This study examines the flexural behavior of reinforced concrete (RC) one-way slabs strengthened with near-surface mounted (NSM) basalt fiber-reinforced polymer (BFRP) bars. Ten RC slabs were ...subjected to four-point loading until failure. Various parameters including the steel reinforcement ratio (0.48and 0.95%), the NSM-BFRP reinforcement ratio (0.17, 0.25, and 0.35%), and two types of epoxy adhesives (Sikadur-30 and NSM-Gel) were investigated. The experimental results demonstrated the remarkable efficacy of the NSM-BFRP bars in enhancing the flexural performance of the strengthened slabs, especially those with lower steel reinforcement ratios. Compared to the control slabs, the ultimate loads were increased by 51‐123% and 21‐44% for slabs with 0.48 and 0.95% steel reinforcement ratios, respectively, while the ductility indices were increased by 10‐53% and 29‐79%. The type of the epoxy adhesive used had minimal impact on the flexural behavior of the strengthened slabs. Failure primarily occurred due to steel yielding followed by the rupture of the NSM-BFRP bars or by concrete crushing, depending on the reinforcement ratio provided. The cracking, yield, and ultimate loads of the strengthened slabs were predicted using the formulations of ACI 440.2R 3 guideline. Good agreement between the predicted and the experimental results were obtained, with ACI formulations being on the conservative side.
•NSM-BFRP increased slab load capacity by up to 124%.•Effectiveness of NSM-BFRP varied based on steel reinforcement ratios.•Strengthened slabs exhibited improved ductility with ductility indices increasing up to 79%.•Failure modes differed based on both steel and NSM-BFRP reinforcement ratios.•Experimental results aligned well with ACI 440.2 R (2017) predictions.
An experimental program was carried out to investigate the behavior of RC beams flexurally strengthened using the NSM technique with CFRP laminates. Four beams were tested, a reference beam without ...CFRP, and three beams flexurally strengthened using different percentage of laminates. The experimental results show that NSM CFRP laminates is an effective solution to increase cracking, yielding and maximum loads of beams failing in bending. Furthermore, the high tensile strength of the CFRP was effectively mobilized. By increasing the CFRP percentage, the load carrying capacity of the NSM beams increased, while the ductility level decreased. Taking into account the experimental results, the predictive performance of the analytical formulation proposed by the ACI was assessed considering two methodologies to determine the maximum strain that can be applied to the CFRP: i) the ACI proposal; ii) the equation proposed by Barros et al. (2007). ACI formulation provides safe results by using both methodologies, but the Barros et al. equation ensures better predictions. A numerical strategy was used to evaluate the load–deflection relationship of the tested beams and to highlight the influence of the longitudinal bars percentage, the CFRP percentage and the concrete strength on the NSM flexural strengthening effectiveness of RC beams.
•A review on the bond behavior of FRP NSM systems in concrete was presented.•A database of pullout tests with FRP NSM systems in concrete was gathered, presented and analyzed.•Database was used to ...evaluate the accuracy of ACI 4402R-08 and HB 305-2008.•The results showed that both guidelines’ formulations need to be upgraded.
This paper presents a review of current knowledge on the bond behavior of fiber reinforced polymer (FRP) systems inserted in the cover of concrete elements, commonly known as the near-surface mounted technique (NSM). In the first part, by studying the physics of the phenomenon, the typical failure modes, the most common bond tests and two of the most important design guidelines for FRP NSM systems are introduced. In the second part, a database of bond tests composed by 431 records is presented and the accuracy of existing design guidelines is assessed with this data. Lastly, the formulations proposed by these design guidelines are recalibrated based on the experimental results in the database.
•Cyclic behavior of pre-damaged RC columns with deficient lap splice strengthened or retrofitted with UHPC and NSM was investigated.•The seismic performance of RC columns was significantly improved ...after strengthening or retrofitting with UHPC and NSM.•The design method addressing the pre-damage effect predicts well the flexural strength of RC columns and beams strengthened with UHPC.
