Seismic Response of RC Deck-Stiffened Arch Existing Bridges

The arch bridges are one of the oldest type of structures and have always expressed a strong aesthetic value. Reinforced Concrete (R C) arch bridges are today still one of the most important part of transportation systems. These bridges have specific peculiarities that make particularly complex the assessment of their behavior under both the static and dynamic loads and, consequently, of their safety. In this paper, attention is focused on a specific arch bridge typology: the "Maillart-Type Arch Bridges", which are characterized by a very stiff deck beam and a slender and wide vault, connected by means of slender piers, often wall-like and lightened by central windows. In analogy with other existing RC structures designed without attention to details of concrete elements (i.e. minimum stirrups amount, lower limit for reinforcement bars), these arch bridges can be damaged by loading conditions non considered in the design of the time, such as the seismic ones. The present work is aimed to analyze the seismic response of Maillart-Type RC arch bridges. An example of such an arch bridge has been simulated following the design procedures usually adopted in the 1945s, i.e. considering the only gravitational loads of the time. The case study has been analyzed with a three dimensional model generated in a Finite Element software. Then, the effects of seismic loads, evaluated according to the recent Italian guidelines, have been analyzed by means of dynamic linear analysis in order to carry out safety checks in terms of strength capacity in the main structural elements (arch, beams, columns).