Josée Bastien’s research while affiliated with University of Quebec and other places

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Publications (42)


Aggregate Interlock and Shear Friction Behaviour of ASR Affected Concrete
  • Chapter

May 2024

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21 Reads

Zakari Nana

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Benoit Fournier

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Julien Walter


Fig. 2 -Shear capacity of shear strengthened members with bonded bars tested by several authors.
Design of concrete members strengthened in shear with vertical bonded bars
  • Conference Paper
  • Full-text available

July 2022

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46 Reads

Due to design using older codes, material degradation and increased traffic loads, numerous reinforced concrete bridge members, such as beams and slabs, have insufficient shear capacity and need shear strengthening. An efficient shear strengthening technique consists of adding drilled-in vertical reinforcing bars within the existing concrete member and to bond these bars to the concrete with high-strength epoxy adhesive. However, the shear design method prescribed by the Canadian Highway Bridge Design Code for members with stirrups may overestimate the shear capacity of shear strengthened members with epoxy-bonded bars. This paper presents the effect of bonded shear reinforcement on shear resistance mechanisms and summarizes a proposed shear design method developed for reinforced concrete members with epoxy-bonded shear reinforcement.

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Influence of Alkali-Silica reaction (ASR) on aggregate interlock and shear-friction behavior of reinforced concrete members

February 2021

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143 Reads

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12 Citations

Engineering Structures

Alkali-silica reaction (ASR) is one of the most damaging mechanisms affecting concrete structures worldwide. ASR effects on the durability and serviceability of damaged concrete are widely known and fairly well understood. However, the structural implications are still unclear, and a number of contradictory data are found in the literature, especially regarding shear behavior. The influence of ASR distressed reinforced concrete on aggregate interlock is presented in this paper. Push-off specimens having different transverse reinforcement ratios were fabricated with ASR reactive coarse aggregates. The specimens were monitored over time and displayed different levels of expansion. Results indicated that ASR-induced expansion and damage were affected by the transverse reinforcement ratio. However, little to no aggregate interlock reduction was observed on ASR-affected specimens up to moderate expansion levels (about 0.12%). It was found that there were two controlling and competing mechanisms that affected aggregate interlock for ASR-affected specimens: the beneficial effects of chemical prestressing and the detrimental ASR-induced damage.


Behavior of Post-Installed Bonded Bars as Shear Reinforcement

July 2020

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107 Reads

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2 Citations

ACI Structural Journal

Post-installed epoxy-bonded shear reinforcement is a promising technique to increase shear capacity of reinforced concrete (RC) structures. However, the behavior of epoxy-bonded bars largely affects the shear strengthening efficiency. To better predict the behavior of epoxy-bonded bars, a bond model is developed in this paper. This model appears to adequately predict the behavior of epoxy-bonded bars observed in experimental pullout tests and beam loading tests. Based on numerical results, a simplified model is proposed to predict the epoxy-bonded bars’ stress according to the crack width. It appears that the behavior of long embedded bars is similar to stirrups in terms of crack width and bar stress. However, a large diagonal crack is required to reach the bar yielding strength when the bar embedment length is below a transition length, which differs from stirrups. Embedment length below the epoxy-bonded bar development length leads to pullout failure and bar capacity lower than the bar yielding strength.


Condition assessment of an ASR-affected overpass after nearly 50 years in service

November 2019

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104 Reads

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47 Citations

Construction and Building Materials

RBC overpass was a highway bridge structure that was built using an alkali-silica reactive aggregate. Over nearly 5 decades, many signs of distress were developed on the various RBC structural members mainly due to alkali-silica reaction (ASR). In 2010/2011, RBC overpass was demolished and thus a number of cores from the various structural members were extracted, which enabled the condition assessment of the structure through a comprehensive multi-level protocol. This paper presents the outcomes obtained from the overall evaluation of RBC members. Results show that the damage degree of the distinct members vary according to the member’s type and condition. Very high, high and moderate damage levels were found for the foundation blocks, bridge deck and columns of the structure, which indicates that RBC overpass was not in accordance with Canadian safety protocols by the time of its demolition and raises concerns regarding the structural implications of ASR-affected infrastructure.



