Introduction

The handling and transportation of large loads is one of the critical points in various areas of industry. One of the assets used to move large and/or massive products is the overhead crane. This equipment provides great ease of use, safety for the workers involved and considerable time savings when carrying out this handling. With this in mind, it is possible to conclude that these machines are indispensable in industrial contexts. [1]

Cranes can often be seen installed on the roofs of industrial warehouses. The main components of this equipment are the girders, the trolley and the hoist or winch and their functions are described below.

• Beams: structure through which the car will move;
• Trolley: mobile equipment responsible for the transverse movement of the load;
• Hoist or winch: equipment responsible for lifting and lowering the load.

Check out this article on the work carried out by the Kot team on the structural analysis of a shed extension, with the aim of extending the runway of an overhead crane!

Structural analysis

A mining company wanted to increase the length of the track from axis 8 to axis 11 (Figure 1) on one of its cranes. To do this, it asked Kot to carry out a structural assessment of the shed in which the asset was installed, in order to make sure that the structure would support the change. 

For a better contextualization, here are some definitions adopted for the analysis.

• Utilization index (UI): Evaluates the degree of stress to which a structural element is being subjected;
• Permissible utilization index: Value defined in the standard for approving or disapproving the UI found.

The work began with the modeling of the metal structure in finite elements using the PROCAL 3D software developed by Kot. During modeling, the materials in which the structure is built were taken into account. Figure 1 shows the finite element of the shed where the crane is installed.

Figure 1: Finite element model of the shed - Axes. [2]

After modeling the structure in question in finite elements, the acting loads were studied and applied to the model. Some of the loads considered are listed below.

• Self-weight: These correspond to the forces due to the mass of all the fixed or mobile components of the shed, as well as mechanical and electrical components and support structures;
• Wind load: This load case deals with the wind load that the structure is subjected to. The forces are calculated based on the characteristics presented in the standard;
• Crane load: Corresponds to the load to which the structure is subjected as a result of the presence of cranes.

After defining and applying the loads, the structural simulation was carried out and the results can be seen in Figure 2.

Figure 2: Structural simulation of the shed [2].

Graph 1 shows in detail the utilization rates found compared to the permissible utilization rate.

Graph 1: Structure utilization rates. [2]

Connecting elements can be defined as those responsible for joining parts of the structure to each other or to external elements. Welds, screws, threaded rods and bolts are the main means of connection. In short, these elements can be classified into two groups:

• Flexible connection: No resistance to bending moments;
• Rigid connection: It presents total restriction to bending moments.

The work was followed by an analysis of the structure's existing connection elements and the results can be seen in Graph 2.

Graph 2: Link utilization rates. [2]

Conclusion

During the evaluation of the results obtained by the structural and connection analyses, no points of non-conformity were found, so the extension of the crane runway was approved and the mining company was able to proceed with its shed extension project.

Structural analysis is relevant to various areas of industry. With these studies, it is possible to accurately identify the existing loads and stresses on industrial assets and assess the structural behavior of the equipment in the face of these efforts. This makes it possible to pinpoint points where reinforcements may be needed. O Finite Element Method method is highly applicable, as it allows complex bodies to be analyzed with greater intuitiveness and ease compared to Numerical Methods.

One of Kot's specialties is structural simulations. The company is able to work in a variety of industrial contexts and has mastered knowledge of the assets present in companies. Contact our team for more information and quotes!

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References:

[1] What an overhead crane is and how it works. Kistler Morse, May 15, 2020. Available at: https://www.kistlermorse.com.br/post/o-que-%C3%A9-uma-ponte-rolante-e-como-funciona

[2] Kot Engenharia Collection.