Article

Strengthening of Steel-Concrete Composite Girders Using Carbon Fiber Reinforced Polymers Sheets

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Abstract

The use of advanced composite materials for rehabilitation of deteriorating infrastructure has been embraced worldwide. The conventional techniques for strengthening of substandard bridges are costly, time consuming, and labor intensive. Many new techniques have used the lightweight, high strength, and the corrosion resistance of fiber reinforced polymers (FRP) laminates for repair and retrofit applications. The load-carrying capacity of a steel-concrete composite girder can be improved significantly by epoxy bonding carbon fiber reinforced polymers (CFRP) laminates to its tension flange. This paper presents the results of a study on the behavior of steel-concrete composite girders strengthened with CFRP sheets under static loading. A total of three large-scale composite girders made of W355 X 13.6 A36 steel beam and 75-mm thick by 910-mm wide concrete slab were prepared and tested. The thickness of the CFRP sheet was constant and a different number of layers of 1, 3, and 5 were used in the specimens. The test results, showed that epoxy-bonded CFRP sheet increased the ultimate load-carrying capacity of steel-concrete composite girders and the behavior can be conservatively predicted by traditional methods.

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... The report by Tavakkolizadeh et al [4] presents their results on the behavior of steel-concrete composite girders retrofitted with CFRP sheets (a width of 3 in. and thickness of 0.05 in per sheet) under static loading. ...
...  "Initial Test": data set taken during "initial test" (Sept. 4,2002).  "t = 0 year" : data set taken during "shortly after installation test" (Aug. ...
... A simple analytical tool was developed based on strain compatibility relationship (see Equation 4.1 and Fig. 32) to predict the extreme fiber strain in the CFRP plate ( EXT ) from strains measured on the steel girders. These simple analytical predictions were compared with the strains measured during the post-installation load tests (t = 0 year and t = 1 year). ...
Technical Report
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Many state, county, and local agencies have deteriorating short to medium span bridges. These bridges are commonly single span or multiple span continuous structures, and are composed of rolled or welded longitudinal steel stringers used as part of a continuous slabon- girder bridge. Most of these bridges continue to serve as an integral part of the transportation system yet need some level of strengthening due to increases in live load demand or loss of section due to deterioration. The bridges are usually not critical enough to warrant replacement so a structurally efficient but cost- effective means of strengthening must be employed. In the past, the use of bolted steel cover plates was a common retrofit option for strengthening such bridges. This report documents the design, testing and implementation of a bridge strengthened by installing carbon fiber reinforced polymer (CFRP) plates to the bottom flange of girders in the positive moment region. The bridge is a three span continuous span steel structure located in Pottawattamie County with supplemental steel cover plates in the negative moment regions. Based on calculations completed by the bridge owner, it was determined that the positive moment regions of the interior girders in both the end and center spans of the selected bridge were overstressed. Design computations indicated that the overstressed girders could be adequately strengthened by the addition of CFRP plates bonded to the bottom flange of the girders. Based upon load tests and evaluation of the strengthened bridge response (immediately after strengthening and one year later), it was found that the overstressed bridge girders were adequately strengthened by the addition of CFRP plates. All CFRP plates installed on both exterior and interior girders were visually inspected approximately one and two years after their installation to observe any degradation or other changes that may have an influence on the integrity of the strengthening system. In general, no obvious debonding was observed and the condition of the CFRP plates seemed intact. Overall, the use of the CFRP plates appears to be a viable strengthening alternative for steel girder bridges.
... Many research studies have explored experimentally the e ects of strengthening or repairing steel beams and steelconcrete composite girders [3,[5][6][7] by adhesively bonding CFRP plates. For example, Fam et al. [3] used CFRP plates with elastic moduli varying from 200 to 400 GPa to strengthen three large-scale girders and repair 15 small-scale beams and reported 51 and 19% increase in flexural strength and stiffness, respectively, for the girders. ...
... In small beams with completely severed tension flanges, CFRP repair resulted in recovering up to 79% of strength before flange damage. Tavakkolizadeh and Saadatmanesh [5] and Al-Saidy et al. [6] also reported 44 to 76% increase in ultimate strength in composite girders strengthened with SM-CFRP and HM-CFRP plates. ...
... However, the tabular cohesive model functionality can be used to implement the damage variable (D) for the trilinear law. e damage variable of the trapezoidal law was derived by the authors using the values calculated from (5). ...
Article
Full-text available
Existing bond-slip (τ-s) relations for fibre-reinforced polymer (FRP)-steel joints employ different shapes and mathematical expressions, inferring that their predictions of failure load and mode, and other interface properties, might be inconsistent or inaccurate. In this study, predictions of four widely used τ-s relations are evaluated using a large experimental database of 78 double-lap FRP-steel specimens. To facilitate the evaluation process, a robust finite element (FE) model is developed for each test, implementing data from either of the existing τ-s relations to define the FRP-steel interface. Comparisons between test and FE results indicated that the existing τ-s models were unable of predicting the ultimate load (Pu) and effective bond length (Leff) of FRP-steel joints, or the relation between Pu and bond length and that between Leff and FRP modulus (Ef). A new τ-s model is developed based on an inverse FE simulation, comparison with experimental results, and regression analysis. It considers the effects of Ef, the type of FRP reinforcement (sheet or plate), and applies to both linear and nonlinear adhesives. The model predictions were validated by comparing with results from small bond tests and large FRP-strengthened steel beams tested under bending, yielding excellent results for Pu, failure mode, and all other interfacial properties.
... Many research studies have explored experimentally the e ects of strengthening or repairing steel beams and steelconcrete composite girders [3,[5][6][7] by adhesively bonding CFRP plates. For example, Fam et al. [3] used CFRP plates with elastic moduli varying from 200 to 400 GPa to strengthen three large-scale girders and repair 15 small-scale beams and reported 51 and 19% increase in flexural strength and stiffness, respectively, for the girders. ...
... In small beams with completely severed tension flanges, CFRP repair resulted in recovering up to 79% of strength before flange damage. Tavakkolizadeh and Saadatmanesh [5] and Al-Saidy et al. [6] also reported 44 to 76% increase in ultimate strength in composite girders strengthened with SM-CFRP and HM-CFRP plates. ...
... However, the tabular cohesive model functionality can be used to implement the damage variable (D) for the trilinear law. e damage variable of the trapezoidal law was derived by the authors using the values calculated from (5). ...
Article
Full-text available
Existing bond-slip (τ-s) relations for fibre-reinforced polymer (FRP)-steel joints employ different shapes and mathematical expressions, inferring that their predictions of failure load and mode, and other interface properties, might be inconsistent or inaccurate. In this study, predictions of four widely used τ-s relations are evaluated using a large experimental database of 78 double-lap FRP-steel specimens. To facilitate the evaluation process, a robust finite element (FE) model is developed for each test, implementing data from either of the existing τ-s relations to define the FRP-steel interface. Comparisons between test and FE results indicated that the existing τ-s models were unable of predicting the ultimate load (Pu) and effective bond length (Leff) of FRP-steel joints, or the relation between Pu and bond length and that between Leff and FRP modulus (Ef). A new τ-s model is developed based on an inverse FE simulation, comparison with experimental results, and regression analysis. It considers the effects of Ef, the type of FRP reinforcement (sheet or plate), and applies to both linear and nonlinear adhesives. The model predictions were validated by comparing with results from small bond tests and large FRP-strengthened steel beams tested under bending, yielding excellent results for Pu, failure mode, and all other interfacial properties.
... Carbon fiber-reinforced polymer (CFRP) strengthening systems have significant potential for retrofitting metallic structures, particularly railway and roadway bridges [4][5][6][7]. The strengthening of steel structures using externally bonded (EB) CFRP laminates has many advantages, such as a high strength-to-weight ratio, resistance to cor-rosion, ease of installation in the inconvenient construction sites, rapid installation with minimum disturbance to traffic, and lower sensitivity to cyclic loading, in comparison with existing conventional strengthening methods [4,5,[8][9][10][11][12][13][14]. EB CFRP laminates have been successfully used for flexural strengthening of steel beams [14][15][16][17][18][19], strengthening against local and global instability [20][21][22][23][24][25][26], and strengthening against cyclic loading [6,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. ...
... The strengthening of steel structures using externally bonded (EB) CFRP laminates has many advantages, such as a high strength-to-weight ratio, resistance to cor-rosion, ease of installation in the inconvenient construction sites, rapid installation with minimum disturbance to traffic, and lower sensitivity to cyclic loading, in comparison with existing conventional strengthening methods [4,5,[8][9][10][11][12][13][14]. EB CFRP laminates have been successfully used for flexural strengthening of steel beams [14][15][16][17][18][19], strengthening against local and global instability [20][21][22][23][24][25][26], and strengthening against cyclic loading [6,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Additionally, studies have demonstrated the effectiveness of EB CFRP systems for the retrofitting of old metallic bridges [43][44][45][46]. ...
... By dividing the CFRP laminate segment from the far end to the crack edge into n segments, as shown in Fig. 13(b), approximate solutions for Eqs. (13) and (14) can obtained: By substituting Eqs. (8) in to (13), the following can be obtained: ...
