Structural steel and columns

Use this page as a guide on how to erect structural steel and raise columns.

What is structural steel?

The use of structural steel in the construction of multi-storey building construction used to be very common. That was until the development concrete reinforced design. But recently, structural steel design has made a comeback in multi-storey work.

Portal frame construction is also widely used for low-rise factories and warehouses.

Structural steel is used in the construction of:

• power stations
• smelters
• refineries
• bridges
• transmission towers
• communications towers
• other industrial projects.

How to erect structural steel

Structural steel is basically a skeleton, designed to support a building.

The first section must be fully plumbed and wind braced. This is to ensure stability for the rest of framework.

As erection continues, the wind bracing must be fitted. In some "A-frame" or "saw tooth" type buildings, which are long and narrow, the building may have to be guyed for support until each wind brace bay is erected.

Columns should be guyed to prevent the holding down bolts from pulling out. This can cause the column to collapse unless engineering allows for free standing.

Any guys or propping should be engineered.

A competent person should make sure that every column base is level. They do this by using a laser level or another device before starting to erect the columns.

There should be a packer (elevation pad) underneath every column. If the column bases are not level the steel will not be plumb. It can be very difficult to wedge up steel especially if the steel is heavy.

How to raise columns

The mass (weight) of any steel must be known for lifting into place. When ordering cranes to raise columns, a second crane may be required to "float" in the base.

To make sure that columns hang vertically, they should be slung as near to the top as possible.

Here's how to lift columns with a reeved sling:

• make sure that the sling is wrapped around twice then nipped (round turn)
• as the sling is wrapped around, incline the sling toward the nip, stopping the sling from slipping when the column becomes vertical.

The column must be packed to prevent the sling from being damaged by the sharp edges of the column. The packing has to be tied or secured to prevent it from dropping out when the slings slacken as the column is landed.