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Steel structure workshop - crane beam design features

by:Lida Group     2022-01-28

Steel structure workshop - crane beam design characteristics Steel beams (1), combined I-beams (2), box beams (3), crane trusses (4), etc.

The load on the crane beam Permanent load (vertical) Dynamic load, its direction is horizontal and horizontal, which is characterized by repeated action, which is easy to cause fatigue damage. Therefore, the requirements for steel are higher, in addition to the conventional requirements such as tensile strength, elongation, yield point, etc., it is necessary to ensure that the impact toughness is qualified. The components of the crane beam structure system 1. The crane beam 2. The load of the brake beam or the brake truss

The load of the crane beam The crane beam directly bears loads in three directions: vertical load (system self-weight and heavy objects), horizontal horizontal load load (braking force and rail force) and longitudinal horizontal load (braking force). The crane beam design does not consider the longitudinal horizontal load, and is designed according to the two-way bending.

Vertical load, lateral horizontal load, longitudinal horizontal load. The vertical load includes the crane and its heavy objects, and the self-weight of the crane beam. When the crane passes the track joint, the impact occurs, which has a dynamic effect on the beam. When designing, take the method of increasing wheel pressure into consideration. The lateral horizontal load is generated by the clamping rail force (the track is not smooth), resulting in a lateral horizontal force. Crane load calculation

The load specification stipulates that the standard value of the horizontal horizontal load of the crane should be the sum of the gravity g of the transverse trolley and the gravity Q of the rated lifting capacity multiplied by the following percentages: Soft hook crane: when Q≤100kN, Take 20% when Qu003d150~500kN, take 10% when Q≥750kN, take 8% Hard hook crane: take 20% GB50017 regulations, heavy duty system (work level is A6~A8) crane beam, due to crane swing The standard value of the horizontal force acting on each wheel pressure is:

The internal force of the crane girder When calculating the internal force of the crane girder, since the crane load is a moving load, first of all, it should be determined according to the method of influence line in structural mechanics. The most unfavorable position of the crane load required by the internal force, and then obtain the maximum bending moment of the crane beam and its corresponding shear force, the maximum shear force at the support, and the maximum bending moment generated in the horizontal direction under the action of the lateral horizontal load. . When calculating the strength, stability and deformation of the crane beam, two cranes are considered; for the calculation of fatigue and deformation, the standard value of the crane load is used, and the dynamic coefficient is not considered. 1. In the calculation under the action of moving load, firstly determine the most unfavorable position of the load according to the influence line method; 2. Second, find out the maximum bending moment of the crane beam and the corresponding shear force, and the maximum shear force at the support, under the action of lateral horizontal load 3. When calculating strength and stability, generally consider the most unfavorable load of two cranes; when calculating fatigue, consider one largest crane. Section Checking of Crane Beams After the most unfavorable internal force of the crane beams has been obtained, select the sections of the crane beams according to the method of section selection of composite beams in Chapter 5. When checking the sections, it is assumed that the vertical load is borne by the crane beams and the horizontal horizontal The load is carried by the reinforced upper flange of the crane girder, the brake beam or the brake truss, ignoring the eccentric effect caused by the lateral horizontal load. Overall stability check The crane beam connected with the braking structure has a large lateral bending stiffness, and the overall stability is guaranteed without checking. The overall stability formula of the crane girder reinforced with the upper flange:

Stiffness check When checking the rigidity of the crane girder, it should be calculated according to the standard load value of the crane with the greatest effect, and the dynamic coefficient should not be used. Approximate calculation formula for vertical deflection of crane girder

The upper flange weld not only bears the horizontal shear stress, but also bears the vertical stress caused by the wheel pressure of the crane; the lower flange weld only bears the vertical stress. Subject to horizontal shear stress between flange and web. For heavy duty crane girder, the connection between the upper flange and the web shall adopt the T-shaped connection weld with penetration as shown in Figure 7.91, and the quality of the weld shall not be lower than Grade 2. In this case, it is not necessary to check the weld strength.

The arrangement of the wall beam structure When the spacing between the workshop columns is greater than 12m, the wall frame columns shall be arranged between the columns, and the spacing between the wall frame columns shall be 6m; on the upper and lower edges of the wall and the upper and A wall beam is arranged at the lower edge; a brace is arranged on the wall beam to reduce the vertical deflection of the wall beam, and an oblique brace is arranged at the uppermost wall beam, and the wall beam can be made into a simply supported beam or a continuous beam according to the column distance.

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