Reliability of Wavelet Analysis of Mode Shapes for the Early Detection of Damage in Beams

July 2019

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599 Reads

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8 Citations

Frontiers in Built Environment

Numerous procedures have been developed for the detection and the localization of damage in structures based on changes in the dynamic or static response of structures. Among these, procedures based on wavelet analysis of mode shapes appear to offer a superior performance especially for low levels of damage. In order to evaluate the relative merit of these approaches, criteria based on statistical and probabilistic performance are evaluated as a function of damage level for an experimental beam. These measures include the probability of detection, the probability of false alarms, and the safety index. The safety index used in this application is for the beam under pure bending, which provides a uniform criteria for damage at any location along the beam. The experimental data is obtained on a steel beam where the level of damage is controlled at two locations along its length. A total of 16 equally spaced accelerometers are deployed along the length of the beam. The dynamic properties used to illustrate the proposed procedure are changes in the frequency of the first mode of vibration of the beam and changes in the wavelet coefficients for the first mode of vibration. The data obtained for 5 increasing level of damage at two locations is used to derive prediction equations for the dynamic properties and to estimate the probability of detection and of false alarms as a function of damage level. The results indicate that the procedure based on wavelets is more efficient than the one based on natural frequencies in detecting and localizing low levels of damage. The results also indicate that a monitoring strategy based on wavelets can detect damage before structural safety is significantly compromised while maintaining low probabilities of false alarms.


Shear strengthening of concrete members with unbonded transverse reinforcement

February 2019

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80 Reads

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12 Citations

Engineering Structures

This paper examines the behaviour of thick concrete members strengthened in shear with unbonded transverse reinforcement. The retrofitting technique consists of placing unbonded vertical bars with steel end plates or torque controlled expansion end anchorages in pre-drilled holes of existing thick members. To study the behaviour of these members, loading tests as well as numerical analyses were carried out. Shear capacities were compared to the predictions using the shear design approach in the Canadian Highway Bridge Design Code. The design equations which are intended for traditional stirrups reinforcement overestimates the shear capacities of the members strengthened with unbonded transverse reinforcement. However, numerical analyses provided very accurate predictions of the shear capacities. A finite element parametric study examines the effects of the shear span-to-depth ratio, vertical prestressing, shear reinforcement ratio and the stiffness of the vertical reinforcement. The stiffness of the shear strengthening system and the effects of prestressing significantly affect the shear capacity. The shear capacities were predicted well when a minimum amount of vertical prestressing was provided.


Figure 1. Shear failure in a thick concrete member (Mitchell et al., 2011)
Figure 2. Shear strengthening with epoxy-bonded reinforcement bars: a) Drilling holes in the slab; b) Cleaning holes; c) Adhesive injection; d) Shear reinforcing bar insertion.
Figure 3. a) Experimental slab specimens; b) Slab submitted to a three-point flexural loading test
Figure 4. a) Slab without transverse reinforcement; b) Slab without transverse reinforcement subjected to service load; c) Strengthened slab at service load; d) Strengthened slab at ultimate load and shear failure
Shear strengthening of thick concrete slabs accounting for loading during strengthening

In order to investigate the effect of the service shear load at the time of strengthening a thick slab using bonded transverse reinforcing bars, an experimental study has been carried out. Five (5) beams representing slices of a thick slab were tested to induce different shear load levels in the beams at the time of strengthening then loaded up to shear failure. Tests were conducted on a slab without shear reinforcement and the others on slabs strengthened at two different load levels at the time of strengthening. The added shear reinforcement was distributed according to two different longitudinal spacings. The results show that, even in the presence of usual service loads, the shear strengthening of thick slabs with bonded bars offers a considerable increase in shear capacity compared to a thick slab without shear reinforcement.


Citations (30)


... As a consequence, the effectiveness of the FRP strengthening techniques is also reduced [51]. Recent research has proposed an innovative approach for shear strengthening of RC beams called embedded through-section (ETS) [52][53][54][55][56][57][58]. During the ETS system's construction, steel or FRP bars are placed into drilled holes in the cross section and then fastened to the concrete substrate using an epoxy resin. ...

Reference:

Shear Strengthening Of Reinforced Concrete Beams Using Various CFRP Techniques
Shear design of RC members strengthened with steel reinforcing bars embedded through section
  • Citing Article
  • June 2023

Engineering Structures

... To overcome this limitation, some researchers suggested to insert drilled-in reinforcing bars and anchor the bars to the concrete with high strength adhesives or mechanical anchorages (Bédard, 2018;Cusson, 2012;Fernández Ruiz et al., 2010;Fiset et al., 2019;Hellberg & Eryd, 2018;Inácio et al., 2012;Provencher, 2010;Valerio et al., 2011). Fig. 1 shows the section of a wide structural thick slab strengthened in shear with bars inserted in drilled holes from the top face of the bridge and anchored with an adhesive. ...

