Innovative connector for offsite construction promises productivity boost

Advanced self-locking technology targeting onsite installation of offsite constructed buildings.

A Canadian researcher has developed a self-locking connector targeting larger offsite-constructed buildings that require an efficient solution to enhance and accelerate onsite installation. (Photo credit: Circerb)

Laurence Picard undertook a Ph.D. in mechanical engineering at Laval University, Quebec City. Her project, supervised by Pierre Blanchet and André Bégin-Drolet, aimed to develop a self-locking connector to quickly and securely join prefabricated modules onsite, optimising the benefits of prefabrication for multi-storey light-frame modular construction.

The dilemma they sought to address is that erecting prefabricated modules involves manual operations which can be time-consuming and require certain areas of the modules to remain accessible and unfinished. Picard’s research sought to streamline this process by developing a device to expedite the fastening of prefabricated elements.

An extensive list of functional and technical design specifications guided the project. The connector needed an automated locking mechanism, vertical movement, easy factory manufacturing, visual or sound confirmation of the connection, and quick unlocking capability within three minutes. It also had to be integrated within walls and floors without affecting the building’s vertical load paths, and it needed significant tensile, compressive, and shear capacities. Computer-aided designs and digital simulations facilitated the design process, followed by 3D printing and experimental testing of prototypes to finalise the design.

The result of their efforts is a self-locking connector comprising two main components: the floor connector and the ceiling connector. The floor connector, attached to the main floor beams, houses the automatic locking box, while the ceiling connector, attached to the ceiling beam, includes a shaft that rises upwards. During assembly, the upper module descends onto the lower module, guiding the shaft into the floor connector’s cavity. The latch mechanism deploys upon contact, completing the connection.

Large-scale test carried out with the connector on a two-storey house (photo credit: Circerb)
Large-scale test carried out with the connector on a two-storey house. (photo credit: Circerb)

Laboratory tests evaluated the connector’s tensile, compressive, and shear capacities, also showed promising results. Subsequent field tests on a two-storey house comprising four modules and a concrete basement confirmed its performance.

The connectors also served as attachment points for modular handling and lifting, presenting both benefits and challenges. Although the lifting function was efficient, it also imposed considerable design constraints and did not offer significant time savings compared to traditional methods.

A patent has been secured for the connector, and it has been licensed for commercial use.


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