Analysis of common problems in steel structure design

What is the difference between a soft hook crane and a hard hook?

A: Soft hook crane: refers to the lifting of heavy objects through steel ropes and hooks. Hard hook crane: refers to the lifting of heavy objects such as clamps and magazines through rigid bodies. Hard hook cranes work frequently. The running speed is high, and the rigid cantilever structure attached to the trolley makes the hoisting weight unable to swing freely.

What is a rigid tie rod, what is a flexible tie rod?

Answer: The rigid tie rod can be pressed and pulled. Generally, double angle steel and round tube are used, and the flexible tie rod can only be pulled. Generally, single angle steel or round tube is used.

What is the relationship between slenderness ratio and deflection?

Answer: 1. Deflection is the amount of deformation of the component after loading, that is, its displacement value.

2. "The slenderness ratio is used to indicate the stiffness of the axially loaded member." The slenderness ratio should be the material property. The properties of any component, the stiffness of the axially stressed component, can be measured by the slenderness ratio.

3. Deflection and slenderness ratio are completely different concepts. The slenderness ratio is the ratio of the calculated length of the rod to the radius of gyration of the section. Deflection is the displacement value of a point after the component is stressed.

What should be considered when designing a steel structure axial tension member?

Answer: 1. Under the static load without fatigue, the residual stress has no effect on the bearing capacity of the tie rod.

2. If there is a sudden change in the cross section of the tie rod, the distribution of the stress at the change is no longer uniform.

3. The design tie rod should take the yield as the limit state of the bearing capacity.

4. The ultimate limit of bearing capacity should be considered from two aspects: the gross section and the net section.

5. Consider the efficiency of the net section.