DOI: 10.17603/ds2-qek1-qv14
title: Database for Shear Tests on Rebar-Free UHPC Considering Axial Load and Fiber Alignment Effects
title: in Shear Behavior of UHPC Considering Axial Load and Fiber Alignment

description: Ultra-high-performance concrete (UHPC) enables the design of thinner, longer-span structural elements with reduced or no reinforcing bars. This study investigated the shear behavior of 4-inch-thick UHPC panels containing 2.0% by volume straight steel fibers, tested under combined shear and axial loads using the Universal Panel Tester (UPT) facility. Complementary small-scale direct tension tests (DTTs) and large-scale tension strip tests (TSTs) were conducted to assess the influence of UHPC's tensile characteristics on shear performance. The panels demonstrated ductile responses, maintaining post-peak residual shear capacities exceeding 20% of the maximum shear stress, with TSTs providing a better correlation to UHPC shear behavior than DTTs. Notably, the impact of axial loads on UHPC shear strength was found to be more significant than that observed in conventional concrete as per ACI 318 standards. Additionally, a correlation between fiber alignment and UHPC's tensile behavior was identified, with fiber alignment effects altering the localization stress by up to 39%. This dataset accompanies the journal paper "Shear Behavior of Rebar-Free UHPC Considering Axial Load Effects and Fiber Alignment," published in 2025 (DOI: 10.14359/51743306). The publication provides a detailed overview of the shear laboratory experiments for UHPC and a discussion of the experimental results.
description: The superior mechanical properties of ultra-high-performance concrete (UHPC) allow for the design of thinner, longer-span structural elements with or without traditional reinforcing bars. This research study investigated the shear behavior of UHPC, considering the effects of axial stress fields and fiber alignment. The study encompassed laboratory tests of UHPC panels under various loading conditions using the Universal Panel Tester (UPT) facility at the University of Houston. Specifically, a set of 4-inch-thick panels with a 2.0% volumetric content of straight steel fibers was subjected to combined shear and axial loads, including both tension and compression load scenarios. Complementary to the UHPC panel tests, small-scale direct tension tests (DTTs) and large-scale tension strip tests (TSTs) were conducted to evaluate UHPC's tensile constitutive behavior and correlate findings to shear behavior. Fiber alignment analyses were performed on samples extracted from the panels and companion DTT and TST specimens to understand the influence of fiber orientation on tensile performance. Key findings indicated that axial loads significantly impact UHPC's shear strength: for example, an axial tensile load ratio of 33% can reduce the shear strength by 12.3%, whereas an axial compressive load ratio of 5% can enhance it by 77.6%. 
Additionally, fiber alignment, influenced by boundary effects induced by reinforcing bars, was found to alter the localization stress significantly. These insights suggest that UHPC's response to axial loads differs from conventional concrete, highlighting the need for tailored design considerations. The outcomes of this research provide a unique dataset aiming to optimize UHPC’s structural applications by underlining the need to understand and account for axial load and fiber alignment effects in UHPC analysis and design. The findings contribute to the development of efficient and resilient UHPC structures, benefiting the broader construction industry by informing design guidelines and promoting the adoption of UHPC in innovative structural solutions.