Article
Full-text available
The strengthening of steel structures using externally bonded (EB) carbon fiber-reinforced polymer (CFRP) laminates has gained popularity due to the advantages such as their high strength-to-weight ratio and corrosion resistance. Even though previous studies showed the application of EB CFRP laminates can enhance the fatigue performance of cracked steel plates, little is known regarding the high-cycle fatigue performance of CFRP-to-steel bonded joints. As debonding of the CFRP laminate from the steel substrate is a commonly observed failure mode under fatigue loading, a sound understanding of the behavior of CFRP-to-steel bonded joints is crucial for a better understanding of the behavior of CFRP-strengthened cracked steel plates under fatigue loading. This study experimentally and theoretically investigates the fatigue performance of CFRP-strengthened cracked steel plates. Five pre-cracked steel plates were strengthened with CFRP laminates and tested under fatigue loading. The test results for the failure modes, the fatigue-life extension, and the behavior of the CFRP-to-steel bonded joint were discussed. A numerical modeling approach based on a recently developed bond-slip model for the behavior of the CFRP-to-steel bonded interface under fatigue loading is presented for modeling the behavior of the CFRP-strengthened cracked steel plate. Although the proposed theoretical model is conservative, this method accurately predicted the remaining fatigue life of CFRP-strengthened cracked steel plates.
... A espessura da folha de PRFC foi mantida constante e os corpos de prova tinham 1, 3 ou 5 camadas. Os resultados dos testes mostraram que a chapa de PRFC colada com epóxi aumentou a capacidade de carga final das vigas mistas de aço-concreto, e que o comportamento pode ser previsto de forma conservadora usando métodos tradicionais (Tavakkolizadeh;Saadatmanesh, 2003). ...
... A espessura da folha de PRFC foi mantida constante e os corpos de prova tinham 1, 3 ou 5 camadas. Os resultados dos testes mostraram que a chapa de PRFC colada com epóxi aumentou a capacidade de carga final das vigas mistas de aço-concreto, e que o comportamento pode ser previsto de forma conservadora usando métodos tradicionais (Tavakkolizadeh;Saadatmanesh, 2003). ...
Conference Paper
Full-text available
Os materiais compósitos possuem grande importância quanto à aplicação estrutural, combinando grande resistência mecânica e baixa massa específica; tais características são de grande valia para o retrofit. Nesse sentido, este trabalho tem como objetivo - por meio de uma RSL - o estudo da viabilidade da utilização da fibra de carbono na recuperação de estruturas. Os resultados são muito promissores, sendo que o uso desta técnica proporcionou um desempenho superior comparado às estruturas não reforçadas.
... Research has now established the effectiveness of strengthening of metallic beams by bonding CFRP plates. Mertz and Gillespie [49], Sen et al. [50], Moy and Nikoukar [51], Tavakkolizadeh and Saadatmanesh [52], and Nikoukar [53] confirmed the improvement of strength and stiffness of metallic beams with bonded CFRP plates. ...
... In another study conducted by Tavakkolizadeh and Saadatmanesh [52], a total of three large scale composite girders made of steel beams and a concrete slab were bonded with one, three and five layers of 1.27 mm thick CFRP sheet, with a Young's modulus of 144 GPa. The overall lengthens of the sheets were identical but the cut-off points for each layer were staggered to prevent premature failure at termination point due to stress concentration. ...
Thesis
p>Since the 1990s, the use of carbon fibre reinforced polymer (CFRP) materials has made large advances in the civil engineering construction field, particularly in the bridge upgrade and rehabilitation. To date, there are many applications in metallic beams strengthened with a bonded CFRP plate. However, the design method and technique are not sophisticated, and some specific areas require further research. In this technique, the structural adhesive bonding is the most distinct element to be considered. The main aspects discussed in this thesis are interfacial stress analysis, the behaviour under static loading and the fatigue performance. Firstly, an analytical solution and a numerical procedure are presented to calculate the stresses in beams reinforced by CFRP plates with a uniform thickness as well as with ends that are tapered. Finite element analysis was employed to validate the analytical results and a parametric study was carried. Secondly, ten retrofitted steel beams were tested under static loading to investigate the factors influencing the strength, such as different length and thickness of CFRP plates, the effects of the end taper and of the adhesive spew fillets beyond the plate ends. The test results were also used to validate the results of the analytical stress analysis. Thirdly, nine further retrofitted steel beams were tested under fatigue loading. Backface-strain technique was applied to monitor crack initiation and growth, and to assess the effect of the spew fillets. An S-N curve based on the peak interfacial stresses is proposed to predict the fatigue performance of the retrofitted beams. Finally, Finite element analysis was employed to investigate the geometric effect of the spew fillet and of the taper at the plate end of the retrofitted beam. The results confirm that the spew fillet size has a large effect on the strain in the plate ends. In the conclusion, a simple and integrated design method/technique for steel beams reinforced by bonded CFRP plates is proposed, based on the findings obtained from the studies presented.</p
... Extensive experimental tests and numerical analyses are conducted to explore the potentiality of CFRP strengthened RC members subjected to static loadings. [1][2][3][4][5][6][7] Nevertheless, research is very limited on the behavior of CFRP strengthened RC members under dynamic loadings such as transverse impact loading. [8][9][10][11][12] Furthermore, a few studies, which have been conducted on RC members wrapped by CFRP layers under unequal lateral impact loading, are limited in scope, and their conclusions are preliminary as they are among the first on this topic. ...
... where, f cs , f cd are the static and dynamic compressive strength at a strain rate _ ε d , _ ε s ¼ 30 Â 10 À6 s À1 (static strain rate), respectively. logγ ¼ 6:156α À 0:49, α ¼ 5 þ 3 f cu= 4 ð Þ À1 and f cu is the static compressive strength (in MPa). 43 The TDIF for concrete in tensile response is defined by Malvar and Ross, 50 as follow in Equation (20): ...
Article
With the plethora of data on how CFRP layers enhance RCs under static loads, research on how the reinforced structural components react to unequal lateral impact loads from a derailed train striking metro station columns or a car accident is lacking. A similar motivation inspired the current study, which sought to create a numerical technique backed by actual testing to evaluate RC members with CFRP in a range of unequal lateral impact scenarios. This paper uses explicit nonlinear finite element techniques to numerically analyze the response of unequal lateral impact‐loaded RC members wrapped in (CFRP) layers. Diverse variables related to CFRP, concrete, steel reinforcement, and impact energy are investigated. This kind of thorough analysis provides unique insights to strengthen RC members against unequal lateral impact loads. The effects of internal forces and deflections, as well as absorbed energy on the impact response of CFRP‐RC components, were investigated and verified by prior experimental results. A parametric sensitivity analysis was conducted after the strain characteristics of steel bars confirmed the finite element model, reinforcement ratio, impact velocity, CFRP properties, and ductility index all influence the member's impact response. This study's results will help advance the field's understanding of CFRP‐RC components analysis and design under unequal lateral impact.
... The use of bonded steel plates and bars for the strengthening and rehabilitation of RC structures has been popular for years [45,46]. Recently, several new techniques have used the light weight, high strength, corrosion resistant FRP laminates for repairing and retrofitting applications [47][48][49]. The use of EB FRP laminates has been one of the most attractive methods for strengthening RC structures and a large number of research and practical projects have been undertaken [45,50]. ...
... 48 Load-deflection curves of the strengthened beams in series B before and after sustained loading and after ageing.On the effect of the previous sustained loading, group B2 beams showed, after yielding, flexural behavior similar or near to the flexural behavior of their corresponding aged beams in group B3, regardless their load carrying capacities and their ultimate deflections. ...
... The last two decades witnessed a great amount of research in the field of FRP strengthening of metallic structures [2,3]. The FRP composites have been successfully employed for 1) repair of damaged metallic airframe components to restore their original design strength by employing bonded composite patches or reinforcements [4][5][6]; 2) flexural strengthening of metallic beams by adhesive bonding of FRP laminates on the soffit side of beams [7][8][9]; 3) enhancing the stability of slender metallic structural components subjected inelastic local buckling near joints [10][11][12][13][14][15][16]; and 4) strengthening of thin-walled metallic sections subjected to shell buckling modes [17][18][19]. Haedir and Zhao [17] experimentally studied the carbon FRP (CFRP) strengthening of circular steel tubular short columns with a radiusto-thickness (r=t) ratio of 19-39, undergoing plastic buckling when subjected to axial compression. ...
