Experimental evaluation of the corrosion influence on the structural response of Gerber half-joints

The assessment of the Gerber half-joints (or saddles), widespread in the infrastructure heritage of different countries, is nowadays a topical problem since they are often affected by chloride corrosion phenomena due to their positioning under the deck joint. In this paper, the influence of steel rebar corrosion on the experimental response of Gerber half-joints is experimentally analysed and discussed. In particular, four elements were cast in Laboratory of University of Rome “Tor Vergata” two of which subjected to accelerated corrosion, and then tested up to failure. The specimens were designed with typical strut and tie models, with the aim of achieving different failure modes governed by the concrete crush or by the tensile rebar breaking. Particular care was devoted to the corrosion process, in order to simulate decay scenarios typical of these structures. The experimental outcomes, expressed in terms of load–displacement curves, crack patterns and failure mechanisms show that also medium-slight degree of pitting corrosion can cause great reductions in capacity and ductility of the saddles, modifying, in addition, their failure mechanism. Finally, from the experimental outcomes, the sensitivity of these peculiar structures, not only to the corrosion amount, but also to its spatial distribution among the different steel rebars, and its morphology (pitting or uniform corrosion) is clearly underlined. As a consequence, the necessity to accurately and properly account for the corrosion phenomenon in the structural assessment is remarked.