Crane beam design example code#

Another means of preventing derailing is to have a stop tab that runs below the runway I-beam such that it limits uplift and prevents the crane from derailing. The end truck wheels typically have flanges on both sides to stay on the track. The flange local buckling due to the trolleysвЂ™ wheel load is reviewed and its stresses are added to the respective component stresses.ДЄnother important consideration is preventing the bridge from derailing, including the case of the trolley impacting its stops. Typically, the hoistsвЂ™ trolley deadweight and payload are combined to obtain a worst case bending stress on the bridge beam, which is typically located at the center of the bridge span. Structural Qualification: The stresses throughout the structure and at the connections are evaluated against limits. For outdoor cranes, wind loads can be a source of serious accidents, and the crane must be designed, operated and parked taking into account the wind loads. Horizontal impact loads account for the possibility of the trolley or the crane bridge running into their respective bumper stops. For this reason, variable speed hoists are advantageous since they start slowly and gradually increase their speed, therefore reducing the payload inertial effects. Hoists that fully or abruptly engage at the start of the lifting process increase the hoist payload from inertial effects by 50%. The payload is the maximum permitted pick load. Dead weight for a single girder bridge beam can be applied at the center of gravity. The loads applied to the crane bridge are normally deadweight, the payload (rated load), inertial effects due to motion, skewing loads, seismic, and, if outdoors, the wind loads. Designing the crane per CMAA-74, the number of cycles determines the service class and the life of the crane bridge. They include the crane rated load and the number of load cycles. CMAA-74 provides the design loads and criteria for the structural, mechanical and electrical crane components.Дesign Loads: Several structural factors must be addressed in the analysis and qualification of the crane bridge.

Crane beam design example code#

The scope of CMAA-74 points to supplementary design codes, such as the building code (ASCE-7), and crane maintenance standards (ASME B30.11, ASME B30.17). The scope of CMAA-74 covers the crane classification, structural design, mechanical design, and electrical equipment. CMAA is the Crane Manufacturers Association of America, and CMAA-74 is the Specification for Top Running and Under Running Single Girder Electric Traveling Cranes Utilizing Under Running Trolley Hoist. The CMAA Standard for Cranes: Becht Engineering recently completed the structural analysis for a single girder 5-ton crane bridge with an under-running hoist per CMAA-74 for nuclear waste handling operations.