... In this paper, the FRP strengthening of shells undergoing all possible shell buckling modes and buckling characteristics is numerically studied. The changes in buckling modes and buckling characteristics Nomenclature a half wavelength of sine form of axisymmetric outward imperfection; A cross-sectional area of the metallic shell; An aluminium shell of type n where n = 1, 2, 3, 4 and 5 and represent the metallic shell thicknesses of 1, 2, 3, 0.3, and 7.5 mm respectively; An-F0 bare aluminium shell of type n, without any FRP strengthening; An-F1-E l -E h instance of FRP strengthening of aluminium shell of type n, with 1 layer of FRP wrap of 0.17 mm thickness, whose modulus along the longitudinal direction E l and modulus along hoop direction E h are given; n = 1, 2, 3, 4 or 5; A4-F1 0 -E l -E h instance of FRP strengthening of aluminium shell of type 4, with 1 layer of FRP wrap of 0.05 mm thickness, whose modulus along the longitudinal direction E l and modulus along hoop direction E h are given; A 11 ,A 22 diagonal terms in extensional stiffness matrix defined in classical lamination theory [8]; B1 point of axi-symmetric buckling initiation; B2 point of asymmetric buckle initiation; d mean diameter of the metallic shell (mm); E Young's modulus of metallic shell material (GPa); E l longitudinal modulus of FRP wrap (GPa); E h hoop modulus of FRP wrap (GPa); E le (or)E 1e effective longitudinal modulus of FRP strengthened metallic shell (GPa); E he (or)E 2e effective hoop modulus of FRP strengthened metallic shell (GPa); h total thickness of FRP strengthened metallic shell (mm); K 1 pre-yield stiffness (kN/mm); K 2 pre-strain localization stiffness (kN/mm); K 3 post-strain localization stiffness (kN/mm); K 4 post-asymmetric buckle initiation stiffness (kN/mm); L length of the cylindrical shell (mm); P load along the axial direction of the shell (kN); P u ultimate buckling load (kN); r radius of the shell (mm); SL point of strain localization; ST-F0 bare steel tube without any FRP strengthening; ST-Fn steel tube with n number of layers of GFRP unidirectional wrap in the circumferential direction; n = 1 or 2; ...
Article
Buckling performance of thin metallic shells can be enhanced by external wrapping of FRP composite layers. But the effectiveness and the extent of such FRP strengthening is influenced by the buckling characteristics of the metallic shell. This paper presents a detailed numerical study to bring out the changes in buckling behaviour and buckling modes of metallic cylindrical shells of different r/t ratios, exhibiting all varieties of buckling viz. elastic, axisymmetric plastic, and asymmetric plastic, due to changes in the hoop and longitudinal stiffness of the FRP wrap. The most general buckling behaviour of the FRP strengthened shells exhibiting elastic, pre-strain localization, post strain localization, axisymmetric buckle growth, and the asymmetric buckle growth stages are being brought out. Subsequently, the influence of parameters viz. r/t ratio, modulus and yield strength of the metallic shell, and the type and magnitude of the FRP strengthening on this general buckling behaviour are analysed. The results demonstrate that 1) the elastic buckling shells display a stepwise increase in load capacity with an increase in hoop modulus of the FRP wrap; 2) for the plastic buckling shells undergoing asymmetric buckling modes, a minimal increase in longitudinal stiffness of FRP wrap, just sufficient to reach the shells’ yield capacity, would lead to an optimal design; and 3) for the plastic buckling shells failing due to axi-symmetric bulging at their ends, the increase in longitudinal stiffness of FRP, increases both the yield capacity and the pre-strain localization stiffness, leading to a large increase in buckling capacity.
... In 1991, Urs Meier and his colleagues made a significant contribution to the field of civil engineering by using CFRPs in their lamellar form to renovate the Ibach Bridge in Lucerne [8]. This pioneering work opened the way for other infrastructure consolidation projects using this technique [9,10]. The CFRP lamellar materials developed by EMPA are now widely used to consolidate or rehabilitate buildings, bridges, or structural elements that require various interventions in Europe. ...
Article
This paper presents the results of the Finite Element Analysis using SolidWorks simulation of the strengthening effect of the CFRP wraps applied to the bottom of concrete pillars bearing uniaxial compression forces. The benefits of using CFRP wrap have been emphasized by analyzing the resulting values of Displacement, Strain, and Factor of Safety.
... Li et al. (2014) examined the tensile behaviour of steel plates connected with BFRP. Both the postyield modulus and ultimate bearing capacity of basalt steel composite rose approximately linearly with the number of outside BFRP layers from 0 to 8. In contrast, Tavakkolizadeh and Saadatmanesh (2003) discovered that the average failure stress of CFRP declined from 75% of the ultimate tensile strength to 42% as the number of CFRP layers increased from 1 to 5, resulting in a reduction in the strengthening effectiveness of the beams. Shenghu Cao et al. (2009) examined CFRP and hybrid FRP tensile qualities at extreme temperatures. ...
... Previous work in this area of building house units using recycled plastics include efforts by Tavakkolizadeh and Saadatmanesh (2003), the work of Cho, et al (2012) who studied response of the composite materials to loads and Chaallal and Shahawy (2000) who developed a patented solution to plastics problem through buildings. These research efforts contributed to efforts to recycle and need for affordable buildings and to conserve environment. ...
Article
Full-text available
Disposal of plastic wastes is a major global problem. One of the best solutions to the problem of disposal of plastic wastes is through recycling to produce other usable composite materials leading to improved environmental sustainability. It is important for developing nations to build capacity for plastic waste management to ensure clean environment. One of the areas for capacity building is in the construction industry. The industry is a major consumer of costly cement, sand and aggregate whose costs can be reduced by use of recycled plastics processed through melting and re-moulding into desired blocks and structural building materials. The main goal of this research is to help in attaining sustainability in development through recycling of plastic wastes for affordable housing. Research objectives were to design a low cost house made of recycled plastics and composite materials for building; to analyze mechanical behaviour of the building using finite element analysis in Simulia Abaqus and to propose measures to scale up production. Loading was by concentrated loads on truss and pressure on the roof and wall surfaces. Wind effects on the house were studied in Solid works flow simulation module. Results show that high strength fibre glass structures and the roofing sheet materials experienced high stresses. Stresses on recycled plastic blocks on walls were low.
... Other similar investigations of the use of CFRP strips attached to the tension flange of I-girders have demonstrated generally improved flexural capacityproportional to the CFRP appliedalthough little improvement to girder stiffness (Sen et al. 2000;Tavakkolizadeh and Saadatmanesh 2003a;Lenwari et al. 2005). In such applications, Lenwari et al. (2006) demonstrated that the stress intensity at the ends of CFRP plates governs the debonding strength and that this region is critical for the initiation of debonding. ...
Technical Report
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This project investigated practical repair methods using high performance and traditional materials which can be applied to corroded and/or damaged steel girder ends in their in-situ state. Observed corrosion damage follows well known patterns: beam end corrosion is associated with leaking expansion joints and is most prevalent at bottom flange-to-web interfaces where debris accumulates, trapping moisture. The current state of practice for structural repair of beam ends is the complete replacement of the affected region. For localized damage, bolted or welded steel patches and/or doubler plates are used. An experimental study involving static tests of corrosion-damaged beam ends to failure is reported. End A tests were conducted without conditioning and End B tests were conducted following one million cycles of fatigue conditioning. Two control (undamaged Girder 1A and corrosion damaged Girder 2A) and four repair techniques (Girders 3-6) were tested: conventional bolted steel repair; ultra-high performance concrete (UHPC) encasement; normal strength reinforced concrete (RC) encasement; and adhesively bonded glass fiber reinforced polymer (GFRP) plates, respectively. All methods but GFRP performed well, restoring the undamaged strength and stiffness of the steel girder regardless of fatigue conditioning. GFRP repairs were unsuccessful. An extensive finite element modeling campaign was conducted and validated based on the experimental program. The modeling of the test specimens proved to be robust and captured observed behavior well. Recommendation for appropriate means of repairing corrosion damaged beam ends are provided.
... CFRP tapes are used intensively for reinforcement of the concrete structures [8] and an application of them in wooden structures [9] is possible as well. Among different constructions, there are specific examples of strengthening with CFRP tapes, which were introduced in the following works: the roof structure of a historical church by Huster et al. [10], masonry walls by Bastianini et al. [11], and bridges in Poland [12], the UK [13,14], and the United States [15]. This paper aims to study the constructions reinforced with CFRP tapes in order to find the best solution and point to the trouble spots in them. ...
Article
Full-text available
Carbon fiber reinforced polymer (CFRP) composites are increasingly being used to strengthen structures and to retrofit existing structures. CFRP composites are used in various industries: construction, automotive, and many others. This literature review has shown that CFRP composites find numerous practical applications. Improving structures by reinforcing them with CFRP composite is an innovative approach in design. This review aims to explore the current state of the art in the types of structures that can be reinforced with CFRP, and modifications to the CFRP composite as an additional aspect to increase the strength of the reinforced structure. It has been shown that regardless of the type of reinforced material, the most critical element in this connection is the bonded joint. Proper surface preparation and the use of an appropriate adhesive are also important.
... Fibre-reinforced polymers (FRPs) have emerged as a viable solution for enhancing the ultimate capacity of steel and RC structures in recent decades [1][2][3][4][5][6][7]. The benefits of employing FRPs, especially Carbon Fibre-Reinforced Polymers (CFRP), as stiffening members are widely established in the construction steel industry [8][9][10][11][12][13]. CFRP, due to its superior tensile modulus, chemical resistivity, lightweight and resistance to corrosive degradation, has been used in strengthening steel over the recent years [9,[14][15][16][17][18]. Colombi and Poggi strengthened steel beams with pultruded CFRP strips as shown in Fig. 1 and observed an increase in strength by up to 23%. ...
