1,720,969 research outputs found
Bond of GFRP bar and concrete: numerical approach
No full textCurrent practice of FRP (Fibre Reinforced Polymer) RC (Reinforced Concrete) structures mainly takes perfect bond as an assumption for modelling the structural behaviour. As distinct to that, present work deals with application of local bond-slip law for estimating the influence of the interaction of FRP bar and concrete at structural level. For this purpose, the investigation involves two scales. Small scale (pull-out test specimens) and full-scale (reinforced concrete beams) are considered for assessment of numerical models. 3D finite element (FE) model was developed to consider the non-linear behaviour of the interface, as well as of the concrete, using the commercial software Abaqus1. The bond interface properties were simulated considering the secant modulus-based damage evolution law using cohesive elements. The developed bond model, validated by pull-out tests, were subsequently adopted for the numerical predictions of the mechanical response of full-scale beams. The model showed great potential to simulate the behaviour of structural element reinforced with such FRP materials, particularly at ultimate loading level
Experimental measurements and numerical modelling of bond between GFRP bars and concrete
No full textThe paper focuses on the numerical simulation of the bond between GFRP bar and concrete under static loading. Experimental eccentric pull-out tests were considered for the assessment, accounting for the influence of low concrete cover as in real structural components. 3D non-linear finite element (FE) model was adopted and validated considering the bond shear stress vs. slip behaviour and the damage patterns observed experimentally. The bond interface properties were simulated using cohesive elements by adopting the bond damage evolution approach, which consisted of two damage evolution laws: the exponential softening branch and secant modulus-based model. Bond damage models predict damage parameter evolutions close to each other and were both used for the 3D numerical simulation of the complete bonding behaviour
Modeling the bond of GFRP and concrete based on a damage evolution approach
No full textThe effect of debonding of glass-fiber-reinforced-polymer (GFRP) reinforcing bar on progressive collapse resistance of concrete structures is an important point in the design of GFRP reinforced concrete structures. Due to the complexity of the GFRP-concrete debonding failure, numerical analyses are necessary to better understand the influence of several parameters on this failure mode. Hence, the current paper aims to develop a 3D finite-element (FE) model, capable of predicting the debonding failure by modeling the GFRP bar-concrete bond interface using cohesive elements. The damage assessment approach is adopted to determine the properties of the bond interface. Moreover, the model considers the nonlinear behavior of concrete. At the end, the good predictive performance of the developed FE model is demonstrated by comparing with the relevant experimental results
Experimental investigation of the static bond of GFRP rebar and concrete
No full textThis paper presents an experimental investigation dealing with the quasi-static behavior of the bond between GFRP (glass fibre reinforced polymer) rebars and concrete. The pull-out set-up with eccentrically GFRP bar was adopted to measure the effect of three parameters: (1) thickness of the concrete cover, (2) diameter and surface of the bar and (3) concrete mechanical properties. GFRP unidirectional E-glass rebars were considered of two diameters (6 and 8 mm) and two external surfaces (external ribbed surface cut into the bar after curing and surface deformed and coated with coarse sand). The rebars were embedded in cubic concrete specimens with three concrete covers: 10, 15 and 20 mm. Two concrete classes were used C25/30 and C50/60. The experimental results showed similar shear strength of GFRP and steel bars of diameter 8 mm, and an increasing shear strength increasing the concrete cover
Modelling bond of GFRP rebar and concrete
No full textThe structural performance of concrete structures reinforced using glass-fiber-reinforced-polymer (GFRP) rebars is sometime compromised by debonding failure. For better analyzing the GFRP bar-concrete bond behavior, this study presents two damage-based approaches for assessing the bond damage evolution. One is the secant modulus-based model and other is exponential damage model. Using the exponential damage approach, a simplified analytical model based on only one curve fitting parameter was developed to predict the bond stress-slip relationship. Then, a 3D finite element (FE) model was developed and both proposed damage-based approaches were implemented, to simulate the GFRP bond behavior. The FE model considers the nonlinear behavior of the concrete and the GFRP bar-concrete interface. The analytical and numerical predictions of the GFRP bar-concrete bond behavior are validated by comparing with the relevant results of an experimental program focused on quasi-static pullout tests. At the end, a parametric study was carried out to numerically assess the influence of some critical parameters on the bond behavior
Static and fatigue bond behaviour of GFRP bars and concrete
No full textThe experimental investigation is intended to study the influence of some parameters on the quasi-static and the
fatigue behaviour of the bond between glass fibre reinforced plastic (GFRP) rebars and concrete. This is an
important aspect in FRP reinforced concrete structural elements and of relevant importance in thin reinforced
concrete panels extensively adopted as façade or pavements. The pull-out set-up with eccentrically positioned
GFRP ComBAR® bar was adopted to measure the effect of two parameters on the bond mechanical features:
thickness of the concrete cover and concrete mechanical properties. For cycling tests, another parameter, the
maximum load in the cycle, was introduced to estimate the fatigue life under different load levels. Quasi-static
tests showed that concrete compressive strength influence on bond properties is much more pronounced than that
of the concrete cover. Cyclic tests at highest load level revealed that higher concrete quality attained longer fatigue
life
Experimental investigation of the static and fatigue bond behaviour of GFRP bars and concrete
No full textThe experimental investigation deals with the quasi-static and fatigue behavior of the bond between GFRP (glass fibre reinforced polymer) rebars and concrete. Eccentric pull-out test set-up was adopted to measure the effect of concrete cover and concrete mechanical properties. For cycling tests, the ratio R of the maximum load in the cycle to the static strength was also varied to estimate the fatigue re-sistance under different load levels. GFRP rebars were considered of diameter 8 mm. Specimens were cast with two different concrete classes and bars were positioned according to two concrete covers. Cyclic loading was performed with two load levels. Quasi-static results show similar shear strength for the different concrete covers and the shear strength increases with the concrete mechanical proper-ties. Cyclic tests provide a fatigue life exceeding one million cycles for the minimum load level con-sidered while for the maximum the number of cycles to failure extremely increase considering the higher concrete quality
Concrete cover effect on the bond of GFRP bar and concrete under static loading
Full text linkPaper presents assessment of bond behaviour between GFRP bars and concrete, investigated through set of centric and eccentric pull-out specimens. Main parameters under investigation are 1) bar external surface, 2) concrete mechanical properties and 3) concrete cover. Corresponding tests with steel reinforcement are performed for comparison in some cases. DIC technique was used for recording and evaluating of strain field on frontal side of eccentric specimens. Consequently, cracking patterns and local bond behaviour are described in details. Increasing of concrete mechanical properties always enhanced bond strength and delayed cracking of concrete cover. Ribbed GFRP bars showed excellent bonding performance when combined with low concrete cover. Their low splitting tendency and specific rib geometry developed better bond behaviour in case of eccentric tests, which showed the possibility of a proper prediction of the bonding behaviour of structural components
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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