Experimental Study on the Flexural Behaviour of a Novel Concrete Filled Hybrid Beams Reinforced with GFRP and Steel Bars

Ferhat Aydın 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11

This study presents the flexural performances of hybrid beams where glass fibre reinforced plastic (GFRP) box profile, concrete, steel or GFRP bars were used together. By conducting flexural tests on beams of varying properties produced for this purpose, the minimum reinforcement effects in GFRP profile-concrete beams were experimentally presented. Beam series of two sizes, as 74−74−500 mm small beams and 100−100−1,500 mm large beams, and varying combinations were produced. In addition, some properties of GFRP box profiles were improved. Following the tests conducted on small beams, the number of large beam samples was reduced and while steel bars were used in some beams, GFRP bars were used in others. The hybrid beams were compared with reinforced concrete beams have the same dimensions in large beams. On the basis of the results obtained from the tests it was determined that the flexural performances of steel reinforced hybrid beams increased at a higher level. Flexural strength of the improved hybrid beams increased by about two times compared to the classical reinforced concrete beams. Fracture toughness of the hybrid beams improved 53%.

An Experimental Study on Inelastic Lateral-Torsional Buckling Strength of Singly Symmetric Stepped I-Beams Having Compact and Non-Compact Flange Sections

Albert Surla,Jong Sup Park 한국방재학회 2015 한국방재학회 학술발표대회논문집 Vol.14 No.-

Recently, as the level of market competition in the structural engineering field continues to rise, structural designers are finding other ways to make their designs stand out. One way of doing that is to make the designs more economical without sacrificing efficiency. As a result, the use of stepped beams and the studies involving it has become more common. Stepped beams are beams that have a sudden increase in cross section along its length. The change in cross section is made by increasing the width and/or the thickness of the flanges along a certain length while maintaining the dimensions of the web. Most of the studies involving lateral torsional buckling of stepped beams are focused on developing equations and studying the effects of symmetry. However, the studies involving actual test experiments are still very limited. Thus, this study has three main objectives. The first objective of this study is to give a brief historical overview on the series of studies involving the lateral torsional buckling capacity of stepped beams and give an idea on its current state of the art. The second objective is to determine if the intuitive expectation that the lowest critical moment always corresponds to uniform bending moment holds true for stepped beams. The degree of symmetry is varied and several loading conditions are observed. The third objective of this study is to determine the actual inelastic lateral torsional buckling capacity of doubly stepped singly symmetric I-beams having compact and non-compact flange sections subjected to two point loading condition and to use the results obtained to determine the applicability of previously proposed equations in predicting the buckling strength of stepped beams. The results are obtained by conducting actual destructive tests on doubly stepped I-beams using a universal testing machine and running simulation tests using the finite element program, ABAQUS. The main factors that are considered for the experimental and finite element analysis are the degree of beam symmetry, the loading condition, the supports, the stepped beam factors and the unsupported length. The degree of symmetry of all the stepped beams analyzed is fixed at 0.7. The unsupported lengths of the beams analyzed are 3 meters and 4 meters. The results obtained from the analysis are compared with the results from design specifications to determine the effects of steps and from proposed design equations to determine the equations’ applicability and safety. Finally, the results revealed that the stepped beams did have an increase in lateral torsional buckling capacity in comparison with the prismatic beams and that the proposed equations are suitable to be used in predicting the strength of stepped beams having compact flanges under the observed loading condition. However, for beams having non-compact flanges, the previously proposed equations produced over conservative results. Further study can also be made on stepped beams with varying degree of symmetries, loading conditions, boundary conditions and stepped beam parameters.

CFRP strengthening of steel beam curved in plan

Amir Hamzeh Keykha 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.5

Nowadays, one of the practical, fast and easy ways to strengthen steel elements is the use of Carbon Fiber Reinforced Polymer (CFRP). Most previous research in the CFRP strengthening of steel members has carried out on straight steel members. The main difference between horizontal curved beams and straight beams under vertical load is the presence of torsional moment in the horizontal curved beams. In the other words, the horizontal curved beams are analyzed and designed for simultaneous internal forces included bending moment, torsional moment, and shear force. The horizontal curved steel beams are usually used in buildings, bridges, trusses, and others. This study explored the effect of the CFRP strengthening on the behavior of the horizontal curved square hollow section (SHS) steel beams. Four specimens were analyzed, one non-strengthened curved steel beam as a control column and three horizontal curved steel beams strengthened using CFRP sheets (under concentrated load and uniform distributed load). To analyze the horizontal curved steel beams, three dimensional (3D) modeling and nonlinear static analysis methods using ANSYS software were applied. The results indicated that application of CFRP sheets in some specific locations of the horizontal curved steel beams could increase the ultimate capacity of these beams, significantly. Also, the results indicated when the horizontal curved steel beams were under distributed load, the increase rate in the ultimate capacity was more than in the case when these beams were under concentrated load.