Article
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Cold-formed steel (CFS) members may need strengthening for a multitude of reasons such as their intrinsic weakness to fail locally before the design load is reached, deterioration due to corrosion or modification in the design standards. Fibre-reinforced polymers such as glass-fiber-reinforced polymers (GFRP) have been increasingly used for strengthening deficient steel structures. GFRP is usually employed as wet-laid laminates or as pultruded plates. The present work is a laboratory and finite element study for comparing the effectiveness of GFRP wet-laid laminates and pultruded plates as reinforcement elements for thin CFS members. A total of 10 specimens were tested in laboratory under tension. Two different reinforcement lengths (i.e., along the entire steel member and other being a central reinforcement patch) were studied for steel members strengthened with fabric laminates and pultruded plates. It was observed that CFS members reinforced with GFRP plates and GFRP laminates exhibited different failure modes. While the dominant mode of failure in the wet-laid laminates was debonding, steel yielding was observed in specimens reinforced with pultruded plates. Also, a 34% increase in the strength was observed in the specimens where pultruded plates were used and about 16.85% in the specimens where laminates were used for strengthening. This indicates that GFRP pultruded plates performed better in reinforcing thin CFS members. It was also found that reinforcing the entire length of the steel member could increase the effectiveness of the strengthening technique significantly. A finite element model was simulated and validated against the experimental results. The validated finite element model was then employed to study the effect of key parameters affecting the economy of the strengthening technique. It was observed that the thickness of GFRP can be optimized, and for the present study, a GFRP thickness of 6 mm was found to be optimum.
... Compared with traditional building materials such as steel, reinforcing bar, and concrete, carbon-fiber-reinforced polymers (CFRPs) have excellent properties of lightweight, high strength, and corrosion and fatigue resistance, and they has been widely used in the construction and reinforcement of engineering structures. Studies showed that reinforced concrete structures (Hawileh et al., 2013;Hawileh et al., 2014), steel beam structures (Teng et al., 2015;Ghafoori et al., 2015), and steelconcrete composite structures (Tavakkolizadeh and Saadatmanesh, 2003;Karam et al., 2017) can be effectively improved in terms of flexural bearing capacity, fatigue life, and cracking performance after strengthening with CFRP laminates. ...
Article
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This work studies the improvement in the inelastic mechanical property of steel-concrete composite beams strengthened by carbon-fiber-reinforced polymer (CFRP) laminates under a negative moment. First, the monotonic loading test was designed and performed on an inverted simply supported beam to simulate the negative moment regions of continuous composite beams. Second, the finite element analysis (FEA) on flexural capacity and cracking resistance in negative moment regions of the composite beams was carried out with ANSYS software. A series of mechanical indexes including the load-deflection curve, component strain, and crack propagation were obtained from the FEA model and verified through the test data. The results showed that the FEA model can accurately predict the general mechanical behavior of composite beams under negative moments, and the calculation results considering the interface slip effect were closer to the experimental values. Finally, based on the FEA model, the parametric study on static behavior in negative moment regions of composite beams strengthened with/without CFRP laminates was conducted. The effects of the CFRP layout width, layout position, layer number, longitudinal reinforcement ratio, and shear connection degree on the bearing capacity of the composite beams were considered. The CFRP laminates can effectively improve the bending resistance of composite beams under negative moments. At a low reinforcement ratio, the bearing capacity was greatly affected by the layout width and layer number of the CFRP laminates, but the rate of increase was not significant when the layer number was more than 3. The reinforcement ratio had a great influence on the bearing capacity of composite beams under negative moments, but the influence of the shear connection degree was not remarkable.
... The one-layer CFRP has provided sufficient lateral bearing capacity to maintain the specimen in an overall flexed state. At this time, the resistance of the member is controlled by its bending strength, and the excessive number of layers does not provide greater rigidity to the member [14][15] [16]. ...
Conference Paper
In recent years, fiber-reinforced polymer (FRP) use to enhance existing structural members’ impact resistance has become a research hotspot. This paper investigates Carbon Fiber Reinforced Polymer (CFRP) effectiveness to increase Impact Resistance of Reinforced Concrete Square Member under lateral impact loads. This article clearly said that increased strength of concrete members using CFRP layers leads to increased CFRP layers’ strain. To investigate the effectiveness of Carbon Fiber Reinforced Polymer's use to increase the impact resistance of reinforced concrete square members under lateral impact loads is studied; falling-weight impact tests were conducted. The impact load was applied to the 2L/9 from the length of the RC member's span with a free-falling hammer. All of the specimens with both ends fixed support with short span members were used for these experiments. In this study, the strengthening method and material properties of the CFRP layers and the number of CFRP layers were varied. The results show that using CFRP to strengthen the square RC member specimen in shear effectively prevents shear failure and leads the specimen’s response to be flexural dominated. The short span of the square RC member turns to be shear failure mode dominated by diagonal cracks. The square RC member strengthens with CFRP is shown as bending failure with vertical cracks longitudinal bars rupture. Compared with the square RC member, the impact peak value of the CFRPRC members changes little.
... Anyway, for steel beams, the main problem is in the form of de-bonding at the end of the FRP laminates. This is usually due to large strain and stress amount occurred at the end of the FRP laminates [14,[19][20][21], therefore end bolting anchorage plates technique was used. Several investigators have verified some solutions to overcome this shortcoming (i.e. ...
Article
Three steel beams were made-up and tested to study the effect of CFRP (Carbon Fiber Reinforced Polymer) laminates with and without end anchorage plates on the behavior of flexural strength of steel beams. Tested steel specimens are equal in clear span length, gross sectional area, and strengthened by intermediate stiffeners. Three types of specimens were made, the first specimen was considered as a reference one, while the other two were reinforced by CFRP laminates with and without end anchorage plates respectively. From the experimental outcomes, it was found that, the load deflection curve and load strain responses for specimens strengthened by CFRP strips became stiffer in comparison with the reference beam. On the other hand, it was found that, the deflection values for strengthened beams by CFRP without and with end anchorage plates were decreased to 58.33% and 79.95%, while, the strain values were decreased to 63% and 85.55% respectively, in comparison with the reference beam at yielding stage at load (Py = 20 kN) while, at failure stage at load (Pu = 45 kN) for reference beam, the deflection values for strengthened beams by CFRP without and with end anchorage plates were decreased to 81.19% and 88.13%, while, the strain values were decreased to 88.6% and 97.14% respectively, in comparison with the reference beam. Also, the percentages of increasing in yielding -load for strengthened beams by CFRP without and with end anchorage plates were increased to 100 % to 225 %, while, the percentages of increasing in ultimate-load for strengthened beams by CFRP without and with end anchorage plates were increased to 38.88 % to 111.11 %, respectively, in comparison with the reference. Finale the failure mode for reference beam was flexural failure type (plastic hinge), while, the failure mode for strengthened beams by CFRP without and with end anchorage plates was sudden; because of the de-bonding at the end of the CFRP strips and at the end of carbon fibre that due to the stress concentration at the ends of the CFRP.
... For example, carbon fiber-reinforced polymer (CFRP) laminates can be applied in retrofitting of steel structures instead of conventional mechanical fasteners due to their light weight and low-cost advantages. Recent studies have shown that the use of CFRP offers an excellent alternative method for repairing deteriorated structures [1][2][3][4][5][6][7]. The main application of CFRP laminates is to make structures lighter while maintaining their integrity and strength [8]. ...
Article
Full-text available
Carbon fiber-reinforced polymer (CFRP) materials have been effectively used as externally bonded sheets to repair damaged steel structures such as airplanes and ships. In this study, a series of double strap joints with different bonding lengths are considered and examined to experimentally and theoretically assess the effective bond length. Various models exist in the literature which are used to predict the strength of steel and CFRP joints under various loading conditions. Non-linear Lagrange stress method (NLS) which is a novel stress-based method for predicting the failure load values is presented for the first time. This approach is based on 2D and 3D linear elastic finite element analysis. Relying only on two experimental tests, the new approach proposed here can quickly and easily predict the failure load in steel/CFRP samples. In this methodology, it is assumed that the adhesive joint will fail as the normal stress along the adhesive mid-line reaches a predetermined value at a critical distance. In addition, experimental data on steel/CFRP joints gathered from the literature are compared to predictions using the NLS method. It was found that results from the theoretical predictions (NLS) were in good agreement with experimental tests conducted on double strap joints. It was also revealed that the average accuracy of the NLS method is superior to other methods such as cohesive zone model and Hart-Smith. The results revealed that under the best conditions, the NLS model is 5 times more accurate than existing models.
... Using a single layer of 5.25 mm thick CFRP sheet, a stiffness increase of 11.6% was measured from field tests. Similar studies were conducted by Tavakkolizadeh and Saadatmanesh [19] on 4.8 m effective span steel-concrete composite girders externally bonded with pultruded CFRP composite sheets and a 76% increase in load-carrying capacity was observed with concrete compression crushing being the failure mode. Similar retrofitting technique was also studied on damaged steel-concrete composite specimens by Al-saidy et al. [1] which showed that testspecimens gained 23% more than the strength of the undamaged control specimen with a similar failure mode of concrete compression. ...
