Tension-stiffening effect in steel-reinforced UHPC composites: Constitutive model and effects of steel fibers, loading patterns, and rebar sizes

Hung, Chung-Chan; Lee, He Sheng; Chan, Si Nga

doi:10.1016/j.compositesb.2018.09.091

Cited by 100 publications

(22 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, it was found that a larger embedded steel rebar (namely, a higher steel reinforcing ratio) appeared to reduce the peak tensile strength of the HSHUHPC. By contrast, there are instances where conflicting results on the tension-stiffening response of reinforced UHPC are reported by Hung et al [11]. This might be because with a larger diameter of the steel rebar, although the contact area between the steel rebar and UHPC increases, the probability of discontinuous distribution of the steel fiber at the interface between the steel rebar and UHPC is greater, and despite the presence of autogenous shrinkage of UHPC, the bond interaction at the interface between the steel rebar and UHPC is weaker.…”

Section: Tension-stiffening Effectmentioning

confidence: 88%

“…Recently, the rehabilitation of a concrete bridge deck or orthotropic steel deck was widely conducted by employing a thin reinforced UHPC overlay, instead of a relatively thicker reinforced concrete layer, because the demand to upgrade the load-bearing capacity of bridge structures is rising [10,11]. In these scenarios, the thin reinforced UHPC layer is often cast in a state of cyclic tensile stress on the negative moment region, which is subjected to repeating wheel loads, and the thin reinforced UHPC layer behaves as a direct tension member, as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Cyclic Behavior of Reinforced High Strain-Hardening UHPC under Axial Tension

Wang

Yi-qing

2021

Materials

View full text Add to dashboard Cite

The cyclic tensile behavior of steel-reinforced high strain-hardening ultrahigh-performance concrete (HSHUHPC) was investigated in this paper. In the experimental program, 12 HSHUHPC specimens concentrically placed in a single steel reinforcement under cyclic uniaxial tension were tested, accompanied by acoustic emission (AE) source locating technology, and 4 identical specimens under monotonic uniaxial tension were tested as references. The experimental variables mainly include the loading pattern, the diameter of the embedded steel rebar, and the level of target strain at each cycle. The tensile responses of the steel-reinforced HSHUHPC specimens were evaluated using multiple performance measures, including the failure pattern, load–strain response, residual strain, stiffness degradation, and the tension-stiffening behavior. The test results showed that the enhanced bond strength due to the inclusion of steel fibers transformed the failure pattern of the steel-reinforced HSHUHPC into a single, localized macro-crack in conjunction with a sprinkling of narrow and closely spaced micro-cracks, which intensified the strain concentration in the embedded steel rebar. Besides, it was observed that the larger the diameter of the embedded steel rebar, the smaller the maximum accumulative tensile strain under cyclic tension, which indicated that the larger the diameter of the embedded steel rebar, the greater the contribution to the tensile stiffness of steel-reinforced HSHUHPC specimens in the elastic–plastic stage. In addition, it was found that a larger embedded steel rebar appeared to reduce the tension-stiffening effect (peak tensile strength) of the HSHUHPC. Moreover, the residual strain and the stiffness of the steel-reinforced HSHUHPC were reduced by increasing the number of cycles and finally tended toward stability. Nevertheless, different target strain rates in each cycle resulted in different eventual cumulative tensile strain rates; hence the rules about failure pattern, residual strain, and loading stiffness were divergent. Finally, the relationship between the accumulative tensile strain and the loading stiffness degradation ratio under cyclic tension was proposed and the tension-stiffening effect was analyzed.

show abstract

Section: Tension-stiffening Effectmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Cyclic Behavior of Reinforced High Strain-Hardening UHPC under Axial Tension

Wang

Yi-qing

2021

Materials

View full text Add to dashboard Cite

show abstract

“…The results of uniaxial tensile tests on R/UHPC members conducted by Hung et al (2019) showed that the high tensile strength of UHPC can contribute substantially to the tensile strength of R/UHPC. The inclusion of a 2% V f of hook-ended steel fibers (30-mm-long) enhanced the tensile strength of the R/UHPC members with a longitudinal reinforcing ratio ρ l ¼ 0.9%-2.3% by 50%-100%.…”

Section: R/uhpc Tensile Membersmentioning

confidence: 99%

A Review of Developments and Challenges for UHPC in Structural Engineering: Behavior, Analysis, and Design