An Experimental Study on the Shear Strengthening of Reinforced Concrete Deep Beams with Carbon Fiber Reinforced Polymers

Muhammad Afaq Javed,Muhammad Irfan,Sumera Khalid,Yulong Chen,Saeed Ahmed 대한토목학회 2016 KSCE Journal of Civil Engineering Vol.20 No.7

In recent years, Fiber Reinforced Polymers (FRP) have emerged as useful materials for structural strengthening and rehabilitation. The main aspire of this research is towards evaluating the efficiency of Carbon Fiber Reinforced Polymers (CFRP) in enhancing the shear strength of deep beams. The research work included construction and testing of eight (08) reinforced concrete deep beams. Two of the beams, designated as control beams, were without any shear reinforcement. Remaining six beams were divided into three groups, with each group having two identical beams. Beams in one of these groups were strengthened with conventional type of steel web reinforcement. Remaining two groups were strengthened externally by CFRP sheets with different orientations of CFRP. Magnitude of load causing shear cracks to initiate, and the failure load of each beam was recorded. Significant increase in overall load carrying capacities was observed with both CFRP sheets and web steel reinforcement. CFRP was found to be considerably effective in delaying the initial appearance of shear cracks, thereby improving the serviceability limit state of beams. Beams with CFRP orientation perpendicular to the shear cracks showed higher increment in shear strength. In conclusion, CFRP laminates could effectively be used to strengthen existing RC structures deficient in shear strength, and also to reduce/replace internal steel web reinforcement in new RC structures. Material cost comparison of CFRP reinforced beams with conventional web reinforcement is presented, and the general cost effectiveness of structural rehabilitation by means of CFRP is also discussed.

Influence of trapezoidal and sinusoidal corrugation on the flexural capacity of optimally designed thin-walled beams

Ferhat Erdal,Osman Tunca,Harun Taylan,Ramazan Ozcelik,Huseyin Sogut 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.84 No.1

Major engineering requirements and technological developments in the steel construction industry are discussed to support a new innovative system, namely corrugated web beams, for future structural projections. These new-generation steel beams, fabricated as welded plate girders with corrugated webs, are designed to combine large spans with very low weight. In the present study, the flexural capacity of optimally designed trapezoidal and sinusoidal corrugated web beams was aimed at. For this purpose, the new metaheuristic methods, specifically hunting search and firefly algorithms, were used for the minimum weight design of both beams according to the rules of Eurocode EN 1193 15 and DASt-Ri 015. In addition, the strengthening effects of the corrugation geometry at the web posts on the load capacity of fabricated steel beams were tested in a reaction frame. The experimental tests displayed that the lateral capacity of trapezoidal web beams is more durable under flexural loads compared to sinusoidal web beams. These thin-walled beams were also simulated using a 3-D finite element model with plane strain to validate test results and describe the effectiveness of the ABAQUS software.

The comparative analysis of optimal designed web expanded beams via improved harmony search method

Erdal, Ferhat Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.4

This study aims at comparing the optimum design of two common types open web expanded beams: with hexagonal openings, also called castellated beams and beams with circular openings referred to as cellular beams. The minimum weights of both beams are taken as the objective functions while the design constraints are respectively implemented from The Steel Construction Institute Publication Numbers 5 and 100. The design methods adopted in these publications are consistent with BS5950 parts. The formulation of the design problem considering the limitations of the above mentioned turns out to be a discrete programming problem. Improved harmony search algorithm is suggested to compare the optimum design of mentioned web-expanded beams to analysis the performance of both beams. The design algorithms based on the technique select the optimum Universal Beam sections, dimensional properties of hexagonal and circular holes and total number of openings along the beam as design variables.

The comparative analysis of optimal designed web expanded beams via improved harmony search method

Ferhat Erdal 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.4

This study aims at comparing the optimum design of two common types open web expanded beams: with hexagonal openings, also called castellated beams and beams with circular openings referred to as cellular beams. The minimum weights of both beams are taken as the objective functions while the design constraints are respectively implemented from The Steel Construction Institute Publication Numbers 5 and 100. The design methods adopted in these publications are consistent with BS5950 parts. The formulation of the design problem considering the limitations of the above mentioned turns out to be a discrete programming problem. Improved harmony search algorithm is suggested to compare the optimum design of mentioned web-expanded beams to analysis the performance of both beams. The design algorithms based on the technique select the optimum Universal Beam sections, dimensional properties of hexagonal and circular holes and total number of openings along the beam as design variables.