Article
Full-text available
Experimental and numerical study on the flexural strengthening of rolled steel beams using intermediate modulus pultruded Carbon Fibre Reinforced Polymer (CFRP) composite sheets is presented in this paper. De-bonding is the commonly observed failure mode in external strengthening of steel structural elements using CFRP composite sheets. One control and seven strengthened steel beams bonded with CFRP composite sheets along with different anchorage systems such as mechanical fasteners and intermittent carbon fibre fabric composite wraps were tested up to failure. The influence of anchorage systems on load/deflection behaviour, load-carrying capacity, toughness, stiffness, failure strain, failure mode, and deflection ductility of strengthened beams were found from the test data. Finite element (FE) models of the specimens generated using FEA software ABAQUS were analysed and compared with experimental data. The test results show that steel beams with external bonding along with intermittent U-wraps have better performance in terms of load-carrying capacity, toughness, and deflection ductility. The increase in load carrying capacity was up to 19% and the maximum strain in CFRP sheet reached up to 69% of its rupture strain. Parametric studies were also conducted for strengthening steel girders to find the effect of dimensions and orientation of CFRP composites used in the strengthening schemes.
... Using the equivalent strain energy density based on the failure criterion a bond failure model was proposed. Tavakkolizadeh and Saadatmanesh [18,19] and Photiou et al. [20] studied the behavior of damaged steel-concrete composite steel girders repaired with CFRP sheets under static loading. Three scenarios of 25%, 50%, and 100% loss of tension flange area of the W-shape cross-section were investigated. ...
Article
Full-text available
This study addresses the feasibility of reusing pre-damaged steel beams in temporary structures. The extensive structural investigation of notch-damaged, unrepaired, and laterally unsupported steel beams was performed experimentally and numerically. The simply supported specimens were tested in two-point loading with the study parameters being the location and size of the notch. Some beams had one notch on one edge of the tension flange at different locations, and some beams had two notches on both edges of the tension flange. Three-dimensional numerical models were generated to simulate the behavior of the test beams. After verifying the model, the numerical analysis was extended to cover additional different notch depths and widths. The study showed that the capacity of beams with single notch was more influenced by the notch depth increase than it was by the increase in the notch width. Beams with double notches exhibited an even more pronounced and distinct decrease in the capacity as the notch depth and width increased. This investigation supports the feasibility of reusing pre-damaged steel beams in temporary structures under service loads and certain levels of damage, where the behavior of such beams is within the elastic range and the beam maximum defection is less than the allowable one.
... The effects of multi-layered CFRP strengthening was examined by Tavakkolizadeh and Saadatmanesh [134] on several steel-concrete girders. The 4.78 m girders were patched with one, three or five layers of low modulus (144 GPa) CFRP sheeting on the external surface of their lower flange. ...
Article
Full-text available
This literature review has examined the use of FRP composite materials as a potential retrofitting technique for civil structures. Importantly, the various material properties, bond mechanisms , durability issues and fatigue resistance have been discussed. Studies exploring the performance of CFRP repaired steel have strongly indicated its potential as a rehabilitation material. These systems offer many improvements over the current bulky and less chemically resistant methods of bolting or welding steel plate patches. This review has established and highlighted the factors that affect CFRP/steel bond durability, namely surface preparation, curing, corrosion, fatigue loading, temperature and moisture ingress through studies that focus on their effect. These studies, however, often focus on a single influencing factor or design criteria. Only limited studies have investigated multiple parameters applied simultaneously, even though they commonly occur together in industrial practice. This review aimed to summarise the numerous influencing parameters to give a clearer understanding of the relevance of CFRP repaired steel structures.
... 5,9,10 Several experimental studies have been conducted to study the effect of CFRP patches on fatigue crack propagation. [11][12][13] Several studies have also been conducted to address the phenomenon of bending of hollow steel beams, reinforcing them with CFRP patches. Shaat and Fam 14 performed experimental tests by reinforcing short and long hollow rectangular beams in various ways and they concluded that the maximum load before buckling increased by 18% in short beams and 13% to 23% in long beams. ...
Article
Full-text available
The use of composite materials patches for the reinforcement of steel structures attracts particular interest. Due to their high strength, light weight, and high fatigue and corrosion resistance, composite patches represent a versatile reinforcement solution. In this paper, the reinforcement of steel beams with CFRP patches is examined. Large scale tests of “H” and “square hollow” cross section steel beams are conducted. The beams are reinforced with CFRP patches, investigating the effect of the thickness and the length of the patch, and the type of the cohesive joint. All reinforced specimens showed increase of their stiffness and their maximum load capacity. Furthermore, advanced finite element models are developed for the simulation of the mechanical behavior of the reinforced steel beams. FE results relate very well to the experimental ones for most of the measured magnitudes, thus verifying the reliability of the developed models in estimating stiffness, yield load and maximum load capacity of the beams.
... FRP has been widely used in strengthening concrete structures, and extensive research has already been conducted (e.g. [50,30,29,35,38,33]). Recent experience in the USA [48,49,26,20,36,6,27], the UK [17,31,5,24] Japan [46] and Switzerland [4] showed that there is a great potential for CFRP to be used in the retrofitting of steel structures. However, many issues need to be resolved before this advanced material can be fully utilised to provide confident retrofitting of existing structures. ...
... The improvement in ultimate strength of the adjusted steel girders conforming with various strengthening ratios of CFRP are illustrated in Fig. (3) [40,41,42]. This Figure reveals that the influence of using CFRP on improving the ultimate strength is obvious for small values of yield strength. ...
Article
Full-text available
Abstract: In latest years, the application of carbon fiber reinforced polymer (CFRP) composites for strengthening structural elements has become one of the efficient options to meet repair due to fatigue cracking, corrosion or the increasing cyclic loads. Therefore, the aim of this survey is to explore the existing carbon fiber reinforcing polymer (CFRP) techniques used for strengthening structural steel elements that are damaged due to fatigue. The current survey also deals with the researches that studied the efficiency of using (CFRP) in strengthening steel beams and rehabilitating (reestablishing) damaged ones. It also reviews the researches that used the finite element method (FEM) to evaluate the performance of steel beams strengthened by CFRP
Thesis
La corrosion est une réaction chimique entre un matériau, généralement un métal, et son climat, entrainant des dégradations du matériau et de ses propriétés. En fonction du type de métal, la corrosion peut provoquer une simple altération ou la destruction complète de ce matériau. Ainsi, pour des métaux comme le zinc ou le cuivre, la corrosion demeure superficielle. En revanche, pour un métal comme le fer, le phénomène de corrosion se traduit par une formation de rouille et se poursuit parfois jusqu’à destruction totale du métal. L’expérience montre, que la réparation traditionnelle des structures métalliques affectées par cette corrosion, sont souvent coûteuses et complexes, nécessitant, souvent le démontage des éléments de cette structure ou sa totalité, ce qui peut provoquer des perturbations importantes (cas des structures de ponts). Notre objectif, dans ce mémoire, est de contribuer à la compréhension des composites de carbone (CFRP) et leur effet lors de leur application, pour la réparation de ces structures. Il s’est avéré que ces composites, sont des techniques très efficaces et économiques (réduction du cout de réhabilitation) pour la mise à niveau des structures métalliques endommagées par la corrosion. Leurs avantages, tels : la rapidité d’exécution, la simplicité de mise en œuvre, l’augmentation de la rigidité de la structure réparée, l’excellente résistance mécanique et la bonne résistance à la corrosion, sont les arguments de notre choix. Une modélisation numérique, en faisant des analyses modales, basée sur la méthode des éléments finis (MEF), avec l’utilisation du logiciel ‘’Robot’’, pour un cas d’étude réel de pont corrodé, en prenant différents cas de renforcement par composites, feront l’objet de notre travail de mémoire. Une confrontation ‘’technico-numérique’’, des résultats obtenus, achèvera le contenu de notre manuscrit. Mots Clés : Corrosion, métallique, pont, PRS, composite CFRP, modélisation, Robot, analyses modale.
