Box Girder Crane Designs
Designing a box girder for a crane is a complex process that involves several steps and considerations. KTM Engineering has been designing box girders for well over a decade with more than a hundred designs in use around the nation. KTM designs box girders in accordance with CMAA standards.
The Design Process
Here is a general overview of the steps involved in designing a box girder for a crane:
Define the requirements: The first step in designing a box girder is to define the requirements. This includes the span, building constraints, operating parameters, and load conditions that the crane will be subjected to. The load conditions include the maximum weight that the crane will be required to lift with various static and dynamic factors applied.
Calculate the size/geometry: Utilizing the general size guidelines in the CMAA standards, the size of the various components is determined. The basic construction of a box girder involves flange plates (top and bottom) and web plates (sides). The overall size and thickness of these components must be determined. Other geometry includes stiffening members and end connection components.
Perform structural analysis: The requirements are used in conjunction with the CMAA requirements to validate the selected size of the box geometry. This includes strength, fatigue, deflection, and stability calculations. All members as well as any bolted or welded joints must be checked for sufficiency.
Optimize the design: Based on the results of the structural analysis, the design of the box girder should be optimized to ensure that it can withstand applicable loads while minimizing the weight and cost of the structure.
Drawing creation: Once the final sizing has been determined, the fabrication drawing package can be created. Utilizing both 3D and 2D CAD, all components are detailed to prepare for material order and assembly.
Fabrication and inspection: After the design is finalized, the box girder can be fabricated. Before installation, inspections of the fabrication process and the final product including load testing are crucial.
Working from Experience
It's worth noting that this is a high-level summary of the process and there are many more details and specific standards that must be taken into account to design a box girder for a crane. It's advisable to work with an experienced engineer and follow the regulations of the industry and country where the crane will be operating.