Half-joint assessment of concrete bridges: strut and tie model development and FEM validation

Monitoring and assessment of structures is one of the most interesting and urgent topics that occupies a central role in research. Bridges are no exception: due to their location and structure they are often subjected to critical environmental conditions and load cases. A widely exploited structural scheme is the dapped end beam, obtained using a particular joint (half-joint) which geometry does not allow direct inspections in its critical zones. The aim of the thesis is to provide a useful generic tool: a safe, fast, reliable indication of the strength of the element, a model that can be of a vast application, with different reinforcement layouts, different geometries. A lower bound of strength based on the strut and tie method is identified in order to have an indication of the ultimate resistance of the joint: existing strut and tie models are studied and implemented, until a new model is defined and applied to several existing half-joints in order to test its adaptability. The analytical model is then validated by means of the finite element program ATENA 2D, with non-linear analysis of selected cases among the analytical model applications. The numerical analysis confirms all results coming from the analytical model application, also providing an excellent agreement with a laboratory test output. This thesis result can be of spread use and basis for further interesting research topics, since it can represent the first step towards a new strategy for half-joint monitoring.