Thesis
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Steel structures are very popular in civil infrastructure as steel possesses good strength and ductility. They are extensively used in high seismic risk regions and in offshore structures across the world. However, the vulnerable effects of cyclic loading during earthquakes and winds on both onshore and offshore steel structures is a major concern. Offshore structures, mainly the oil and gas extraction infrastructure, are subjected to cyclic loading through currents and waves in addition to earthquakes and winds. Moreover, those steel structures can become structurally inadequate through incremental service loads, design or fabrication errors and material property degradation over time. Hence, these existing steel structures and those constructed in the future may require cyclic and seismic strengthening to mitigate the high risks of collapse and human casualties caused by cyclic and seismic loadings. There is however a clear research gap in the existing strategies for mitigating the adverse effects of cyclic and seismic loading in steel structures. Currently, the effectiveness of fibre reinforced polymer (FRP) strengthening to mitigate cyclic and seismic actions on reinforced concrete structures has been established through extensive research. Moreover, the FRP strengthening technique has been shown to be practical and effective to strengthen steel members under bending and fatigue loadings i.e. under cyclic loading within the elastic limit. However, the effectiveness of FRP strengthening of steel structures subjected to cyclic and seismic loadings has not yet been explored. This thesis is devoted to investigating the effectiveness of the FRP strengthening technique to mitigate the cyclic and seismic loading actions on steel structures, through an extensive research program involving both experimental testing and numerical analysis. Beam and column members, beam-column connections and frames are the key structural components of steel structures. Firstly, a series of full-scale experiments is carried out on the behaviour of the bare and carbon fibre reinforced polymer (CFRP) strengthened circular hollow section (CHS) steel members under monotonic and cyclic loadings. The experimental results showed that the CFRP strengthening technique is effective to enhance the cyclic performance of CHS steel members by improving the moment capacity, moment degradation behaviour, secant stiffness, energy dissipation capacity and ductility compared to bare steel CHS members. Besides, the ultimate moment capacity of the CHS members also improved under monotonic loading due to the CFRP strengthening. Finite element (FE) models of CFRP strengthened CHS members are developed in ABAQUS/CAE FE software, validated using the experimental results and then used to perform a detailed parametric study on the effects of the CFRP bond length, CFRP layer numbers, ratio of thickness of CFRP to the thickness of CHS, CHS member diameter-to-thickness ratio and steel grade on the performance of the CFRP strengthened CHS members under monotonic and cyclic loading. Additionally, the effectiveness of CFRP to strengthen the rectangular hollow section (RHS) members under cyclic loading is also investigated through a detailed parametric study. It is evident that the efficiency of CFRP strengthening increases with the ratio of thickness of CFRP to thickness of steel members and with the diameter-to-thickness ratio of steel members. Conversely, the efficiency of CFRP strengthening reduces with increases in steel grade. Theoretical models are developed for predicting the ultimate moment capacities of bare and CFRP strengthened steel members and the theoretical predictions agree reasonably well with the results from the numerical simulations. Secondly, two series of full-scale experiments are conducted to study the performance of CFRP and glass fibre reinforced polymer (GFRP) strengthened square hollow section (SHS) and CFRP strengthened I section steel beam-column connections. Results show that both FRPs (CFRP/ and GFRP) strengthening techniques considerably enhance the ultimate moment capacity, moment degradation behaviour, secant stiffness, energy dissipation capacity and plastic hinge behaviour of steel beam-column connections under cyclic loading. In addition, both CFRP and GFRP strengthened connections exhibit higher moment capacity, secant stiffness, energy dissipation capacity and ductility over the bare connections under monotonic loading as well. Moreover, CFRP strengthening shows better performance to enhance the ultimate strength whereas GFRP strengthening shows better performance to enhance ductility. The experimentally obtained moment capacities match reasonably well with the theoretically predicted moment capacities. Furthermore, a numerical FE modelling approach to simulate the cyclic responses of CFRP strengthened SHS beam-column connection has been developed in ABAQUS/CAE by validating with the experimental study and a detailed parametric study has been conducted on the behaviour of CFRP strengthened SHS beam-column connection under cyclic loading. Finally, a series of shake table tests on small-scale bare and CFRP strengthened rigid steel frames has been conducted to evaluate the seismic response of CFRP strengthened steel frames. The CFRP strengthening technique significantly reduced the lateral deflection by improving the stiffness of the steel frames. An FE model of the CFRP strengthened frame is developed in Strand7 FE software and validated using the shake table test results. The validated modelling techniques are then used in a parametric study on full-scale CFRP strengthened steel frames under seismic actions. Results indicate an improved seismic performance of the steel frame structure due to strengthening with CFRP and confirmed the effectiveness of the CFRP strengthening technique to mitigate seismic actions on steel structures. In summary, the development of the FRP strengthening technique for steel structures in the present study has contributed to new knowledge on the structural performance of the FRP strengthened onshore and offshore steel structures subjected to monotonic, cyclic and seismic loadings. In essence, this thesis has established the benefits of FRP strengthening and its application to mitigate the monotonic, cyclic and seismic actions on steel structures.
Chapter
Composite girders are extensively employed in the construction of various structures including bridges due to their potential to handle different types of loading conditions. While used in continuous spans of bridges, the lack of ability of concrete to take up tensile forces developed in the negative moment regions has been a matter of concern for a long. Ultra-high-performance concrete (UHPC) is said to have superior properties, including strength, toughness and ductility compared to Portland cement concrete. This paper presents the numerical study of the hogging moment region in a continuous steel–concrete composite girder, replacing the normal strength concrete (NSC) using UHPC under static loading. Finite element models of the girders were developed using ANSYS 18.0 software to simulate the behaviour of girders subjected to 3-point static loading. The flexural behaviour of girders with UHPC slabs was compared with those made up of normal strength concrete. The effects of parameters like slab width, depth and steel grade were also studied. Analysis showed that UHPC steel composite girders exhibited a higher flexural strength compared to normal steel–concrete composite girders. The load carrying capacity of the specimens was increased by 25–30% as the slab was modelled with UHPC instead of normal strength concrete. Optimal results were obtained when the UHPC slab was used in combination with alloy steel girders.KeywordsFinite element analysisHogging regionParametric studySteel girderUHPC
Article
Although the use of carbon fibre reinforced polymer (CFRP) materials for strengthening reinforced concrete structures and steel structures is well established, relatively few works have been reported for the strengthening of steel-concrete composite structures, especially at their hogging-moment region. In this paper, an experimental program consists of eight beam specimens with different degrees of shear connection, numbers of layers of CFRP sheets and strengthening methods was conducted. The experimental results show that adding CFRP sheets on the top of the concrete slab at hogging-moment region has a great effect on the structural performance in terms of ultimate loading capacity, load-deflection and load-slip responses, crack propagation, ductility, and failure mode, etc. The hybrid bonded FRP (HB-FRP) technique is firstly applied for the strengthening of steel-concrete structures at hogging-moment region in this study, and the advantages of the HB-FRP technique is proved through the comparisons with the externally bonded (EB) method. Based on the experimental observations, an analytical method for estimating the ultimate moment capacity of the strengthened composite beam at hogging-moment region is developed, for which the validity is verified against the experiment results.
Presentation
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This list contains the journal articles related to FRP-strengthened metallic structures, in seven categories: A. Bond B. Flexural Strengthening C. Compression Strengthening and Stability D. Dynamic and Cyclic Loading E. Durability F. Applications and Design Guides G. Structural Health Monitoring. The list is currently updated to 2021, and it will be renewed annually. To download the PDF file, please click "More" on the upper-right corner.
Chapter
Reuse of building components has the potential of maximizing the residual utility for the building materials in the End-of-Life (EoL) stage of a construction project. In this matter selective disassembly is an efficient method to retrieve reusable components from building assets. Unfortunately, the implementation of selective disassembly planning for buildings is still limited due to the challenge of generating accurate and correct analytical disassembly models for building archetypes. Therefore, the aim of this paper is to develop algorithms for the automatic determination of the necessary information for disassembly building models. The approach presented in this study uses BIM as the main platform and interface to implement the computational model. First, the necessary information for building disassembly models is investigated according to the Sequential Disassembly Planning for Buildings (SDPB) approach and the BIM parameters for disassembly models are suggested. Then, two algorithms are developed and tested in the Visual Programming Language (VPL) Dynamo to automatically populate the missing information in the BIM model. Finally, the results of the enriched BIM model are verified according to the analytical solution for disassembly models for buildings.KeywordsDisassembly modelBuilding information modelingDisassembly planning
Preprint
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Carbon fiber reinforced polymer (CFRP) materials have been effectively used as externally bonded sheets to repair damaged steel structures such as airplanes and ships. In this study, a series of double strap joints with different bonding lengths are considered and examined to experimentally and theoretically assess the effective bond length. Various models exist in the literature which are used to predict the strength of steel and CFRP joints under various loading conditions. Non-linear Lagrange stress method (NLS) which is a novel stress-based method for predicting the failure load values is presented for the first time. This approach is based on 2D and 3D linear elastic finite element analysis. Relying only on two experimental tests, the new approach proposed here can quickly and easily predict the failure load in steel/CFRP samples. In this methodology, it is assumed that the adhesive joint will fail as the normal stress along the adhesive mid-line reaches a predetermined value at a critical distance. In addition, experimental data on steel/CFRP joints gathered from the literature are compared to predictions using the NLS method. It was found that results from the theoretical predictions (NLS) were in good agreement with experimental tests conducted on double strap joints. It was also revealed that the average accuracy of the NLS method is superior to other methods such as cohesive zone model and Hart-Smith. The results revealed that under the best conditions, the NLS model is 5 times more accurate than existing models.
Article
Full-text available
Built mostly centuries ago, heritage buildings as well the more contemporary buildings of the last century, which have lost the bearing capacity often need restoration and strengthening, especially in seismic regions and in regions with shrinkage phenomena (subsidence region). The need of strengthening of the building constructions during exploitation appears mostly because of their premature wear as a result of technological influences and weathering, various damage and various other factors. Traditional methods of strengthening are effective, but in some cases not appropriate or not applicable for use. An example is the increase of the load-bearing structures of historical buildings, preserving the external appearance of which is the determining factor. In this case, the use of the discussed alternative methods can be justified alternative. Knowledge of the causes of defects and damage of structures allows to choose the best option of repairing or strengthening. The aim of the research is the evaluation of the structural performance of composite fibre-reinforced elements in the wider sector of the conservation of historical, architectonic and environmental heritage, as well the more contemporary buildings of the last century, which have lost of the bearing capacity focusing reliability indexes and the appearance of the structure. In the article was described and analyzed the existing traditional methods and the alternative methods of strengthening by FRP-materials (composite materials) such building structures as masonry, metal structures, reinforced concrete, and the computation in software ABAQUS. These procedures of strengthening building structures by FRP-materials in Ukraine are not widely used due to the lack of a regulatory framework that would regulate their use, as well because these materials are relatively expensive compared to the traditional ones. The article analyzed the existing methods of computation and design of the strengthening using FRP-materials, and the computation in software ABAQUS was performed with conclusions and recommendations based on results of the computation. The aim of the work was to review the technology and analyze the advantages and disadvantages of each of the strengthen methods that should be used when choosing effective solutions for strengthening building structures. In conclusion, the need for further study and researches was confirmed.
