repair cost and time.
John Phillips, senior consulting engineer at Warren, has more than 30 years of crane and heavy equipment experience and more than 17 years of experience in forensic engineering. A licensed professional engineer in South Carolina, North Carolina, Georgia, Louisiana and Ohio, he’s NCEES registered both as a model engineer and with The United States Council for International Engineering Practice, USCIEP. John has designed crane systems, supervised installation, tested and certified lifting equipment even serving as a project engineer for maintenance and certification of nuclear weapon lifting and handling systems. John is a certified fire and explosion investigator and fire and explosion investigator instructor by the National Association of Fire Investigators. John is a member of the American Society of Materials and American Society of Testing and Materials, as well as a voting member of ASTM Ships & Marine Forensic Sciences, Forensic Engineering, and Performance of Buildings committees.