scholarly journals Numerical Investigation of Behavior of RC Columns Strengtheneg with RC Jacket

2019 ◽  
Vol 2 (2) ◽  
pp. 257-264
Author(s):  
M. Burhan Navdar ◽  
Naci Caglar
Keyword(s):  
Load Capacity ◽  
Concrete Strength ◽  
Experimental Studies ◽  
Element Model ◽  
Transverse Reinforcement ◽  
Structural Elements ◽  
Rc Columns ◽  
Existing Structures ◽  
Laboratory Facilities ◽  
Earthquake Performance

Strengthening of structural elements which are insufficient in terms of earthquake performance is very important for the safety of existing structures. Nowadays, one of the most commonly used methods is strengthening such members with RC jacketing. Several experimental studies have been conducted in the literature to investigate behavior of structural elements reinforced with RC jacketing. Moreover, numerical studies are frequently preferred due to the high cost of experimental studies and the limited availability of laboratory facilities. In this study, a finite element model has been created with OpenSees program in order to investigate the behavior of strengthened RC columns with jacketing. Later, the accuracy of the model has been verified successful by the experimental results selected from the literature. By using that verified model, the effects of concrete strength and amount of spacing of transverse reinforcement used on the jacketing part on reinforced column behavior were investigated. As a result of the study, it is deduced that the change in the concrete strength and amount of transverse reinforcement results in a significant change in ductility, load capacity and rigidity of the reinforced concrete columns.

Effect of Tow Sheet Composite Wrap Architecture on Strengthening of Concrete Due to Confinement: I—Experimental Studies

1995 ◽  
Vol 14 (9) ◽  
pp. 1008-1030 ◽  
Author(s):  
Ian Howie ◽  
Vistasp M. Karbhari
Keyword(s):  
Concrete Strength ◽  
Experimental Studies ◽  
Load Carrying Capacity ◽  
Structural Elements ◽  
New Techniques ◽  
Column Type ◽  
Load Carrying ◽  
Concrete Shell ◽  
Original Construction ◽  
Stub Columns

Worldwide there is a need for the renewal of infrastructure because of age, deterioration, misuse, lack of timely repair and maintenance, use of improper materials and/or techniques in the original construction, and even changing needs. Notwithstanding the need for retrofit and repair methods for column-type structural elements, there is also a need for new techniques that would increase the confining action of concrete, as well as enhance the load-carrying capacity and ductility of such structures from a strengthening, rather than a seismic, viewpoint. This study investigates the use of carbon-fiber-reinforced jackets applied to concrete stub columns through the use of tow-sheet-type fabric forms. The primary emphasis is on the investigation of orientation and thickness effects of the composite wraps on the load-carrying efficiency and enhanced ductility of the new structural elements. It was seen that the predominant use of hoop reinforcement provides significant enhancement in concrete strength through confining action and also offers the potential for fabrication of concrete shell-type elements that would enable reinforcing action without the use of steel and the attending problems of corrosion.

scholarly journals Post-strengthening of reinforced concrete beams with prestressed CFRP strips. Part 1: analysis under static loading

2012 ◽  
Vol 5 (3) ◽  
pp. 343-361
Author(s):  
M. R. Garcez ◽  
G. L. C. P. Silva Filho ◽  
Urs Meier
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Existing Structures ◽  
Flexural Tests ◽  
Strengthening Technique ◽  
Epoxy Matrices

Different FPR post-strengthening techniques have been developed and applied in existing structures aiming to increase their load capacity. Most of the FRP systems used nowadays consist of carbon fibers embedded in epoxy matrices (CFRP). Regardless of the advantages and the good results shown by the CFRP post-strengthen technique, experimental studies show that, in most cases, the failure of post-strengthened structures is premature. Aiming to better use the tensile strength of the carbon fiber strips used as post-strengthening material, the application of prestressed CFRP strips started to be investigated. The main purpose of this paper is to analyze the effects of the composite prestressing in the performance of the CFRP post strengthening technique. The experimental program was based on flexural tests on post-strengthened reinforced concrete beams subjected to static - part 1 and cyclic - part 2 loading. Experimental results allowed the analysis of the quality and shortcomings of post-strengthen system studied, which resulted in valuable considerations about the analyzed post-strengthened beams.

scholarly journals Behavior of Glulam Beams Strengthened in bending with BFRP Fabrics

2021 ◽  
Vol 31 (2) ◽  
pp. 1-14
Author(s):  
Agnieszka Wdowiak-Postulak ◽  
Grzegorz Świt
Keyword(s):  
Bending Strength ◽  
Load Capacity ◽  
Experimental Studies ◽  
Basalt Fiber ◽  
Fiber Reinforced Polymers ◽  
Structural Elements ◽  
Basalt Fibers ◽  
Reinforced Polymers ◽  
Glued Laminated Timber ◽  
Environmentally Friendly Method

Abstract The article presents results of an experimental studies on reinforcement of pine beams made from glued laminated timber with subsurface basalt fibers (BFRP). An experimental research program was presented, in which the bending strength of glued laminated timber of middle and lower quality class was increased after using BFRP basalt fabrics. Thanks to the use of BFRP reinforcement, an average load capacity increased by 47% and stiffness by 6% in comparison to non-reinforced elements. Based on the research, it was found that the use of BFRP basalt fabrics is an effective method for strengthening damaged wooden elements. Thus, it is an environmentally friendly method of improving the static work of structural elements by combining wood with other natural materials such as basalt fiber reinforced polymers.

