Securing precast concrete panels

Background

Recently, a fixed precast concrete panel collapsed onto a mobile crane after the panel’s securing clips disengaged from the steel beam when the beam flexed. This happened while an infill panel was being manoeuvred into position between the panel and another secured panel (Figure 1).

The panel crushed the crane operator’s cabin. Fortunately the operator jumped clear and only suffered minor injuries. This incident could have resulted in death or serious injury to the operator or other site workers.

The panels were cladding being installed onto a portal steel frame and were secured to the steel by metal clips bolted to inserts cast into the panels (Figure 2). The clips were to be eventually welded to the steel frame but at the time relied on a clamp connection.

Control measures

When undertaking this type of concrete panel erection, ensure:

• the work is planned, including the development of an erection plan
• lifting equipment is appropriate to the task and panel type
• the work is monitored and supervised by a competent person who is experienced in concrete panel erection
• a site specific safe work method statements (SWMS) is developed and followed
• the crane and other installation plant is positioned to minimise the risk to workers if the lift fails
• the erection plan and panel installation sequence is available onsite and followed
• panels are rigged in a manner that prevents the crane hook and rigging assembly coming into contact with the steel frame
• workers not involved with the work are prevented from accessing the works area.

Design considerations

Consider improving the type of connection used to secure concrete panels to the steel work during the erection process, especially when infill panels are being positioned. Changes to connection methods should be approved by the design or erection engineer. This may involve:

• welding some or all panel clips on adjacent panels
• using an engineered bracket system instead of clips
• fitting panel clips on both sides of the steel beam (Figure 3).

Further information

Further information on precast panel installation can be obtained from:

• WorkSafe Industry Standard – Precast and tilt-up concrete for buildings
• Australian Standard 3850 – Tilt-up concrete construction

This alert contains information following the WorkSafe Victoria’s inquiries into the incident at the date of this report. The information contained in this report does not necessarily reflect the final outcome of the WorkSafe’s action with respect to this incident. The WorkSafe does not warrant the information in this report is complete or up-to-date, and does not accept any liability to any person for the information in this report, or its use.