Steel Structure Building Connection Method-Weld Connection

In the 21st century, steel structure construction is booming. Steel structure is widely used in various fields due to its advantages of high strength, high rigidity, short construction period and strong earthquake resistance.
The steel structure building is composed of many aspects, among which the steel structure connection is an important part. There are three most common connection methods, weld connection, bolt connection, and rivet connection.

Features of weld connection

  • Advantage
  • Disadvantages
* No need to perforate, no weakening of the section, saving labor and time;

* Components of any shape can be directly connected, and the connection structure is convenient;

*Good air-tightness and water-tightness, greater structural rigidity, and better integrity;

*Automatic operation can be realized.
* Welding is affected by heat, and the material is easy to become brittle;

*The residual stress of welding makes the structure prone to brittle failure, the shape and size of the structure change, and the bearing capacity of the compression member is reduced;

* Welding cracks are easy to expand;

*High requirements for materials.
Steel structure building welding
Steel structure building welding

Common Welding Defects

Collapse, undercut, burn through, slag inclusion, pits, incomplete welding, incomplete welding, pores, cracks.

Welding Quality Inspection

  • Weld quality Inspection Methods

    x-ray inspection, ultrasonic inspection, visual inspection.

  • Weld quality classification

    *The first-class welds need to pass visual inspection, ultrasonic flaw detection, and X-ray inspection;

    *Second-level welds require visual inspection and ultrasonic flaw detection;

    *The third-level weld requires visual inspection to be qualified.

Steel structure building welding inspection
Steel structure building welding inspection

Weld Level Requirements

Welding seams should be selected according to the importance of the structure, load characteristics, welding seam form, working environment and stress state, etc., and different quality levels should be selected:

  • Fatigue calculation of components, butt weld penetration

    1) For transverse butt welds with force perpendicular to the length of the weld, it should be level one when under tension and level two when under compression;

    2) Longitudinal butt welds where the force is parallel to the length of the weld shall be Class II.

  • If the component does not need to calculate fatigue

    It is required that the strong butt weld with the base metal should be penetrated, and its quality level should not be lower than Class 2 when under tension, and should be Class 2 when under compression.

  • Heavy duty system and lifting capacity

    The welds of the T-shaped joints between the web and upper flange of the heavy duty working system and the intermediate working system crane beam with the lifting weight Q≥50t and between the upper chord of the crane truss and the gusset plate are required to be penetrated. The form is generally a combination of butt joint and corner joint, and its quality level shall not be lower than Class II.

  • T joints and fillet welds

    Fillet welds used in T-joints that do not require penetration, or combined butt and fillet welds with partial penetration, and fillet welds used in lap joints, have the following quality levels:
    1) Structures bearing dynamic loads and calculating fatigue and crane beams with a lifting weight of more than 50 tons, welding seam level II

    2) For other structures, the appearance quality of welds reaches Class III.

Steel structure welding
Steel structure welding

Weld Connection Type And Weld Type

1. Weld connection type
According to the relative position of the two weldments, they are divided into flat joints, lap joints, T (top) joints and corner joints.
2. Weld type
1) Butt welds are divided into force and weld direction
A: Straight seam: the direction of the force is orthogonal to the direction of the weld
B: Oblique seam: the direction of the force and the direction of the weld are obliquely intersected
2) Fillet welds are divided into force and weld direction
A: End seam: the direction of force is perpendicular to the length of the weld
B: Side seam: the direction of force is parallel to the length of the weld
3) According to weld continuity:
A: Continuous weld: better stress
B: Intermittent welds: stress concentration easily occurs
4) According to construction location:
Overhead welding, vertical welding, horizontal welding, and overhead welding, among them, overhead welding has the best construction position, so the weld quality is also the best, and overhead welding is the worst.

Thank you for watching and look forward to cooperating with you. ibeehive steel structure company will satisfy you with high-quality products and considerate service.

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