Researchers look at adhesive use in composite beam connection

A team of researchers in China, led by Junhu Shao, has performed a series of tests to see if adhesives used to connect steel-concrete beams (SCCBs) improve performance compared to mechanical connectors.

Steel-concrete composite beams are widely used in the construction of concrete flooring, bridges and decking. Steel beams are usually attached to concrete slabs by shear connectors.

The research team in China studied how concrete structures that use SCCBs can develop faults including cracks, detachment of bonding surfaces and concrete slab crushing. They wanted to know if bonding using adhesives was more effective at preventing these faults compared to mechanical connectors.

Bending tests used displacement and strain testing devices to evaluate the structural performance of adhesive and mechanical connectors. This provided a comprehensive understanding of the SCCBs’ behaviour under bending loads.

The team found that the ideal thickness of adhesive was between 4 mm and 6 mm to ensure good adhesion and effective load transfer between the concrete and steel components. SCCBs bonded with a 6 mm thickness of epoxy resin were found to be able to support 16.8% heavier loads than systems using mechanical connectors.

The study concluded that SCCBs bonded with adhesives have higher load bearing capacity and rigidity compared to mechanical connectors. The tests indicate that adhesives lessen the risk of the concrete slabs cracking. The researchers say that further studies are required into the best way to connect steel-concrete beams. Details of the study are published in Nature, the world’s leading multidisciplinary science journal.