Title:
Shear Behavior of Reinforcing Bar-Free Ultra-High-Performance Concrete Considering Axial Load Effects and Fiber Alignment
Author(s):
Abdulrahman Salah, Dimitrios Kalliontzis, John S. Lawler, and Elizabeth I. Wagner
Publication:
Structural Journal
Volume:
122
Issue:
2
Appears on pages(s):
215-230
Keywords:
axial load effects; biaxial loading; direct tension test (DTT); fiber alignment; shear behavior; ultra-high-performance concrete (UHPC); universal panel tester (UPT)
DOI:
10.14359/51743306
Date:
3/1/2025
Abstract:
Ultra-high-performance concrete (UHPC) enables thinner, longer-span elements with fewer or no reinforcing bars. This study investigates the shear behavior of reinforcing bar-free UHPC panels with a thickness of 4 in. (101.6 mm) and 2.0% volumetric content of straight steel fibers. The panels were tested under combined shear and axial loads using the universal panel tester (UPT) facility. The UPT experiments were complemented with small-scale direct tension tests (DTTs) and large-scale tension strip tests (TSTs) to investigate the effect of UHPC tensile characteristics on shear. The panels exhibited ductile responses with post-peak residual shear capacities higher than 20% of the maximum shear stress, with the TSTs providing an improved correlation to UHPC shear than the DTTs. Test results showed that the relative effect of axial loads on UHPC shear can be greater than the relative effect on conventional concrete per ACI 318. It was also found that a correlation exists between fiber alignment and UHPC’s tensile behavior, which can alter the localization stress by as much as 39%.