Flexural Behavior of T-Shaped UHPC Beams with Varying Longitudinal Reinforcement Ratios.

Rui Zhang,Xi Li,Xiaosen Yang,Kedao Chen,Peng Hu

doi:10.3390/ma14195706

Rui Zhang, Xi Li + Show 3 more

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https://doi.org/10.3390/ma14195706

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Abstract

In order to investigate the transverse flexural behavior of the UHPC waffle deck, a total of six T-shaped UHPC beams, with varying longitudinal reinforcement ratios, were tested and analyzed. The experiments, including material tests of UHPC and beam tests, were conducted. The material tests of UHPC revealed that strain-hardening behavior in tension was exhibited, and the ratio of uniaxial compressive strength-to-cubic compressive strength was 0.85. The beam tests showed that all the T-shaped UHPC beams, even without longitudinal rebar, exhibited ductile behavior that was similar to that of properly reinforced concrete beams. As the longitudinal reinforcement ratio increased, more flexural cracks developed and a larger load-carrying capacity was provided. Furthermore, the sectional analysis for the ultimate flexural capacity of T-shaped UHPC beams was conducted. Simplified material models, under tension and compression, for UHPC were developed. Based on the reverse calculation from the experimental result, the relation between reduction factor to the ultimate tensile strength of UHPC, and longitudinal reinforcement ratios was formulated. As a result, the predictive equations for the ultimate flexural capacity of T-shaped UHPC beams were proposed, and agreed well with the experimental results in this study and existing studies, which indicates good validity of the proposed equations.

Highlights

A drawback of the existing study is the limited specimens and insufficiency in investigating the effect of the longitudinal reinforcement ratio on the flexural behavior of T-shaped Ultra-high-performance concrete (UHPC) beams, which results in unsatisfied accuracy for the existing predictive equations of the flexural capacity of T-shaped UHPC beams
This study presents an experimental and theoretical study on the flexural behavior of T-shaped UHPC beams with varying longitudinal reinforcement ratios
The tensile stress–strain relationship and compressive properties of UHPC were obtained based on uniaxial tension and compression tests

Summary

Introduction

Ultra-high-performance concrete (UHPC), as one kind of emerging fiber-reinforced cementitious composite, characterized by its excellent mechanical performance and durability, was developed in 1970s [1,2,3], and has aroused interest all over the world in recent decades. Different from conventional concrete, UHPC contains a matrix with densely packed particles and a certain volume fraction of steel fibers. Attributing to the low waterto-binder ratio and high compactness, UHPC has extremely low permeability [4], which results in excellent durability. UHPC exhibits ultra-high compressive and tensile strengths, up to 150 MPa and 5 MPa, respectively, which are much larger than those of conventional fiber-reinforced concrete (15–80 MPa in compression and 1–3 MPa in tension) [5]

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