Erection Engineer
Erection Engineering – Why it is so important in the lifting of prefabricated concrete elements.
Over the past several months there have been a couple of incidents around the country involving precast concrete products that have unexpectedly dislodged from cranes during installation. While each of the incidents have been quite different, in each case, incorrect installation of the engineered lifting system was a contributing cause. Interestingly, in none of the cases has the lifting system itself, as designed, been identified as a cause of the incident. These incidents have however raised questions about how lifting systems are installed and whether an Erection Engineer was engaged as detailed in the National Code of Practice for Precast, Tilt-Up and Concrete Elements in Building Construction.
The importance of the Erection Engineer and their role in the manufacture, handling, transport and erection of prefabricated concrete elements is often overlooked. The Erection Engineer is the person who before a project even starts is involved in understanding how the prefabricated concrete elements will be handled during manufacture and erection. It is with this innate understanding that the Erection Engineer is able to calculate the likely applied loads that the anchoring system will absorb, taking into account the suction forces during manufacture, sling angle effects during lifting and also dynamic loads induced during element movement. Having calculated these loads, the Erection Engineer can select an appropriate engineered lifting system and with the published technical data from the manufacturer, design the lifting points of the elements to suit. Only once this process is complete can the Erection Engineer sign-off to say that the lifting design complies with Australian Standard AS3850-2003 and the National Code of Practice for Precast, Tilt-Up and Concrete Elements in Building Construction.
It is worth noting that the role of the Erection Engineer extends beyond just the lifting design and that the Erection Engineer commonly engages a third party to provide the certified lifting designs. As long as the third party holds appropriate engineering qualifications (like the design departments of most reputable engineered lifting suppliers like Reid and also several major precasters around the country) the requirement of the standard and the code can still be satisfied.
Once the certified lifting point design has been completed, the next key step in the process is to communicate the various rigging designs to the precaster who is going to manufacture the prefabricated concrete elements (rigging configurations for stripping and handling in the yard) and also to the project appointed crane company (rigging configuration for installation/erection) who are going to install the units. While there are various methods used to communicate this information, the most important step is for all parties to follow the rigging designs as detailed. If for whatever reason, the specified rigging details cannot be achieved, it is crucial that the Erection Engineer is contacted so that they can verify the proposed changes in light of the engineered lifting system that has already been selected.
Finally, the Erection Engineer also has a part to play in the actual manufacture of the prefabricated concrete elements. If the precaster is unable to install the specified engineered lifting system in accordance with the certified lifting point design and/or the manufacturer’s stated installation practices, the Erection Engineer must be involved. The Erection Engineer, in possible consultation with the manufacturer of the specified engineered lifting system, must determine how the element can be safely lifted in light of the issues identified.
It is the combination of these simple, but important steps that ensure prefabricated concrete elements are manufactured, transported and installed safely.