Experimental Study On The Seismic Performance Of Typical Existing Reinforced Concrete Bridge Piers With Hollow Rectangular Sections

In economically advanced countries, particularly in Europe and Italy, most of existing bridges have been constructed prior to 1980, before the advancement in earthquake engineering principles and the introduction of adequate seismic codes. These aspects , in combination with the strategic role of bridges in post- earthquake emergency management, specifically for the highway bridges, lead to the need to improve the assessme nt of the seismic capacity of existing bridge structures. Generally, important bridges have reinforced concrete hollow section piers, economically attractive. R ecent main earthquakes around the world have highlighted the inadequate seismic performance of existing hollow piers, mainly due to poor structural detailing and small web thickness . Few experimental contributions are present in literature about bridge piers designed according to obsolete codes. This study concerns an experimental campaign on poorly designed bridge piers with typical transverse section geometry (hollow rectangular ) and different aspect ratios. The specimens have been designed in order to be representative of the Italian bridge structures realized in the above- mentioned period, in part icular about materials (poor concrete and high strength steel) and reinforcement (low longitudinal and transversal reinforcement ratio). Piers have been designed and realized in 1:4 scale. Quasi -static cyclic tests under displacement control have been performed with a constant axial load. Different failure modes ha ve been observed: flexure and flexure -sh ear in particular , basically depending on the specimens’ slenderness. Design criteria, adopted setup and experimental results are described and discussed.