Reinforced concrete (RC) columns with deficient lap splice details such as short lap splice length and widely spaced stirrups were vulnerable to earthquakes. In the present study, to evaluate the effectiveness of an innovative retrofitting technique using the combination of ultra-high performance concrete (UHPC) and near surface mounted (NSM) technique on the seismic performance of RC columns with deficient lap splices details, cyclic loading tests were performed on four large-sized RC column specimens. Two RC columns were strengthened with UHPC or the combination of UHPC and NSM, and the other two were retrofitted with the combination of UHPC and NSM after the lateral strength decreased to 85% peak strength during the pre-damage cyclic tests. The load–displacement relationship, stiffness degradation, energy dissipation, and residual displacement of RC columns are evaluated. The test results showed that the peak strength and ductility of RC columns with deficient lap splice are significantly improved after strengthening or retrofitting with the combination of UHPC and NSM. The seismic performance of severely damaged RC columns due to deficient lap splice details can still be effectively restored after retrofitting with the combination of UHPC and NSM. Considering the adverse effect of pre-damage, a design method is proposed to predict the flexural capacity of RC columns retrofitting with UHPC or the combination of UHPC and NSM. The proposed method is also applied to predict the flexural capacity of RC beams strengthened with UHPC. The proposed method predicted well the test results of this study and existing tests.
•Degradation of local bond strength of FRP-to-concrete bonded joints subject to direct pull-out fatigue loading is investigated.•Effect of various parameters on fatigue bond behavior and life is ...considered.•Higher fatigue load ranges accelerated local bond degradation drastically leading to a much shorter fatigue life of bonded joints.
The interfacial bond characteristics and failure mechanism of near-surface mounted (NSM) fiber reinforced polymer (FRP) composites in concrete under fatigue loading are less understood compared to their bond behavior under static loading. In this paper, degradation of the local bond strength of FRP-to-concrete bonded joints subjected to direct pull-out fatigue loading is presented for both carbon FRP (CFRP) rods and strips under different fatigue load ranges, i.e., 10–50%, 10–60%, and 10–70%, of the corresponding static load-carrying capacity. The interfacial debonding between FRP and adhesive was observed during fatigue cycles for CFRP rod specimens to different extents. Specimens using CFRP rods with sand-coated and spirally wound surface treatment presented a higher local bond strength and a slower degradation rate, as compared to the ones using CFRP rods with roughened or sand-coated treatment. Using epoxy adhesives with higher strengths benefitted the fatigue bond performance of the tested specimens in terms of local bond strength and stable behavior. Higher fatigue load ranges substantially accelerated the local bond degradation resulting in a much shorter fatigue life of the bonded joints.
The preliminary findings of cyclic tests conducted on a series of half-scale unstrengthened and strengthened masonry walls are presented. Reinforced walls were strengthened by (i) non-prestressed ...near surface mounted (NSM) glass fibre reinforced polymer (GFRP) bars and (ii) prestressed NSM GFRP. Walls were strengthened symmetrically by vertical bars passing through both mortar and bricks. The structure was subjected to concurrent sustained uniformly distributed vertical loads and static cyclic horizontal loads. Each reinforcement method was evaluated for its loading capability and ductility efficiency. The experimental results showed a considerably higher ultimate load-carrying capability and ductility of strengthened walls compared to the unstrengthened wall. This was more pronounced for walls reinforced with prestressed GFRP bars. The ultimate strength of the strengthened walls compared to the un-reinforced masonry (USM) wall was 38% for the wall strengthened with the non-prestressed NSM technique and 58% for the wall strengthened with the prestressed NSM technique. The horizontal failure displacement was improved by about 64% in the non-prestressed NSM technique and 127% in the prestressed NSM technique compared to the USM wall.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Author 1 Given name: Hossein Kanani Last name kashani. Also, kindly confirm the details in the metadata are correct. Author 4 Given name: Seyed Mohammad Last name Hosseini. Also, kindly confirm the details in the metadata are correct. Author 5 Given name: Seyed Mohammad Reza Last name Mortazavi. Also, kindly confirm the details in the metadata are correct.All confirmed!Please check and confirm the corresponding affiliation is correctly identified.Confirmed!
•NSM application using CBA and CFRP improved the shear capacity of the RC members.•When CFRP textile was used in combination with the CBA, CFRP rupture was observed.•CBA achieved comparable results ...to epoxy when used with CFRP textile.•Using CBA with CFRP textile is considered a good substitute for epoxy resins.
