Experimental and analytical evaluation of HPFRC (high performance fiber reinforced concrete) plinths in precast girder bridges

Abstract

Thin reinforced concrete plinths are often used to make up for the difference between the flat top surface of elastomeric bearing pads and the sloped bottom side of the precast of cast-in-situ girder. In thin concrete elements, steel reinforcing bars cannot be used which leads to formation of cracks in the concrete plinth and/or damage of the concrete plinth during placement of the girder. This project examines the effectiveness of using high performance fiber reinforced concrete (HPFRC) in casting the plinths. An experimental program was developed for this purpose where HPFRC plinths of different sizes were cast and tested under vertical loads. The structural performance of the plinth was closely monitored during testing (mainly crack propagation and deformation). Note in the test that full scale elements were used (e.g. bridge girder vertical load, HPFRC plinth, elastomeric bearing pad and reinforced concrete pedestal). Analytically, the HPFRC plinth is analyzed as a beam on elastic foundation as the supporting elastomeric bearing pad is highly compressible. Finally, recommendations are made to facilitate its practical use in bridge construction. Note that the materials used and mixes are taken from previous projects where they were successfully used.