Steel Structure Workshop—Design Features of Crane Beam

General cranes are widely used in indoor and outdoor steel warehouses, steel workshops, docks, and open storage yards. The crane is mainly composed of cart operating mechanism, trolley operating mechanism, hoisting mechanism, and electrical equipment. The two ends of the frame are supported on the elevated track above the workshop or open-air cargo yard through the running device and run longitudinally along the track. And the crane trolley runs horizontally along the trolley track on the main beam frame. Technology engineers need to take features of the crane beam into consideration during the steel structure designing.

Crane Beam Design

Generally, crane beams are simply supported (simple structure, convenient construction, insensitive to support settlement) with common forms of steel beams(1), combined I-beams(2), box beams(3), crane truss(4), etc.

Crane Beam Load

Permanent load (vertical).

The dynamic load has horizontal and horizontal directions and is characterized by repeated actions, which will cause fatigue damage easily. Therefore, the requirements for steel are relatively high. In addition to conventional requirements such as tensile strength, elongation, and yield point, it is also necessary to ensure that the impact toughness is qualified.

The Composition of Crane Beam Structure System

1.Crane beam

2.Braking beams or trusses

Crane Beam Load

The crane beam bears loads from three directions directly: vertical load (system weight and heavy goods), lateral horizontal load (brake force and rail clamping force) and longitudinal horizontal load (brake force). The longitudinal horizontal load won’t take into consideration during crane beam design.

Crane Load Calculation

The load code stipulates that the standard value of the horizontal crane load shall be the sum of the horizontal trolley’s G gravity and the rated lifting capacity’s Q gravity multiplied by the following percentages:

Soft hook crane: when Q≤100kN, take 20%

When Q=150～500kN, take 10%

When Q≥750kN, take 8%

Hard hook crane: take 20%

Internal Force Calculation of Crane Beam

When calculating the internal force of the crane beam, since the crane load is a moving load, according to the method of influence line in structural mechanics, the most unfavorable position of the crane load required for each internal force needs to be determined first. And then calculate the maximum bending moment of the crane beam and its corresponding shear force.

Welding Line Between Flange and Web Plate

In addition to the horizontal shear stress, the upper flange weld line also bears the vertical stress caused by the crane wheel pressure; the lower flange weld line is only subjected to the horizontal shear stress between the flange and web.

For the heavy-duty crane beam, the connection between the upper flange and the web shall adopt the penetrated welded T-joint as shown in the picture below. The quality of the weld shall not be lower than in the second grade. At this time, it is not necessary to check the weld strength.

Connection Between Crane Beam And Column

When the crane beam is located on a frame column with column bracing, a connecting plate should be added between the lower flange and the crane platform and connected by welds or high-strength bolts.

Arrangement of Wall Beam Structure

When the column distance is greater than 12m, then the wall bracket columns need to be set between the main columns, and the wall bracket column distance is 6m. A wall beam should be set on the upper and lower edges of the wall and window frame. Set the tie rod on the wall beam to reduce the vertical deflection, and set the diagonal beam on the most upper wall beam. According to the column distance, the wall beam can be made to be simply supported beam or continuous beam.