Flexural Behavior and Design of Ultrahigh-Performance Concrete Beams

Rafic G El-Helou,Benjamin A Graybeal

doi:10.1061/(asce)st.1943-541x.0003246

Abstract

Flexural Behavior and Design of Ultrahigh-Performance Concrete Beams

Highlights

Flexural design of concrete members in the United States is founded on mechanical models and sectional design methods specified in the AASHTO Load and Resistance Factor (LRFD) Bridge Design Specifications, referred to as AASHTO LRFD BDS (AASHTO 2020), and the American Concrete Institute (ACI) 318-19 Building Code Requirements for Structural Concrete, referred to as ACI 318-19 (ACI 2019)
The stresses on strained cross sections can be obtained from appropriate uniaxial stress-strain models for Ultrahigh-performance concrete (UHPC), which are different from those traditionally used for conventional concrete
The maximum moment capacity of UHPC beams can occur at crack localization when the strain in the extreme tensile layer is equal to the UHPC localization strain, or at compression crushing prior to localization when the strain in the extreme compression layer is equal to the UHPC ultimate compression strain

Summary

Introduction

Ultrahigh-performance concrete (UHPC) is an emerging class of cementitious composites, commonly proportioned using particle packing theory and reinforced with discontinuous steel fibers, that offers superior mechanical and durability characteristics compared to conventional and other fiber-reinforced concretes (De Larrard and Sedran 2002; Graybeal 2006a; Habel et al 2006; Lepech and Li 2009; Bencardino et al 2010; Magureanu et al 2012; Wille and Naaman 2013; El-Helou 2016). The loss of the UHPC fiber-bridging resistance mechanism leads to a decrease in the flexural resistance of the member at the localized section, and in many cases, the load and deformation sustained by the member prior to localization will generate a significant increase in curvature at the localized section, leading to the local straining of the tensile reinforcement and the hinging of the beam around the localized crack These observations accentuate the need for a novel design and analysis framework that accounts for the enhanced mechanical properties of UHPC and captures the new flexural failure modes expected with this class of materials. 0.91 m (3 ft) east reaction spherical bearing east load cell transfer plate west end top LVDTs: T1 T2 T3 T4 T5 east end bearing plate roller support reaction

B3 B4 B5

12 Batch A 10

B-1 B-2 B-3 B-4

Summary and Conclusions

Findings

Data Availability Statement