The shear strength of existing Reinforced concrete (RC) members can be improved by bonding Carbon fibre reinforced polymers (CFRPs) as Near-surface mounted (NSM) or Externally bonded reinforcement (EBR). CFRPs are typically bonded to RC members using epoxy resins which have low glass transition temperatures resulting in poor fire performance. In an effort to improve the fire performance of CFRP strengthened members, researchers have developed Cement-based adhesives (CBAs) and verified their efficacy using NSM CFRP-to-concrete joint tests, however no applications have been conducted on full-scale RC beams strengthened in shear using NSM CFRP and CBA. This study attempts to fill this gap and involves testing fourteen RC beams strengthened in shear using NSM CFRP textile bonded using CBA. The experimental results showed that CFRP textile bonded using CBA in NSM configurations significantly improved the shear capacity of the RC members. Further, comparisons were made between CBA and epoxy resins as bonding agents and it was found that CBA achieved comparable results to epoxy when used in the configuration explored. The results of NSM-CFRP strengthened beams with CBA showed shear strength improvements of 97% and 70% using CFRP textile and laminate, respectively. Therefore, the use of CBA in the NSM CFRP strengthening techniques is considered a good substitute for epoxy resins for bonding CFRP to concrete members.
The objective of this investigation is to assess the effectiveness of hybrid fiber reinforced polymer (FRP) strengthening on the overall behavioral improvement of reinforced concrete (RC) beams under ...flexure. Eight square RC beams were cast and strengthened using different FRP techniques including (i) near surface mounting (NSM), (ii) external bonding (EB) and (iii) hybrid strengthening using a combination of NSM carbon FRP laminates and EB CFRP fabric. Peak moment capacity was calculated analytically by enforcing the sectional equilibrium using the strain compatibility procedure. A micro plane based nonlinear three-dimensional finite element (FE) model was developed to simulate the behavior of the RC beams with and without FRP strengthening. Experimental results revealed that hybrid FRP strengthening could increase the strength by 160%. Moreover, the ultimate displacement of hybrid FRP strengthened beams improved significantly when compared to only the NSM technique. Only NSM strengthening improved the peak strength by 85% but had a brittle bond failure. Only EB strengthening improved the ductility of the flexural members due to confinement but did not significantly increase the strength. Predictions of the FE model correlated well with the experimental results and revealed that minimum edge distance for NSM laminates has to be ensured for preventing premature edge de-bonding failures.
This research explores basic and secondary colors in Indonesia. This research attempts to explicate the meaning of colors by using the semantic theory of Natural Semantic Metalanguage Theory. This ...research applied qualitative method. The paradigm of qualitative research revolves around the observation from the surrounding. The data were collected from various sources such as Indonesian Dictionary, Indonesian Corpus, and the data created by the researcher as the native speaker. The researcher explicates primary or basic colors as well as the secondary. Further, these Indonesian colors were being explicated by applying the features of Natural Semantic Metalanguage (NSM). The colors in Indonesian were gathered and classified. The researcher then analyzed the colors based on the explication of NSM theory and the approach of Basic Color Term initiated by Berlin and Kay. This research discovers that the basic or primary colors in Indonesian are Black, White, Red, Yellow, Green and Blue. The application of this research is apparently vivid in the advancement of colors study in the realm of semantics. This research also exposes the difference of explication in English and Indonesian. This occurred due to the difference of the usage of semantic atom to explain the meaning of color. To explicate the color of black, Indonesian uses charcoal. Meanwhile English uses the night sky. In Indonesian, colors that come after Green and Blue according to Berlin and Kay’s color terms are Brown, Purple, Orange, Pink, and Grey are not basics but secondary colors. Meanwhile, in English the aforementioned colors are basics.
This research explores basic and secondary colors in Indonesia. This research attempts to explicate the meaning of colors by using the semantic theory of Natural Semantic Metalanguage Theory. This ...research applied qualitative method. The paradigm of qualitative research revolves around the observation from the surrounding. The data were collected from various sources such as Indonesian Dictionary, Indonesian Corpus, and the data created by the researcher as the native speaker. The researcher explicates primary or basic colors as well as the secondary. Further, these Indonesian colors were being explicated by applying the features of Natural Semantic Metalanguage (NSM). The colors in Indonesian were gathered and classified. The researcher then analyzed the colors based on the explication of NSM theory and the approach of Basic Color Term initiated by Berlin and Kay. This research discovers that the basic or primary colors in Indonesian are Black, White, Red, Yellow, Green and Blue. The application of this research is apparently vivid in the advancement of colors study in the realm of semantics. This research also exposes the difference of explication in English and Indonesian. This occurred due to the difference of the usage of semantic atom to explain the meaning of color. To explicate the color of black, Indonesian uses charcoal. Meanwhile English uses the night sky. In Indonesian, colors that come after Green and Blue according to Berlin and Kay’s color terms are Brown, Purple, Orange, Pink, and Grey are not basics but secondary colors. Meanwhile, in English the aforementioned colors are basics.
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