Concrete failure of composite dowels under cyclic loading during full-scale tests of beams for the “Wierna Rzeka” bridge

Abstract

Composite dowels with clothoidal shapes constitute a new kind of shear connection that is used in modern composite bridges constructed in the European Union. These dowels are well established, and they are important steps in the development of composite constructions. This new chapter in the development of composite dowels started with the construction of the first railway bridge using composite dowels, which was the “Wierna Rzeka” bridge in Poland, wherein clothoidal-shaped composite dowels were applied for the first time. This structure has been subjected to significant fatigue loads, and the behaviour of this new form of fatigue-resistant composite dowels must be seriously investigated under cyclic conditions. A full-scale beam test under cyclic loading was conducted to investigate the behaviour of the girders and shear connection. Failure of concrete dowels under cyclic loading was the main focus of the test and was finally achieved herein. This paper presents the behaviour and failure mechanism of a composite dowel shear connection due to concrete failure under cyclic loading, which has not been previously reported in the literature. The test presented herein is a beam test with a large steel web thickness (27 mm), which is the first beam test where concrete dowel failure was achieved. However, this is a test of a so-called general composite section, and the complicated behaviour of such a structure differs from that of a standard composite section.