Renforcement à l’effort tranchant des dalles épaisses en béton en conditions de service
  • Citing Poster
  • January 2018

... In the last decade, through laboratory tests on slab samples, the capacity of strengthened slabs with bonded bars was compared to that of slabs with stirrups as well as to slabs without transverse reinforcement (Valerio 2009, Fernández et al 2010, Provencher 2011, Cusson 2012). In addition, the bond behaviour of the adhesive used to anchor the bars was analyzed by Villemure et al. (2015Villemure et al. ( , 2016. For a conventional stirrup, the reinforcement is anchored at its extremities by hooks around longitudinal bars. ...

Study Of Bond Between Epoxy, Steel Reinforcing Bars And Concrete Affected By Alkali-Silica Reaction

... In the last decade, through laboratory tests on slab samples, the capacity of strengthened slabs with bonded bars was compared to that of slabs with stirrups as well as to slabs without transverse reinforcement (Valerio 2009, Fernández et al 2010, Provencher 2011, Cusson 2012). In addition, the bond behaviour of the adhesive used to anchor the bars was analyzed by Villemure et al. (2015Villemure et al. ( , 2016. For a conventional stirrup, the reinforcement is anchored at its extremities by hooks around longitudinal bars. ...

Effet de la réaction alcalis-silice (ras) sur l’adhérence des ancrages époxydiques de barres d’armature

... These techniques are effective in increasing the shear capacity of beams but are much less efficient for wide structural element applications, such as slabs. The embedmentthrough-section (ETS) technique illustrated in Fig. 1a consists of inserting reinforcing bars into pre-drilled holes and anchoring the bars to the concrete with high-strength epoxy adhesive [22][23][24][25][26][27][28][29][30][31][32][33][34]. Fig. 1b illustrates a member shear strengthened with different configurations of reinforcing bars embedded through the section. ...

Renforcement à l’effort tranchant des dalles épaisses en béton armé en conditions de service

... The typical bondslip response of epoxy-bonded bars is presented in Fig. 2a, where s 1 and s 2 are the slips at the peak bond stress, and f b0 is the basic bond strength of the adhesive given by the manufacturer. Typically for properly installed bonded bars, s 1 = 0.8 to 1 mm, s 2 = 2 mm [52][53][54][55]. To consider concrete breakout, the bond strength, f b , is limited as expressed by the following equation [53][54][55]. ...

Thick concrete slab bridges: study of shear strengthening

... On the other hand, conventional stirrups are considered fully anchored and fully active. Thus, the contribution to shear capacity of bonded bars are typically lower than the contribution of stirrups (Fiset et al., 2014). 137-4 Fig. 3c presents the crack width, w, measured at the member mid-height for members with bonded bars and with stirrups. ...

Experimental And Analytical Studies Of Strengthening Using Drilled-In Bonded Shear Reinforcement

... In the literature, different strengthening methods are proposed, for example methods with: epoxybonded internal steel bars, 1 external shear reinforcement 2 and post-installed reinforcement. 3,4 Since this specific bridge will serve an electrically driven tram, electrical insulation was required. Therefore, the bridge was strengthened with post-installed, prestressed vertical steel bars. ...

Behaviour of thick concrete members with unbonded transverse reinforcement

... By comparing this method with other post-installed shear strengthening methods [1,2,3,4] for narrow beams elements, the proposed method has the advantage to be fully effective on wide and thick elements such as slabs. Two series of tests performed on thick slabs were conducted up to shear failure [5,6,7]. Results showed that while shear-strengthened slabs can exhibit failure loads 46% higher than original unstrengthened slabs, they showed failure loads 29% lower than the fib model code 2010 and CAN-CSA S6-06 code prediction values [8,9]. ...

Post-installed shear reinforcement for concrete thick slabs

... Several experiments [9][10][11] have been conducted to investigate the mechanical properties of ASR-damaged concrete under stress confinement. Fiset et al. [12] conducted a series of experiments to investigate the influence of ASR-distressed RC on aggregate interlock, revealing that chemical prestressing yields beneficial effects, while ASR-induced damage adversely affects aggregate interlock in affected specimens. Consistent with their previous research [13], pullout tests were conducted on specimens exhibiting varying levels of ASR expansion to quantitatively assess its impact on bond performance in reinforced concrete, revealing that ASR can enhance bond performance at relatively low volumetric expansion rates. ...

Influence of Alkali-Silica reaction (ASR) on aggregate interlock and shear-friction behavior of reinforced concrete members
  • Citing Article
  • February 2021

Engineering Structures