Analysis of Common Quality Accidents in Steel Structure Space Frame and Portal Rigid Frame Project（Part I）

Although steel structure engineering has been widely used in recent years, many complicated problems and technical difficulties in steel structure engineering design, processing and installation have not been deeply recognized. A little carelessness, ill-consideration or inexperience in the process of steel structure design, processing and installation may lead to quality and safety accidents.

1.Common quality accidents in steel structure project-space frame, portal rigid frame

 Common quality accidents in steel structure projects

(1) Bending deformation or partial fracture of rods.

(2) Damage of rod sealing plate or cone head weld connection.

(3) Node deformation or fracture

(4) Welding seam is not full or there are bubbles, slag, micro-cracks exceeding the prescribed standards.

(5) High-strength bolts broken or pulled out of the ball nodes.

(6) Rods in the node collision, chord support when the bearing web and supporting structure collision.

(7) Displacement of bearing nodes.

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

Portal rigid frame project common quality accidents

(1) The main components are deformed and twisted.

(2) Pre-embedded parts do not conform to the drawings, specification requirements, height difference exceeds the standard, spacing exceeds the standard.

(3) The overall verticality of the steel frame and the overall plane bending over the poor, beams and columns at the end of the plate holes do not correspond to the size of the misalignment.

(4) The main stress node weld is not full or there are bubbles, slag, micro-cracks exceeding the prescribed standards.

(5) Accessory stabilizing structures such as: support, bollard, corner brace, etc. unreasonable location, or processing errors.

(6) Secondary components do not meet the quality requirements.

2.The main causes of quality accidents

Design reasons

(1) Unreasonable choice of structural form, unreasonable matching of rod section, neglecting the influence of initial bending, initial eccentricity and secondary stress of members, undercalculation and omission of loading or improper combination of loading during design.

(2) Unreasonable material selection.

(3) Failure to detect errors in the selection of calculation methods, assumptions and computer programs.

(4) After structural design calculations, material substitution without review, resulting in the emergence of over-designed strength members.

(5) Wrong or incomplete drawings. Such as size labeling confusion, unclear design description, materials, process requirements, construction procedures and special requirements of the parts have omitted.

(6) The node construction is wrong and the detail consideration is not comprehensive.

Reasons for steel structure space frame processing

(1) Chaotic management, mixed use of materials with different specifications, steel numbers and materials.

(2) Errors in the size of the components, the length and slenderness ratio of the components do not meet the design requirements.

(3) The space frame pole is not playing, butt welding seam without liner pipe or not according to the design requirements of welding.

(4) Connection of high-strength bolts failed.

(5) Defective processing of components, bolt ball hole angle deviation.

(6) Poor quality of welds, welding angle size does not meet the design requirements.