Flexural strengthening of RC beams using externally bonded aluminum plates: An experimental and numerical study

Elsamak, Galal,Fayed, Sabry Techno-Press 2021 Advances in concrete construction Vol.11 No.6

This research investigated the flexural strengthening of RC beams using Aluminum plates (AP). An experimental program including 8 RC beams were carried out. The width and depth of the beam were 150 and 300 mm respectively while the effective span of the beam was 1560 mm. The tensile reinforcement ratios of the beams were 0.38 and 0.548%. The external APs ratios (the cross sectional area of AP to the beam cross sectional area) were 0.10, 0.37 and 0.74% while the AP length to the beam length was 0.93. A Finite element analysis (FEA) was investigated to study many variables that influenced on the ultimate load and the behavior of the AP-strengthened beams such as AP length, using shear connectors, using various techniques of the end anchorages and using anchored/unanchored U-shaped APs. It was noticed that the improvement ratios of the ultimate load and the ductility of strengthened beams with tensile reinforcement ratio of 0.38% was better than the beams with tensile reinforcement ratio of 0.548%. The AP length to the beam span ratio had a significant effect on the ultimate load, the ductility and the failure mode of the beams. The ultimate deflection and the ultimate load of the AP strengthened beams that used shear connectors increased by 165 and 54 % respectively compared to the beam without shear connectors. Using U-shaped AP jacket accompanied with end anchorages enhanced the ultimate load by 109%. The ultimate load of the beams with bolted U-shaped AP jacket increased by 128%.

Evaluation of shear capacity of FRP reinforced concrete beams using artificial neural networks

Nehdi, M.,El Chabib, H.,Said, A. Techno-Press 2006 Smart Structures and Systems, An International Jou Vol.2 No.1

To calculate the shear capacity of concrete beams reinforced with fibre-reinforced polymer (FRP), current shear design provisions use slightly modified versions of existing semi-empirical shear design equations that were primarily derived from experimental data generated on concrete beams having steel reinforcement. However, FRP materials have different mechanical properties and mode of failure than steel, and extending existing shear design equations for steel reinforced beams to cover concrete beams reinforced with FRP is questionable. This paper investigates the feasibility of using artificial neural networks (ANNs) to estimate the nominal shear capacity, Vn of concrete beams reinforced with FRP bars. Experimental data on 150 FRP-reinforced beams were retrieved from published literature. The resulting database was used to evaluate the validity of several existing shear design methods for FRP reinforced beams, namely the ACI 440-03, CSA S806-02, JSCE-97, and ISIS Canada-01. The database was also used to develop an ANN model to predict the shear capacity of FRP reinforced concrete beams. Results show that current guidelines are either inadequate or very conservative in estimating the shear strength of FRP reinforced concrete beams. Based on ANN predictions, modified equations are proposed for the shear design of FRP reinforced concrete beams and proved to be more accurate than existing equations.

The influence of strengthening the hollow steel tube and CFST beams using U-shaped CFRP wrapping scheme

Ahmed W. Al-Zand,Emad Hosseinpour,Wan Hamidon W. Badaruzzaman 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.2

This study investigated the behaviour of the simply supported hollow steel tube (HST) beams, either concrete filled or unfilled when strengthened with carbon fibre reinforced polymer (CFRP) sheets. Eight specimens with varied tubes thickness (sections classification 1 and 3) were all tested experimentally under static flexural loading, four out of eight were filled with normal concrete (CFST beams). Particularly, the partial CFRP strengthening scheme was used, which wrapped the bottom-half of the beams cross-section (U-shaped wrapping), in order to use the efficiency of high tensile strength of CFRP sheets at the tension stress only of simply supported beams. In general, the results showed that the CFRP sheets significantly improved the ultimate strength and energy absorption capacities of the CFST beams with very limited improvement on the related HST beams. For example, the load and energy absorption capacities for the CFST beams (tube section class 1) were increased about 20% and 32.6%, respectively, when partially strengthened with two CFRP layers, and these improvements had increased more (62% and 38%) for the same CFST beams using tube class 3. However, these capacities recorded no much improvement on the related unfilled HST beams when the same CFRP strengthening scheme was adopted.