2021

Self Cite

View full text Add to dashboard Cite

The number of studies on ultrahigh-performance concrete (UHPC) or ultrahigh-performance fiber-reinforced concrete (UHP-FRC) for more resilient and sustainable reinforced concrete (RC) structures has rapidly increased in recent years due to the superior mechanical and durability properties of UHPC. The application of UHPC as a replacement for conventional concrete materials in various RC elements necessitates a thorough understanding of the structural behavior of the reinforced UHPC (R/UHPC) components under various types of loadings. This paper presents a systematic review of the state-of-the-art developments in R/UHPC elements. It addresses various topics including beams, columns, beam-column joints, shear walls, bridges, structural retrofitting, and applications such as seismic and impact. Due to the ultrahigh tensile, compressive, and bond strengths, unique strain-hardening behavior, and ductility of UHPC, R/UHPC structures may exhibit substantially different behavior than conventional RC structures at both the component and system levels. This implies that particular attention must be paid when design and analysis approaches for conventional RC elements are applied to R/UHPC elements, and suggests that developing new design philosophies is warranted to take advantage of UHPC's unique mechanical properties. The present paper summarizes the developments in analysis and design approaches for R/UHPC elements under axial forces, shear forces, and bending moments, and highlights the advantages and limitations of these approaches. Important design considerations for effectively utilizing UHPC in structural elements are also suggested. In addition to normal-strength steel reinforcing bars, the potential for reinforcing UHPC with high-strength steel bars, fiber-reinforced polymer components, and structural steel shapes is discussed based on the results of pioneering studies. Finally, this paper identifies challenges and suggests future directions for research on UHPC in structural engineering.

show abstract

“…Zanuy and Ulzurrun [ 25 ] have proposed a formulation for the tension chord of RC-HPFRC beams with tensile strengthening, but so far, no specific tests have been reported to understand the composite response of RC-HPFRC tension members. Recently, some authors tested reinforced HPFRC tension members, showing that the high tensile strength and strain-hardening capacity of HPFRC lead to improved stiffness, first cracking strength and reduced crack widths than comparative RC members with reinforcing ratios of 0.8–2.5% [ 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Composite Behavior of RC-HPFRC Tension Members under Service Loads

2020

View full text Add to dashboard Cite

A significant increase of the use of high-performance fiber-reinforced concrete (HPFRC) to strengthen reinforced concrete structures (RC) has been noted for the past few years, thereby achieving composite RC-HPFRC elements. Such a technique tries to take advantage of the superior material properties of HPFRC in the ultimate and service load regimes. Many of the existing works on RC-HPFRC elements have focused on the strength increase at the ultimate load state and much less effort has been devoted to the serviceability response. The in-service performance of RC structures is governed by the behavior of the tension chord, which determines the crack pattern (crack widths are critical for durability) and deformations. The presence of HPFRC is supposed to improve serviceability due to its strain-hardening and tension-softening capacities. In this paper, the experimental analysis of composite RC-HPFRC tension members is dealt with. Specimens consisting of a RC tie strengthened with two 35 mm thick HPFRC layers have been subjected to loads in the service range so that the deformational and cracking response can be analyzed. The HPFRC has been a cement-based mortar with 3% volumetric amount of short straight steel fibers with a compressive and tensile strength of 144 MPa and 8.5 MPa, respectively. The experiments have shown that RC-HPFRC has higher stiffness, first cracking strength and reduced crack widths and deformations compared to companion unstrengthened RC. To understand the observed behavioral stages, the experimental results are compared with an analytical tension chord model, which is a simplified version of a previous general model by the authors consisting of 4 key points. In addition, the influence of time-dependent shrinkage has been included in the presented approach.

show abstract

Tension-stiffening effect in steel-reinforced UHPC composites: Constitutive model and effects of steel fibers, loading patterns, and rebar sizes

Cited by 100 publications

References 45 publications

Cyclic Behavior of Reinforced High Strain-Hardening UHPC under Axial Tension

Cyclic Behavior of Reinforced High Strain-Hardening UHPC under Axial Tension

A Review of Developments and Challenges for UHPC in Structural Engineering: Behavior, Analysis, and Design

Composite Behavior of RC-HPFRC Tension Members under Service Loads

Contact Info

Product

Resources

About