Stress-strain state of a steel tower crane during erection by the pushing method

Introduction. Inclined shaft headframes are among the most critical types of surface mining structures. The duration of construction and assembly of these structures directly affects the overall efficiency of the enterprise. Therefore, investigating the changes in the stress-strain state of steel headframes during installation by the pushing method is particularly relevant today, as it can help reduce the construction time of these structures.

Aim. This study aims to analyze the influence of assembly loads on the stress-strain state of the tower metal headframe during the moment of pushing.

Materials and methods. A BIM model was created in the Tekla Structures software for information modeling in order to analyze the structural scheme of the construction with the installed equipment. This model provides a more accurate assessment of the mass of the structure. Numerical studies of the inclined headframe were conducted using domestic software and the LIRA-SAPR 2024 computational complex. The system under consideration is presented in a general form, with deformations and main unknowns represented by linear displacements of nodal points along the X, Y, and Z axes, as well as rotations around these axes.

Results. An analysis was performed to determine the loads and influences applied to the structure while it was being pushed. The actual behavior of the structural elements was taken into account. The headframe is 85 meters high and has a total mass of 8,028 tons. A mathematical model of a two-bracing skip-cage headframe was developed to assess the influence of installing the structure by the pushing method. Considering the sliding friction coefficient, five jacks with a capacity of 1,000 tons each were selected for installation. The jacks are installed on the axes with the greatest load on the rolling path. The obtained results enable the selection of equipment for the pushing operation.

Conclusions. The calculation revealed that the retention coefficient is 13.06 in the direction of the tower headframe pushing, meeting the requirements for overturning resistance. Analysis of the stress-strain changes in the skip-cage headframe during installation using the pushing method revealed the need for five 1,000 ton hydraulic jacks. Adjusting the jack pressures on each axis prevents rotation of the entire structure and subsequent jamming of the pushing stand. Moreover, when these structures are being pushed, it is essential to remove the bracing that is perpendicular to the movement of the headframe. This will result in a reduction of the number of rolling path axes.

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