Shear performance of basalt fiber-reinforced concrete beams reinforced with BFRP bars

doi:10.1016/j.compstruct.2022.115443

Composite Structures

Volume 288, 15 May 2022, 115443

https://doi.org/10.1016/j.compstruct.2022.115443 Get rights and content

Abstract

This paper reports on the experimental and analytical investigation of the shear performance of concrete beams cast with basalt fiber-reinforced concrete (BFRC) and longitudinally reinforced with basalt fiber-reinforced polymer (BFRP) bars. Fourteen hybrid (BFRC-BFRP) beams with no stirrups were tested to failure under a four-point loading setup. The investigated parameters included the volume fraction, V_f, of the added fibers (0.75 and 1.5%), the reinforcement ratio of the BFRP bars, $ρ$ , (0.31, 0.48, 0.69, 1.05, and 1.52%), and the shear span-to-depth ratios, a/d, of the beams (3.3 and 2.5 for slender and short beams, respectively). The tests results showed that adding 0.75% of basalt macrofibres (BMF) improved the shear capacity of the slender and short beams by 46 and 43 %, respectively, compared to 81 and 82% when 1.5% of BMF were added. The impact of adding the BMF on the shear strength of the beams diminished as the longitudinal reinforcement ratios increased. The existing models overestimated the shear strength of the tested beams with an average predicted-to-experimental ratio ranging between 1.15 ± 0.03 and 2.48 ± 0.29. A shear model that accounts for the type of the longitudinal reinforcement and the added fibers was proposed to predict the shear strength of the BFRC-BFRP beams. A good agreement between the predicted and experimental shear strength was evident with a predicted-to-experimental ratio that ranged between 0.98 ± 0.11 and 0.88 ± 0.02 for the slender and short beams, respectively.

Section snippets

Introduction and background

Reinforced concrete (RC) beams develop their shear strength through a well-established mechanism that involves friction forces, compressive forces, and aggregate interlocking over the tension-shear cracks. Beside those governing parameters, the dowel action of the reinforcing bars, which develops as the shear crack grows and cuts across the bars, is a major contributor to the shear strength, particularly in beams with no stirrups provided. Typically, as the longitudinal reinforcement ratio, $ρ$ ,

Research program

The experimental program consisted of fourteen RC beams as shown in Table 1. Two groups of beams (A and B) were tested according to their a/d ratios. All beams were reinforced with reinforcement ratios, ρ, greater than the balanced reinforcement ratio, ρ_b, as recommended by the CAN/CSA-S806-12 [8] code and the ACI-440.1R-15 [6] guidelines. Beams of group A were reinforced with five different ratios, ρ, namely; 1.09 ρ_b, 1.69 ρ_b, 2.43 ρ_b, 3.69 ρ_b, and 5.35 ρ_b with a span-to-depth ratio, a/d, of

Crack pattern and failure mode

The crack patterns for beams of groups A and B are illustrated in Fig. 5 (a) and (b), respectively. Initially, flexural cracks were formed at midspan and propagated progressively upwards towards the extreme compression zone. As the applied load increased, the flexural cracks increased in width and height while new cracks were formed. When the applied loads were further increased, diagonal cracks were formed along the shear span and extended towards the loading points until failure occurred. All

Predicting the shear capacity of the tested beams

To estimate the shear capacity of the tested beams, three models were used, namely; the models developed by Gandomi et al. [33], Dinh et al. [34], and Arslan [35]. The formulations of each model are summarized in Table 5. It can be observed that each model incorporates several parameters that are known to contribute differently to the shear capacity of RC beams. Those parameters include the a/d ratio, the reinforcement ratio, $ρ$ , the fiber bond factor, d_f, the fiber pull-out strength, v_b, the

Conclusions and recommendations

In this study, the shear performance of concrete beams reinforced longitudinally with BFRP bars and cast with BFRC mixes incorporating basalt macro-fibers (BMF) was investigated. The experimental shear capacity of the tested beams were predicted using the formulations of existing models, which were developed to predict the shear capacity of steel-reinforced beams cast with SFRC mixes. A model that considered the type and amount of both the longitudinal reinforcement and the added fibers was

CRediT authorship contribution statement

Ahmed El Refai: Conceptualization, Methodology, Validation, Writing – review & editing, Supervision. Wael Alnahhal: Conceptualization, Methodology, Validation, Writing – review & editing, Resources, Funding acquisition, Supervision, Project administration. Abathar Al-Hamrani: Investigation, Formal analysis, Writing – review & editing, Data curation, Software. Sarah Hamed: Investigation, Formal analysis, Visualization.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgment

The authors would like to express their appreciation to the Qatar Foundation for their financial assistance through UREP award no. UREP21-089-2-039 and GSRA grant no. GSRA6-1-0301-19005 from the Qatar National Research Fund (QNRF, a member of Qatar Foundation).

Data Availability

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

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Shear performance of basalt fiber-reinforced concrete beams reinforced with BFRP bars

Abstract

Section snippets

Introduction and background

Research program

Crack pattern and failure mode

Predicting the shear capacity of the tested beams

Conclusions and recommendations

CRediT authorship contribution statement

Declaration of Competing Interest

Acknowledgment

Data Availability

Eng Struct

Compos Struct

Constr Build Mater

Compos Struct

Compos Struct

Eng Struct

Compos Struct

Eng Struct

Constr Build Mater

Constr Build Mater

Constr Build Mater

Compos PART B

Cem Concr Compos

Shear strength of normal strength concrete beams reinforced with deformed GFRP Bars

J Compos Constr

Shear tests of FRP-reinforced concrete beams without stirrups

ACI Struct J

Shear Behavior of Basalt Fiber Reinforced Concrete Beams with and without Basalt FRP Stirrups

J Compos Constr

Concrete Contribution to Shear Strength of Beams Reinforced with Basalt Fiber-Reinforced Bars

J Compos Constr

Shear strength of GFRP-reinforced concrete continuous beams with minimum transverse reinforcement

J Compos Constr