Key points of safety and quality of space frame

 

一. Common quality problems of space frame

(1) Bending deformation or partial fracture of the rod;

(2) The connection of rod sealing plate or cone welding seam is broken;

(3) Deformation or fracture of nodes;

(4) The welding seam is not full or has bubbles, slag inclusions and micro cracks exceeding the specified standards;

(5) The high-strength bolt is broken or pulled out from the ball joint;

(6) The rod parts touch at the node, and when the upper string support, the support abdominal rod collides with the support structure;

(7) Displacement of support node;

(8) The deflection is too large, exceeding 1.15 times of the corresponding design value specified in the design.

二. The main reason

1. Design reasons

(1) Unreasonable selection of structural form, unreasonable matching of member cross-sections, ignoring the effects of initial bending, initial eccentricity and secondary response of members, under-calculation and omission of loads during design, or improper load combination;

(2) Unreasonable selection of materials;

(3) Errors in the selection of calculation methods, assumptions, and computer procedures have not been found;

(4) After structural design calculation, material substitution is carried out without review, resulting in the appearance of strength members beyond the design value;

(5) Wrong or incomplete drawings. If the dimensions are in disorder, the design description is unclear, the material, process requirements,

2.Reasons for processing

(1) Management is chaotic, and different specifications, steel grades, materials and materials are mixed;

(2) The blanking size of the component is wrong, and the slenderness ratio of the component does not meet the design requirements;

(3) The cut-out of the grid member is not opened, the welding seam is not lined or welded according to the design requirements

(4) The connecting high-strength bolts are unqualified;

(5) The component processing is defective, and the angle deviation of the bolt ball hole is large;

(6) The weld quality is poor, and the weld fillet size does not meet the design requirements;

3.Reasons for installation

(1) When the ground is assembled, the support points are uneven, the force is unreasonable, errors accumulate during assembly, and individual members are wrong, which causes the force to change, causing deform.

(2) The welding process and welding sequence are wrong, which will cause welding stress and lead to deformation.

(3) During the overall hoisting, the selection of the lifting point is unreasonable, and the lifting point has not been checked for reaction force, member overstress check, deflection check, and necessary reinforcement measures for the excessive stress.

(4) During the overall hoisting, the lifting speed of each hoisting point is different, and the displacement and height difference exceed the allowable range, resulting in deformation and damage.

(5) The selection of the construction plan was wrong, the plan was not selected reasonably according to the space structure form and the on-site construction conditions, and the geometrically invariant system could not be formed during installation, resulting in deformation and damage.

(6) The embedded parts, embedded bolts or column tops of the space frame support have a large deviation, which is difficult to be placed in place and forced to be in place, resulting in changes in the bearing conditions of the support and deformation of the rods.

(7) The installer is careless, and the rod position and ball angle are wrong.

(8) When the string is supported, the error accumulation is too large, which causes the support to be displaced, and the web rod and the supporting surface collide.

LF is a professional manufacturer and engineering company for space frame and steel structure projects.Do you have a construction project we can help with? We are always ready to help you!Website:www.lfspaceframe.com