Experimental investigation of the mechanical connection between FRP laminates and concrete

Realfonzo, Roberto; Martinelli, Enzo; Napoli, Annalisa; Nunziata, Bruno

doi:10.1016/j.compositesb.2012.05.010

Cited by 36 publications

(18 citation statements)

References 16 publications

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“…This issue is of great importance, as can be attested to by the numerous researches found in the literature (Biscaia et al 2014;Mendes 2008;Martinelli et al 2012;Breña and McGuirk 2013;Realfonzo et al 2013;Wu and Liu 2013) seeking for a valid and alternative solution for enhancing the strength of EBR systems. Still, it is important to bear in mind that the use of steel mechanical fasteners involves making a hole on the SS strip which may lead to an important setback due to the reduction of the SS cross section of the strip to install the fasteners.…”

Section: Definition Of the Effective Bond Lengthmentioning

confidence: 99%

Stainless Steel Bonded to Concrete: An Experimental Assessment using the DIC Technique

Biscaia

Franco

Chastre

2018

Int J Concr Struct Mater

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The durability performance of stainless steel makes it an interesting alternative for the structural strengthening of reinforced concrete. Like external steel plates or fibre reinforced polymers, stainless steel can be applied using externally bonded reinforcement (EBR) or the near surface mounted (NSM) bonding techniques. In the present work, a set of single-lap shear tests were carried out using the EBR and NSM bonding techniques. The evaluation of the performance of the bonding interfaces was done with the help of the digital image correlation (DIC) technique. The tests showed that the measurements gathered with DIC should be used with caution, since there is noise in the distribution of the slips and only the slips greater than one-tenth of a millimetre were fairly well predicted. For this reason, the slips had to be smoothed out to make it easier to determine the strains in the stainless steel and the bond stress transfer between materials, which helps to determine the bond-slip relationship of the interface. Moreover, the DIC technique allowed to identify all the states developed within the interface through the load-slip responses which were also closely predicted with other monitoring devices. Considering the NSM and the EBR samples with the same bonded lengths, it can be stated that the NSM system has the best performance due to their higher strength, being observed the rupture of the stainless steel in the samples with bond lengths of 200 and 300 mm. Associated with this higher strength, the NSM specimens had an effective bond length of 168 mm which is 71.5% of that obtained for the EBR specimens (235 mm). A trapezoidal and a power functions are the proposed shapes to describe the interfacial bond-slip relationships of the NSM and EBR systems, respectively, where the maximum bond stress in the former system is 1.8 times the maximum bond stress of the latter one.

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Section: Definition Of the Effective Bond Lengthmentioning

confidence: 99%

Stainless Steel Bonded to Concrete: An Experimental Assessment using the DIC Technique

Biscaia

Franco

Chastre

2018

Int J Concr Struct Mater

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“…Figure 6, instead, shows the bearing stress-interface slip (σ f -s) relationships employed to simulate the response of the connecting devices, i.e., of shot or screwed fasteners. In particular, the trilinear laws selected in the case of screws with (w/) and without (w/o) washers (Models 2b and 3 in Figure 6) are those proposed by the authors in a previous study [16]; the other ones, used in the case of shot or screwed fasteners w/ washer (Models 1 and 2a in Figure 6), are those found by Elsayed et al [17]. It is highlighted that although three of the four σ f -s laws exhibit a softening branch, the actual values of the interfacial slip observed in the modeling of the MF-FRP-strengthened beams never fall in such a branch; therefore, modeling issues related to strain localization can be overcome.…”

Section: Nonlinear Analysis Proceduresmentioning

confidence: 99%

“…As mentioned earlier, Elsayed et al [17] and Realfonzo et al [16] recently proposed nonlinear bearing stress-slip models to describe the effect of the partial interaction between the concrete and the FRP laminate. These models, depicted in Figure 6, were experimentally calibrated through direct shear (DS) tests performed on MF-FRP/concrete joints with a single connector.…”

