China Steel Structure

• Easy and quick construction.

  All main components of China lightweight steel structure are prefabricated in the factory and then erected at the site.

• Large span.

  The steel building enables large span to be constructed with small construction depth.

• Great flexibility.

  The structural steel can be bend without cracking, making it much safer to construct the industrial buildings as compared to concrete.

• Excellent fire resistance and corrosion resistance.

  The steel in buildings is usually protected from fire or corrosion by wrapping it with boards or spray-on material.

• High adaptability.

  The structure can be easily re-designed in future, such as to modify, strengthen and extend the building.

• High utilization.

  The steel can be recycled and reused without losing its quality and strength.

Primary components: steel columns, steel beams, wind-resistant columns and runway beams.

Secondary components: purlins (C-shaped, Z-shaped), purlin braces, horizontal and vertical bracing systems.

Building envelop: color steel tile, color steel sandwich panel.

All the main components of steel structures China are pre-engineered in the manufacturer’s factory, including pre-punched, pre-drilled and pre-welded, and then connected and set up at customer site. There are several different ways to connect the structural steel, including:

• Welding: automatic operation without weakening the cross section, good tightness at the joint and high structural rigidity
• Riveting: easy to check, excellent resistance to dynamic change
• Ordinary bolt connection: easy to assemble and disassemble
• High-strength bolt connection: good elasticity, large bearing capacity, compact connection

Column Foot Installation Issues:

1. Problems with embedded parts: the overall layout is offset; the elevation is wrong; the threaded fasteners are not protected. This will directly cause the bolt holes of the steel column bottom plate to be misaligned, resulting in insufficient thread length.

Solution: The China industrial steel structure construction unit cooperates with the civil construction unit to complete the embedded parts work. Before the concrete is poured, the relevant dimensions and the fixation must be reviewed.

2. The anchor bolt is not vertical: the horizontal error of the embedded anchor bolt after the foundation construction is too large. After installation, the pillars are not in a straight line, which makes the appearance of the steel building unsightly, brings errors to the installation of the steel columns, and affects the structural forces.

Solution: The anchor bolt installation should first level the bottom plate with the lower adjusting bolt, and then fill it with secondary grouting with non-shrinkage mortar. During anchor construction, fixed anchors such as steel bars or angle steels can be used.

3. Anchor bolt connection issues: the column anchor bolt is not tightened, and the backing plate is not welded to the bottom plate.

Solutions: Welded anchor rods and nuts should be adopted; on the outside of chemical anchor bolts, fireproof paint and heat insulation treatment should be taken to prevent the anchoring performance from being affected in the event of fire.

Connection Issues:

1. High-strength bolt connection issues

The bolt surface does not meet the requirements, causing the bolts to be difficult to install, or the degree of bolt tightening does not meet the design requirements. This may be caused by impurities such as floating rust and oil stains on the surface of the bolts, and burrs and weld bumps on the bolt holes.

Solution: Floating rust, oil stains and bolt hole defects on the surface of high-strength bolts should be cleaned up one by one. Before use, it must be treated with rust prevention. The bolts used for trial assembly must not be used during formal assembly. The bolts should be kept and distributed by special personnel.

2. The bolt thread is damaged, and the screw cannot be screwed into the nut freely, which affects the assembly of the bolt. This may be due to severe corrosion of the thread.

Solutions:

• Bolts should be carefully selected, and pre-assembled after cleaning and derusting.
• Thread damaged bolts cannot be used as temporary bolts, and it is strictly forbidden to force them into the screw holes.
• The pre-selected bolt components should be stored in sets and cannot be interchanged during use.

On-site Welding Issue:

It is difficult to guarantee the quality of on-site welds; the first and second level welds with design requirements for full penetration are not used for ultrasonic flaw detection; the main beams and columns on the floor are not welded; and the pilot arc plate is not used for welding.

Solutions:

• Before welding the China steel frame structure, check the qualification certificate of the welding rod, select the welding rod according to the design requirements, and use it according to the instructions and operating procedures.
• There should be no cracks or weld bead on the surface of the weld.
• The first and second level welds must not have pores, slag inclusions, arc pit cracks, and the first level welds must not have defects such as undercuts and underfills.
• The first and second level welds shall be subjected to non-destructive testing as required, and the welder’s steel seal shall be inspected at the specified welds and positions.

Deformation of Components:

1. The components are deformed during transportation, and there are dead or slow bends, causing the components unable to be installed.

• The deformation caused by welding during the production of the component generally produces a slow bend.
• When the components are to be transported, the supporting points are unreasonable, causing dead bends or slow deformation of the components.
• Deformation caused by collision during component transportation usually generates dead bends.

Precaution:

• When components are made, reduce welding deformation.
• The assembly sequence should obey the welding sequence, use assembly molds, and set enough brackets to prevent deformation.
• Pay attention to the reasonable allocation of pads during transportation.

Solutions:

• The dead bending and deformation of components are generally treated by mechanical correction method. That is to use jacks or other tools to correct or correct after oxyacetylene flame roasting.
• When the structure undergoes slow bending deformation, oxyacetylene flame heating is used for correction.

2. The component is arched, and the value is larger or smaller than the design value. If the arching value of the component is small, the beam will bend down after installation; when the arching value is large, the extruded surface elevation is likely to exceed the standard.

Reasons:

• The size of the component does not meet the design requirements.
• During the erection process, no correction was made based on the discrepancy between the actual measured value and the calculated value.
• For bridges with small spans, the degree of camber is small, so they are ignored during assembly.

Solutions:

• Inspect strictly according to the allowable deviation of the steel structure.
• After the rods are installed and the construction of the joints is completed, the camber must be measured and adjusted during the construction.
• In the small-span assembly process, the accumulated deviation should be strictly controlled, and measures should be taken to eliminate the influence of welding shrinkage.