Design analysis of the reinforcement on the foundation

MacGREGOR (SWE) AB (Crane Division) is located in Örnsköldsvik and provides cranes handling cargo on ships and in ports with capacities ranging from 3- 500 tonnes. When MacGREGOR (SWE) AB (Crane Division) sells a crane the design must be approved by a classification society. One of the classification societies did not approve the design on one of the foundation types MacGREGOR (SWE) AB (Crane Division) uses. The reinforcements used today are designed and implemented by demands from the classification society Germanischer Lloyd. The problem with these reinforcements is the design, which increases the manufacturing time and cost. Therefore the purpose with this thesis is to analyze the current design, examine the need of the reinforcements and if necessary design a new reinforcement. At the beginning of the project focus was on gathering information about how and why the reinforcements are used today. Unfortunately there has been no opportunity to have contact with the reinforcement designer Germanischer Lloyd. Instead the knowledge about the reinforcement, how and why they exist, come from interviews with well-informed personnel at MacGREGOR (SWE) AB (Crane Division). To investigate how the reinforcements affect the stress distribution on the foundation, a simplified model of the whole crane with bearing, crane house and crane arm was modeled. Finite element analyses in I-deas were performed on the model with eight node sheet elements. The result from the first simulations showed that the reinforcements were unnecessary. These simulations led the thesis into further analyses instead of designing a new reinforcement. Further analyses show that the reinforcement lowers the stress in the foundation at the worst places with ≈ 12 %. The result led to analyses with different thicknesses of both the foundations sheet case and also the reinforcement ring. By having a thicker plates in the sheet case of the foundation the stress lowers in a satisfying way, but the total weight and the material cost increases. By increasing the thickness of the reinforcement ring the stress decreases and a safety margin of 1.5 can be retained. The increase in material cost that a thicker reinforcement ring results in is lower than the cost of the stiff plates that are used today.Validerat; 20101217 (root