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Increased load capacity for Europe's bridges

Published: 28 January 2021

Research at Luleå University of Technology is now gaining more and more practical applications including increased load capacity for two bridges in southern Norway, Fidge and Sagstu. Europe's old steel bridges need increased load capacity, and one way to do this is to create composite action in the old bridges where the concrete deck is not attached to the steel beams.

"With great commitment and professional skill, Luleå University of Technology has contributed to carrying out its own research work in the strengthening projects. Equally important is the work that has been done afterwards with test load to verify that the strengthening method really gives the expected capacity increase", says Knut Grefstad at the Norwegian Public Roads Administration.

Thanks to a scientific article from Luleå University of Technology published for the IABSE conference (International Association for Bridge and Structural Engineering) 2016, the Icelandic bridge designer Magnus Arasson wanted to to create composite action for two existing Norwegian single-span bridges that were built without shear connection between the steel beams and the concrete deck.

Installation of coiled spring pin
Installation of coiled spring pin

"At Ramboll's initiative, The Swedish Transport Administration strengthened the large Pitsund bridge by introducing composite action, with so-called coiled spring pins with a diameter of 20 mm. Holes are drilled through the upper flange of the steel beams into the concrete, after which Coiled Spring Pins are inserted to ensure that the concrete deck cannot slide on the steel beams. In this way, the concrete and pavement do not need to be replaced, and the traffic can continue during the reinforcement work", says Peter Collin, professor in Structural Engineering at Luleå University of Technology.

In Robert Hällmark's doctoral dissertation, the Pitsund Bridge was studied by measuring both stresses and deformations between steel and concrete, with satisfactory results. Robert Hällmark is currently an adjunct professor  Luleå University of Technology.

The research group in Structural Engineering at Luleå University of Technology have also measured one bridge, Sagstu, loaded before and after strengthening, and plan to show the results at a bridge conference in Ghent in September 2021, organized by IABSE.

Peter Collin

Peter Collin, Professor

Organisation: Structural Engineering, Structural and Fire Engineering, Department of Civil, Environmental and Natural Resources Engineering
Robert Hällmark

Robert Hällmark, Adjunct Professor, 1:stReaserch ingeneer

Organisation: Structural Engineering, Structural and Fire Engineering, Department of Civil, Environmental and Natural Resources Engineering