Like most things in life, lifting operations are only successful when they are supported on a firm foundation. We know that around 13% of crane stability failures are related to ground or loadspreading problems. Contributory factors to this statistic include proximity to voids and trenches, weak foundations/soil and poor loadspreading mat arrangements. Proper soil preparation is vital, albeit environmental factors such as rain or the thaw in Spring can have a marked influence on the ground’s loading capacity.
REQUIREMENTS AND RESPONSIBILITIES
During an inquiry into a crane overturning incident, it was reported that “the accident was caused by the failure to use metal spreader plates under the crane, and the reliance on timber loadspreading following a week of rain”. In the USA OSHA 1926.1402 requires that “equipment must not be used unless ground conditions are firm, drained and graded so that with the use of supporting materials the equipment manufacturer’s specifications for adequate support and degree of level are met”. Moreover OSHA regulations state that the legal entity with overall responsibility for the construction is responsible for ground conditions – a requirement backed up in the standard terms offered by most equipment suppliers. This usually holds the site owner or general contractor responsible.
LOWTHER-ROLTON PROVIDES A FIRM FOOTING
L-R regularly prepare original ground bearing calculations, or undertake independent third party Technical Audit of calculations prepared by others. We use specialized software to calculate the crawler or outrigger loads generated by the machinery, and then analyze the effectiveness of the loadspreading system. Our structural engineers ensure that the supports are not overstressed and are effective to meet the maximum allowable pressure requirement. Crucially we analyze all phases of the lifting cycle, knowing that the highest pressures may be developed in a “no load on the hook” condition. Working on Wind Farm projects, we have also optimized the matting requirements for travel between lift positions. Lowther-Rolton’s responsive team of experts are ready to assist Project Owners, EPC Contractors and equipment suppliers. Whether you are in the planning phase and determining ground improvement schemes, or ready to lift a load and need immediate assistance we are here to help. Call us on +1-832-702-3342 to chat about your Project.
Lowther-Rolton is the premier independent engineering consultancy for Heavy Lift & Construction Engineering, providing original in-house design and third party verification services.