Section: Influence Of the Bearing Stress-slip Interface Lawmentioning

confidence: 99%

“…In Figure 9e-h, the behavior of screws w/o washer in tests by Napoli et al [11] was modeled by using Model 3 in Figure 6 by Realfonzo et al [16] and, for comparison, Model 1 by Elsayed et al [17], though suitable for fasteners w/ washer. Furthermore, in order to better highlight how the use of a proper bearing stress-slip law improves the fitting of the experimental results, in Figure 9g,h the results of numerical simulations obtained by implementing a "no-slip" model of the MF-FRP connection are reported.…”

Section: Influence Of the Bearing Stress-slip Interface Lawmentioning

confidence: 99%

“…In this test, the behavior of the FRP-concrete interface was modeled through the σ f -s law proposed by Realfonzo et al [16] and suitable for fasteners w/o washers (i.e., Model 3 in Figure 6); the tension stiffening effect was taken into account by considering C = 1 in Equation (6). As shown, the post-yield behavior of the experimental curve is better simulated by considering f y = 475 MPa in the numerical analysis, whereas no appreciable influence is noted by changing the stress-strain model for steel rebars.…”

Section: Trilinear Model Trilinear Modelmentioning

confidence: 99%

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RC Beams Strengthened with Mechanically Fastened Composites: Experimental Results and Numerical Modeling

et al. 2014

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Abstract:The use of mechanically-fastened fiber-reinforced polymer (MF-FRP) systems has recently emerged as a competitive solution for the flexural strengthening of reinforced concrete (RC) beams and slabs. An overview of the experimental research has proven the effectiveness and the potentiality of the MF-FRP technique which is particularly suitable for emergency repairs or when the speed of installation and immediacy of use are imperative. A finite-element (FE) model has been recently developed by the authors with the aim to simulate the behavior of RC beams strengthened in bending by MF-FRP laminates; such a model has also been validated by using a wide experimental database collected from the literature. By following the previous study, the FE model and the assembled database are considered herein with the aim of better exploring the influence of some specific aspects on the structural response of MF-FRP strengthened members, such as the bearing stress-slip relationship assumed for the FRP-concrete interface, the stress-strain law considered for reinforcing steel rebars and the cracking process in RC members resulting in the well-known tension stiffening effect. The considerations drawn from this study will be useful to researchers for the calibration of criteria and design rules for strengthening RC beams through MF-FRP laminates.

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Analytical model for concrete cover separation of FRP strengthened RC beams with multiple steel bolts

Zhang

Shi

Zhu

et al. 2020

Structural Concrete

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In this paper, analytical models for concrete cover separation (CCS) of FRP strengthened reinforced concrete (RC) beams with multiple steel bolts were developed based on concrete tooth model for strengthened RC beams without anchors. The derivation of the models involved three major steps: (a) determination of the crack spacing (width of the concrete teeth); (b) determination of the pull‐out strength of steel bolt considering the effect of shear crack; and (c) determination of the peak load of FRP strengthened beams when CCS occurs based on the concrete tooth model. Validation test on five RC beams was conducted to investigate the effect of anchorage systems on the premature debonding of FRP strengthened RC beams. Results showed that steel bolts with enough embedding length can effectively suppress the initiation and propagation of CCS, thus improve the performance of FRP strengthened RC beams. Moreover, a database of FRP strengthened RC beams with mechanical fasteners (MFs) and failed in CCS or FRP fracture (FR) was assembled from the literature. The analytical predictions agreed well with the experimental results.

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Experimental investigation of the mechanical connection between FRP laminates and concrete

Cited by 36 publications

References 16 publications

Stainless Steel Bonded to Concrete: An Experimental Assessment using the DIC Technique

Stainless Steel Bonded to Concrete: An Experimental Assessment using the DIC Technique

RC Beams Strengthened with Mechanically Fastened Composites: Experimental Results and Numerical Modeling

Analytical model for concrete cover separation of FRP strengthened RC beams with multiple steel bolts

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