Challenges and perspectives for integral bridges in the UK: PLEXUS small-scale experiments

This study focuses on the investigation of the factors that have limited, so far, the development of a consistent design and assessment approach for integral bridges (IBs). This paper presents a review of previous research and current design practices for IBs, followed by an overview of monitoring studies in the laboratory and in the field. As part of the UK Collaboratorium for Research on Infrastructure and Cities–Priming Laboratory EXperiments on Infrastructure and Urban Systems experimental campaign, a small-scale 1 g physical experiment is described. The test aimed to simulate the soil–structure interaction arising from seasonal expansion and contraction of the bridge deck and assess the performance of different monitoring techniques. Pressure cells were used to measure the lateral stresses behind the abutment wall, particle image velocimetry was employed to monitor the soil behaviour behind the abutment and linear variable differential transformers were used to monitor the backfill surface movements. By combining the data from these instruments, a preliminary assessment of the soil–structure interaction behaviour of the idealised integral abutment under seasonal thermal loading has been obtained. These monitoring methods and the associated understanding of IB behaviour gained from the tests provide definitive evidence for the development of monitoring systems for larger-scale physical tests and field monitoring systems for IBs.