Prefabricated Columns for Steel Structure Houses

The prefabricated columns for steel structure houses are load-bearing components made of steel materials, which are prefabricated in factories and then transported to construction sites for assembly. Common types include solid H-shaped columns and hollow lattice columns, featuring advantages such as light weight and fast construction, but requiring strict control over fire prevention, corrosion resistance, and installation accuracy.

Common Types and Structural Characteristics

Prefabricated steel columns mainly fall into two categories: Solid H-shaped columns are processed and formed from solid steel, offering stable structures and suitable for scenarios with heavy loads; Hollow lattice columns are assembled into frame structures using steel bars, being lighter in weight and capable of saving steel consumption. Both types of columns possess the advantages of light weight and high strength—steel columns of the same thickness are 30% lighter than concrete columns but have stronger load-bearing capacities; they also offer high construction efficiency, as they are prefabricated in factories and assembled on-site, shortening the construction period by 50% compared to cast-in-place concrete columns.

Performance Requirements and Protective Measures

1. Fire Resistance: The strength of steel decreases sharply under high temperatures (yield strength starts to decrease at 300℃ and is almost completely lost at 600℃), so fire-resistant coatings are required. Non-intumescent (thick-coating) fire-resistant coatings are commonly used for load-bearing columns, with a thickness of 10-25 millimeters and a fire resistance limit of 2.5-3 hours. For example, an H200 steel column designed for 2.5 hours of fire resistance requires a 16-millimeter-thick coating, applied in 3-4 layers with each layer dried before applying the next.
2. Corrosion Resistance: Special corrosion protection is required for steel columns in humid environments or coastal buildings. Typically, after rust removal from the base layer, a corrosion-resistant primer is applied, followed by a fire-resistant coating, and optionally a topcoat. The sequence of operations cannot be reversed, as applying the fire-resistant layer before the primer will result in insufficient adhesion of the primer, affecting the corrosion protection effect.

Installation and Quality Inspection Points

1. Installation Accuracy: The verticality deviation of steel columns must not exceed one thousandth (e.g., a maximum deviation of 3 millimeters for a 3-meter-high column), and a theodolite is required for calibration to avoid uneven structural loading.
2. Coating Inspection: Use a thickness gauge to verify the thickness of the fire-resistant coating, avoiding voids or insufficient thickness. For example, in a project, the measurement point on the reverse side of the steel column's flange plate was only 7 millimeters, failing to meet the design requirements and requiring rework and reapplication.
3. Construction Process: Coating application should follow the thickness correspondence table provided by the coating manufacturer, ensuring that each layer is dried before applying the next to avoid cracking or peeling of the coating due to insufficient drying.