Thesis
Flexural strengthening of steel beams using CFRP laminates has gained popularity within the structural engineering community due to the many advantages it offers over traditional strengthening methods. Such advantages include ease of construction, resistance to corrosion and minimal disruption to traffic. Performance of such strengthened systems relies on the interfacial shear stress transfer mechanism of the bonded interface. Many existing studies have investigated the behaviour of CFRP-to-steel bonded joints under quasi-static monotonic loading, however, few studies have been carried out on understanding the behaviour of such bonded joints under cyclic loading. Since behaviour of the bonded interface is of critical importance to the performance of such strengthened structures, studies aimed at investigating the behaviour of CFRP-to-steel bonded interfaces under fatigue cyclic loading is urgently needed. This study presents an experimental and theoretical investigation into the behaviour of CFRP-to-steel bonded joints under quasi-static cyclic and fatigue loading. The experimental study presented consists of thirteen single shear pull-off tests of CFRP-to-steel bonded joints, covering three different bond thicknesses and three types of loading (quasi-static monotonic, quasi-static cyclic and fatigue loading). The results are discussed in terms of their failure mode, load-displacement behaviour, CFRP plate axial strain distribution, interfacial shear stress distribution and bond-slip behaviour. Based on the existing experimental data on behaviour of CFRP-to-steel bonded joints under quasi-static cyclic loading, a damaged plasticity type bond-slip relation was developed to model the constitutive behaviour of the bonded interface under quasi-static cyclic loading. This was further extended by developing a model for damage accumulation rate as a function of the applied slip range and number of cycles, to account for damage evolution under fatigue cyclic loading. Following the current studies on the constitutive behaviour of the bond in this research under fatigue loading, an experimental and numerical study aimed at investigating and modeling the performance of CFRP strengthened cracked steel plates under fatigue cyclic loading was performed. The double-sided strengthened notched steel plates were used to simulate the cracked steel plates. CFRP plates were bonded on both sides of the plate over the crack. In total, five plate tests were carried out. The results were discussed in terms of their failure mode, fatigue life extension, CFRP plate axial strain distribution, shear distribution, bond-slip behaviour and the collaboration of debonding and steel crack. Based on the proposed fatigue damage propagation model, a simplified numerical methodology was developed to simulate and predict the fatigue life of the CFRP strengthened cracked steel plates. This methodology was verified with the test results. To achieve this goal, several stages and tasks were accomplished and documented as three distinct research papers. The main achievements of this thesis can be summarized as: · The damaged elasticity assumption commonly used on CFRP-to-steel bonded interfaces is not valid and a damaged plasticity type model is required to accurately model the full-range behaviour of CFRP-to-steel bonded joints under cyclic loading. · To account for damaged plasticity observed during the experimental tests for the single-shear pull-off test specimens, the damaged parameter was defined as a function of the ratio between the total dissipated energy and the critical fracture energy. Function for the damage parameter was then obtained using the best fit curve for the experimental results. · The Damage propagation rate for the specimens under fatigue loading was defined as a function of the damage parameter, maximum and minimum slip values of the loading cycle. Empirical parameters of the defined function were then calibrated using the experimental data. · Based on the proposed fatigue damage propagation model, a simplified theoretical model was developed to predict the fatigue life of the CFRP strengthened cracked steel plates. The simplified theoretical model was verified using the experimental data. This model could be used to design for CFRP strengthened cracked steel plates under fatigue cyclic loading.
Article
Strengthening of steel beams utilizing FRP material has numerous advantages over traditional methods, which include bolting or welding new steel plates to the existing structure. Compared to other FRP material, Carbon FRPs (CFRPs) have been preferred for strengthening steel due to their higher stiffness. The emergence of High Modulus (HM) and Ultra-High Modulus (UHM) CFRP laminates, with an elastic modulus higher than that of steel, enables an increase in load transfer in steel beams prior to yielding of steel. Earlier research has highlighted the premature debonding failure of splice plates when used with UHM CFRP laminates. As an alternative to using a splice plate/laminate, this study investigates the performance of CFRP strip panels. The panels are designed so that continuity between two consecutive panels can be achieved through a finger joint. The panels are fabricated using narrow UHM CFRP strips (e.g., 5 mm, 10 mm) mounted on a fabric mesh, which is designed to maintain the necessary clear spacing between individual strips. Flexural tests are carried out under 4-point bending on steel wide flange beams. A 50 mm wide UHM CFRP laminate strengthened beam without laminate splicing is compared with the novel strip panel type splice strengthened girders. Two different strip widths of 5 mm and 10 mm are tested and all beams, strengthened with the same CFRP area, are evaluated against an un-strengthened control steel beam. The failure of the steel beam strengthened with the 50 mm UHM CFRP laminate was due to laminate rupture at a failure load (PFU-50mm) that is 39% larger than the load at which yielding initiated (Py) in the un-strengthened control beam (PFU-50mm = 1.39 Py). The tensile strains observed during rupture were 30% higher than the average maximum tensile strain observed in the material tests. The beams strengthened with UHM CFRP strip panels failed in debonding at the finger joint, with failure loads that are 27% and 26% larger than Py for the 10 mm and 5 mm strip panels respectively (PFU-10mm = 1.27 Py, PFU-5mm = 1.26 Py).
Article
In the present manuscript, the buckling behaviors of carbon fiber-reinforced polymer (CFRP) plates will be probed for the first time. The coupled influences of existence of symmetrically and asymmetrically distributed pores in the media and implementation of graphene platelets (GPLs) as the coating of the CFs on the mechanical responses of the system will be covered, too. The GPL coatings will construct a GPLs-reinforced interphase, which helps the structure to tolerate greater buckling loads. The effective stiffness of the system will be enriched utilizing a micromechanical procedure regarding the influence of available porosities in the material. Afterward, the principle of virtual work will be used for the goal of deriving the governing equations of the plate-type structure based upon the expansion of the displacement field of a refined-type higher-order shear deformation theory (HSDT). At the end, the buckling load of the system will be obtained solving the eigenvalue buckling problem within the framework of the Navier’s well-known analytical solution for the case of which all of the edges are simply supported. The validity of the proposed investigation is examined, and a mentionable agreement between the results of this work and those available in the open literature is observed. The generated results indicate the crucial role of the GPLs-reinforced interphase on the stability endurance of the CFRP plate.
Article
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Steel-concrete composite beam with profiled steel sheet has gained its popularity in the last two decades. Due to the ageing of these structures, retrofitting in terms of flexural strength is necessary to ensure that the aged structures can carry the increased traffic load throughout their design life. The steel ribs, which presented in the profiled steel deck, limit the use of shear connectors. This leads to a poor degree of composite action between the concrete slab and steel beam compared to the solid slab situation. As a result, the shear connectors that connects the slab and beam will be subjected to higher shear stress which may also require strengthening to increase the load carrying capacity of an existing composite structure. While most of the available studies focus on the strengthening of longitudinal shear and flexural strength separately, the present work investigates the effect of both flexural and longitudinal shear strengthening of steel-concrete composite beam with composite slab in terms of failure modes, ultimate load carrying capacity, ductility, end-slip, strain profile and interface differential strain. The flexural strengthening was conducted using carbon fibre reinforced polymer (CFRP) or steel plate on the soffit of the steel I-beam, while longitudinal shear capacity was enhanced using post-installed high strength bolts. Moreover, a combination of both the longitudinal shear and flexural strengthening techniques was also implemented (hybrid strengthening). It is concluded that hybrid strengthening improved the ultimate load carrying capacity and reduce slip and interface differential strain that lead to improved composite action. However, hybrid strengthening resulted in brittle failure mode that decreased ductility of the beam.
Chapter
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Steel-concrete composite girders are widely used in the construction of bridges and buildings. However when they are provided in continuous spans, a loss of strength and composite action will be occurring at the hogging moment region due to the development of tension in concrete and compression in steel. Limited works have been done to study this shortcoming in these widely used girders. Carbon fiber reinforced polymer (CFRP), is found to have lot of untapped potential for improving the strength of girders. This paper presents an analytical investigation into the behavior of composite girders strengthened in hogging moment region using CFRP. Effect of different arrangements and thickness of CFRP laminates are also being compared for different geometries. CFRP was found effectively improve the strength of composite girders in the negative moment regions especially when used in the form of strips.
