Pushover Analysis and Seismic Response of UHPC Two-Column Bridge Bent

Advanced behavior of Ultra High Performance Concrete (UHPC) is attracting a growing interest in the construction industry worldwide. Currently, UHPC is used widely in bridge deck joints and connections, while it has a great potential to be extended to larger structural applications. However, the structural behavior of UHPC for larger components is still not fully understood. The objective of this study is to better understand the overall behavior and failure mechanism of UHPC components (mainly bridge columns) using detailed finite element modeling. In particular, this paper investigates the validity of Total Strain Crack model, as a readily implemented model in DIANA FEA software, in capturing UHPC columns failure mechanism. The uniaxial behavior of UHPC in tension and compression are independently defined using the existing uniaxial stressstrain curves from the literature. The pushover response of a two-column bent of a prototype bridge with the typical geometry available in Caltrans Bridge Academy documents is studied. Besides, a reference two-column bent, of conventional concrete with the same geometry, is modeled. The reference bent is used to investigate the relative increases in strength and ductility capacities of UHPC column compared to the conventional one. Furthermore, the effect of different reinforcement ratios, steel grades and steel hardening effects on the overall behavior of UHPC columns are investigated.