Hybrid testing for evaluation of seismic performance of highway bridge with pier made of HyFRC

Abstract The present research is focused on Hybrid testing of a highway Reinforced Concrete (RC) bridge, wherein fibres available in India were used to improve the seismic performance of bridge pier. In order to arrive at best possible fibre proportions to be used, prisms made of conventional concrete and Hybrid Fibre Reinforced Concrete (HyFRC) were first tested to account for variability in fibre proportions. Two types of steel and polypropylene fibres available in India were used, where prisms made of HyFRC exhibited enhancement in energy dissipation capacity. HyFRC was used by previous researchers to investigate their performance in isolated structural elements, but no such research papers are found, wherein structural elements made of HyFRC were investigated using Hybrid testing. Scaled bridge piers of an existing RC bridge designed for most active seismic zones in India and made of conventional concrete as well as HyFRC were considered as experimental elements in the hybrid testing under the action of recorded earthquake excitation of different intensities. After completion of the hybrid testing, cyclic tests were carried out to find the ultimate capacity of these test specimens. Pier specimens made of HyFRC outperformed specimens made of conventional concrete in terms of all the seismic performance parameters, such as improved damage tolerance, enhanced energy-dissipation capacity, higher stiffness at any drift ratio, improved load-carrying capacity and ductility. Detailed strain measurements in concrete and reinforcing bars revealed the merits of HyFRC over conventional concrete as measured strain values were appreciably lesser at any load level.