Chapter
The number of civil infrastructures which have deteriorated and no longer fulfill the requirements of safety standards is continuously increasing day by day. Over the past few decades, there has been increasing interest in applying adhesively bonded composites to repair existing and/or strengthen new civil engineering structures. Extensive research has been conducted on Fiber Reinforced Polymer (FRP) strengthening of concrete structures, whereas relatively less work has been done on FRP strengthening of steel structures. Among the FRP materials available, Carbon Fiber Reinforced Polymers (CFRP) were found to be the most suitable for strengthening steel structures because of their well known high mechanical properties and high strength to weight ratio. This paper presents an experimental investigation on the effect of CFRP strengthening in the load carrying capacity, stiffness and deformation characteristics of undamaged and damaged steel beams. The effect of end anchorage on flexural strengthening of steel beam is also investigated.
Article
Flexural strengthening of steel-concrete composite beams with fiber-reinforced polymer (FRP) materials has recently become a topic of considerable interest, due to the many advantages it may offer in both enhancing the design prospects of new structures and restoring the functioning condition of deficient existing structures. During the past two decades, a substantial number of experimental, numerical and analytical studies has been concerned with this topic. Although these studies have provided significant insights into the problem, a lack of simplified methods for assessing the FRP-strengthening effects in a quantitative manner still exists. Motivated by this need, a study that seeks to establish a sound understanding of the mechanics of the problem – which is a fundamental component for the development of simple and reliable analysis approaches – is presented in this paper. The basis of the study is the development of a new analytical method for the prediction of the moment-curvature relationship and the overall flexural response of FRP-strengthened steel-concrete beams, by assuming perfect bond between the constitutive components. The method only requires accessible spreadsheet calculations, which makes it both suitable for routine use in design practice and particularly useful for the scientific study of the problem. The new method is first validated against available experimental results and it is then employed in conducting a systematic parametric study, from which several conclusions of essential practical significance for the optimum use of FRP composites in strengthening the flexural behaviour of steel-concrete composite beams are derived.
Book
Full-text available
The textbook provides main information about construction materials (concrete, reinforced concrete, stone), their physical and mechanical properties, analysis of reinforced concrete and stone structures for strength, rigidity and crack resistance. The book covers the features of methods of calculation, design and experimental research of reinforced concrete and stone structures, features of methods of calculation of structures in the construction of airports. The scientific monograph can be useful for scientific and pedagogical workers and engineers, doctoral students, postgraduates and students of technical universities who will study in the specialty 192 "construction and civil engineering" and anyone interested in airport design and construction. More detailed bibliographic information about the book is available at the German National Library in Berlin, Leipzig and Frankfurt am Main.
Article
This paper briefly reviews the results of NCHRP Project 12-28(4), Methods of Strengthening Existing Highway Bridges. The initial task was a thorough review of international literature to determine strengthening procedures currently being used and to investigate innovative ideas now being considered. The types of structures that show the most need for cost-effective strengthening were identified. A procedure for determining equivalent uniform annual costs was developed to assist the engineer in determining whether to strengthen or replace a given bridge. The culmination of the study was the development of a strengthening manual for practicing engineers. The eight sections of that manual, which contain different strengthening procedures, are briefly summarized.
Article
This paper describes the technique of increasing beam strength by means of externally applied reinforcing steel plates, bonded by means of epoxy-resin adhesive. Tests methods, application data, and some indication of preferred resin formulation are given. Steel plates are bonded to the beams by means of epoxy-resin paste adhesive. During curing of the resin the plates are held in place by clamps and/or bolts. This provides an inexpensive method of restoring or upgrading the strength of damaged or substrength concrete bridge and similar beams.
Article
The demand for the use of carbon-fiber-reinforced plastics (CFRP) in rehabilitation of deteriorating infrastructure is increasing worldwide. The design characteristics of reinforced concrete or steel members can be enhanced significantly by epoxy bonding CFRP laminates to the critically stressed tension areas. There is, however, a concern regarding possible galvanic corrosion when carbon and steel are bonded together. This paper presents the result of a study on the galvanic corrosion between CFRP laminates and steel. A total of 38 specimens made of steel and carbon fibers were prepared and tested. Two simulated aggressive environments and three different amounts of epoxy coating were used in addition to samples with no coating at all. Further- more, the effect of the sizing agent on the galvanic corrosion rate was investigated, and three different solvents were used to remove the sizing agents from the surface of the carbon fibers. Potentiodynamic polarization and galvanic corrosion tests were conducted. The results of the experiments showed the existence of galvanic cor- rosion; however, the rate of such corrosion could be decreased significantly by epoxy coating.
Article
Fatigue cracking was seldom found in welded highway and railroad bridges from the time of their introduction in the 1950s until the late 1960s. The fatigue design specifications used in that era were developed from a limited knowledge base and largely with small-scale specimens that simulated welded details. During the AASHO Road Test in 1960 fatigue cracks were observed to develop in cover-plated steel bridge beams as a result of the heavy loads and high stress ranges. This observation subsequently resulted in a series of experimental studies supported by NCHRP starting in 1967. The laboratory studies with full-scale details were designed to evaluate the significance of many factors thought to influence fatigue resistance, including loading history (and associated stress states including residual stresses), type of steel, design details, and quality of fabrication. These studies indicated that small-scale specimens overestimated fatigue resistance and that only the stress range for a given detail was critical. As a result fatigue resistance design provisions in use since the 1950s were inadequate and overly optimistic, particularly at longer lives, because the assumption of a fatigue limit of 2 million cycles proved to be incorrect. The results of laboratory studies with full-size specimens and their impact on changing the concept of fatigue design and the bridge fatigue design provisions used for highway and railroad bridges today are reviewed. During the 1970s and 1980s fatigue cracking associated with low-fatigue-strength details (Categories E and E′), such as cover plates and lateral gusset plates, increased. Cracks were also found in transverse groove welds, particularly in attachments such as longitudinal stiffeners, gusset plates and even flange splices. These groove weld cracks generally occurred because large defects were inadvertently fabricated into the welded joint. The occurrence of these cracks was found to be predictable and in agreement with the laboratory fatigue resistance results. The 1970s also exposed an unexpected source of cracking due to the distortion of small web gaps that were frequently used in welded bridge structures. Web gap cracking continues to develop in a wide range of bridge types. It is the source of most fatigue cracks in steel bridges. Existing bridges that are susceptible to fatigue cracks or that develop fatigue cracks at primary details or from web gap distortion are easily repaired or retrofitted to ensure long-term performance. Examples of such repairs are reviewed. The future is bright for welded bridges because the knowledge base and current design provisions make it possible to design and build fatigue-resistant bridges.
Article
Article
An example of the use of bonded steel plates to strengthen a motorway bridge complex is described. Full-scale loading tests demonstrated that the required structural improvements had been achieved, and associated laboratory tests confirmed short-term strengthening effects. Uncertainties about long-term durability have led to an extensive programme of weathering tests. Early results from small-scale tests indicate the possibility of slightly reduced bond efficiency due to internal corrosion and indicate the need for improved anti-corrosion treatment to ensure a long trouble-free life.
Article
Introduction Axially Loaded Short Columns Eccentrically Loaded Short Columns with Uniaxial Bending Eccentrically Loaded Short Columns with Biaxial Bending Slender Columns References
Methods of strengthening existing highway bridges.'' NCHRP 293, Fig. 16. Failure modes: a concrete crushing; b composite edge snapping; and c bond failure
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Klaiber, F. W., Dunker, K. F., Wipf, T. J., and Sanders, W. W. 1987. ''Methods of strengthening existing highway bridges.'' NCHRP 293, Fig. 16. Failure modes: a concrete crushing; b composite edge snapping; and c bond failure JOURNAL OF STRUCTURAL ENGINEERING / JANUARY 2003 / 39
Copyright ASCE. For personal use only; all rights reservedApplication of adhesive to steel bridges
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Copyright ASCE. For personal use only; all rights reservedRehabilitation of steel bridge girders through the application of advanced composite material
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Count of deficient highway bridges The Office of Bridge Technology, The Federal Highway Administration
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Raithby, K. ͑1980͒. ''External strengthening of concrete bridges with bonded steel plates.'' Supplementary Rep. 612, Transport and Road Research Laboratory, Dept. of Environment, Crowthorn, England, 16 –18.
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Sen, R., and Liby, L. 1994. ''Repair of steel composite bridge sections using carbon fiber reinforced plastic laminates.'' FDOT-510616, Florida Dept. of Transportation, Tallahassee, Fla. Tavakkolizadeh, M., and Saadatmanesh, H. 2001. ''Galvanic corrosion of carbon and steel in aggressive environments.'' J. Compos. Constr., 53, 200–210.
Application of adhesive to steel bridges
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Albrecht, P., Sahli, A., Crute, D., Albrecht, Ph., and Evans, B. 1984. ''Application of adhesive to steel bridges.'' FHWA-RD-84-037, The Federal Highway Administration, Washington, D.C., 106-147.
Repair of steel composite bridge sections using carbon fiber reinforced plastic laminates
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Sen, R., and Liby, L. 1994. ''Repair of steel composite bridge sections using carbon fiber reinforced plastic laminates.'' FDOT-510616, Florida Dept. of Transportation, Tallahassee, Fla. Tavakkolizadeh, M., and Saadatmanesh, H. 2001. ''Galvanic corrosion of carbon and steel in aggressive environments.'' J. Compos. Constr., 53, 200-210.
Composite material handbook 2nd Ed
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