Innovative Application and Design Key Points of Crane Girders Serving as Rigid Tie Rods in Light Steel Structures
Advantages of Integrating Crane Girders with Rigid Tie Rods
Light steel structures are widely used in the modern construction field due to their unique advantages. The ingenious integration of crane girders and rigid tie rods further enhances the performance of light steel structures. This design not only saves materials and reduces structural self-weight, but also effectively improves the overall stability of the structure. In large-scale industrial plants, warehouses and other places, this integrated application has become an indispensable building component. In the portal rigid frame light-weight building steel structures, crane girders can be used as an alternative to bear the function of rigid tie rods, but they must meet specific design requirements.
Design and Application Key Points
A. Requirements to be Satisfied in Crane Girder Design
a. The fire resistance rating of crane girders shall be consistent with that of inter-column bracings.
b. When calculating crane girders, the axial force borne by them as rigid tie rods shall be taken into account.
c. To prevent support problems caused by possible misalignment of joints, such as translation or torsion of supported components, additional angle braces shall be installed for correction.
d. The design of support joints must meet the relevant structural requirements for withstanding axial forces.
The design scheme of using crane girders as longitudinal rigid tie rods is not only economical, but also a desirable option due to the large cross-section and good rigidity of crane girders themselves. However, during the implementation process, the above key issues must be paid attention to, so as to ensure the rationality and safety of the design.
B. Key Measures for Crane Girders to Serve as Rigid Tie Rods
a. In light steel structures, the corbels of crane girders are usually designed as cantilever beams to utilize crane girders as rigid tie rods. For side columns, however, due to the certain distance between the crane girder and the column center, it can only provide lateral support for the inner flange of the column, but not for the outer flange. In addition, the longitudinal braking force and transverse horizontal force of the crane will generate lateral bending moments on the cantilever corbels, which in turn impose additional torsion on the columns. Therefore, to enhance the support effect, angle braces shall be arranged on the upper flange of the crane girder and connected to the outer flange of the column. It is necessary to ensure that both ends of each crane girder are equipped with angle braces to achieve bilateral support for the column.
b. For middle row columns with crane girders arranged on both sides, it is recommended to install bilateral angle braces on these columns to enhance the lateral stiffness of the crane girders. In this case, the angle braces may cross each other, but through ingenious design, the two crossing angle braces can be connected to the upper and lower surfaces of the upper flange of the crane girder respectively. Meanwhile, stiffeners shall be arranged on the columns to serve as connecting plates for the angle braces, and their thickness can be consistent with that of the crane girder flange to facilitate the connection of the angle braces.
c. If the crane girder of the end span is not designed as a cantilever structure, rigid tie rods must be arranged in the end span to ensure structural stability.
d. Special attention should be paid to the fact that crane girders are usually installed in the subsequent construction stage. When the crane girders are not installed during the construction period, corresponding measures must be taken to ensure structural stability. In addition, for plants with reserved crane positions or where crane girders are not installed for a long time, rigid tie rods should still be arranged to ensure the safety and stability of the structure.