scholarly journals Post-strengthening of reinforced concrete beams with prestressed CFRP strips: part 2: analysis under cyclic loading

2012 ◽  
Vol 5 (4) ◽  
pp. 420-439
Author(s):  
M. R. Garcez ◽  
L. C. P. Silva Filho ◽  
Urs Meier
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Existing Structures ◽  
Flexural Tests ◽  
Strengthening Technique ◽  
Epoxy Matrices

Different FPR post-strengthening techniques have been developed and applied in existing structures aiming to increase their load capacity. Most of the FRP systems used nowadays consist of carbon fibers embedded in epoxy matrices (CFRP). Regardless of the advantages and the good results shown by the CFRP post-strengthen technique, experimental studies show that, in most cases, the failure of post-strengthened structures is premature. Aiming to better use the tensile strength of the carbon fiber strips used as post-strengthening material, the application of prestressed CFRP strips started to be investigated. The main purpose of this paper is to analyze the effects of the composite prestressing in the performance of the CFRP post strengthening technique. The experimental program was based on flexural tests on post-strengthened reinforced concrete beams subjected to static - part 1 and cyclic - part 2 loading. Experimental results allowed the analysis of the quality and shortcomings of post-strengthen system studied, which resulted in valuable considerations about the analyzed post-strengthened beams.

scholarly journals Numerical Evaluation of Reinforced Concrete Columns Retrofitted with FRP for Blast Mitigation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jing Dong ◽  
Junhai Zhao ◽  
Dongfang Zhang
Keyword(s):  
High Strength ◽  
Element Model ◽  
Blast Mitigation ◽  
Rc Columns ◽  
Existing Structures ◽  
Frp Composites ◽  
Blast Response ◽  
Proposed Model ◽  
Comprehensive Comparison ◽  
Result Analysis

Fiber reinforced polymer (FRP) material is commonly applied in retrofitting structures due to the advantages of high strength and well corrosion resistance. Previous studies indicated that retrofitting with FRP sheet was an effective way for protecting the existing structures to resist the blast loads, but little research made comprehensive comparison study on the blast response of RC columns with different retrofitting strategies. This paper proposed a series of FRP retrofitting strategies and evaluated their effect on blast mitigation using numerical analysis approach. Comparison studies were conducted on the effect of FRP type, FRP thickness, and retrofitting mode on blast mitigation. A finite element model of RC columns retrofitted with FRP under blast loading was developed. The model considered the strain rate effect of steel and concrete and the orthotropic property of FRP composites. The reliability of the proposed model was validated against the data from a field blast test. Based on the verified model, the blast responses of RC columns with different retrofitting strategies were numerically investigated. According to the result analysis, appropriate FRP type, FRP thickness, retrofitting mode, and retrofitting length were recommended.

Experimental Studies on the Mechanical Performances of Corroded Reinforced Concrete Columns Retrofitted with FRP

2013 ◽  
Vol 405-408 ◽  
pp. 726-730 ◽  
Author(s):  
Ying Wu Zhou ◽  
Ling Yi Wu ◽  
Li Li Sui ◽  
Feng Xing
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Load Capacity ◽  
Experimental Studies ◽  
Concrete Columns ◽  
High Corrosion Resistance ◽  
Rc Columns ◽  
Corrosion Rates ◽  
Externally Bonded ◽  
Mechanical Performances

Due to the superiority of high corrosion resistance of FRP materials, more and more attentions have been attracted to the retrofitting of corroded reinforced concrete (RC) columns with FRP. This paper thus presents an experimental study on mechanical performances of corroded RC columns strengthened with FRP, focusing on the effects of different corrosion rates of the reinforcements and the retrofitting scheme. The effectiveness of externally bonded FRP to the corroded RC column to increase its load capacity and ductility is tested; the mechanical performances of the strengthened columns are theoretically investigated. The results indicate that the effectiveness of retrofitting the existing corroded RC columns with FRP jackets is much more significant than that of retrofitting the newly built columns with FRP jackets and externally wrapped with FRP jackets is much more effective to improving the structural performances of heavily corroded columns.

CREDO RADON UA – INFORMATION MODEL FOR CALCULATION OF ROAD CONSTRACTION

2019 ◽  
pp. 34-42
Author(s):  
Volodymyr Karedin ◽  
Nadiya Pavlenko
Keyword(s):  
Design Process ◽  
Static Loading ◽  
Computer Aided Design ◽  
Experimental Studies ◽  
Construction Materials ◽  
Residual Deformation ◽  
Road Construction ◽  
Information Support ◽  
Existing Structures ◽  
Road Pavement

CREDO RADON UA software provides an automated calculation of the strength of the pavement structures of non-rigid and rigid types, as well as the calculation of the strengthening of existing structures. In the article, one can see the main features and functionality of the CREDO RADON UA software, the main points in the calculations according to the new regulations. Information support of the design process includes necessary databases, informational and helping materials that make up the full support of the pavement design process. The concept of CREDO RADON UA 1.0 software is made on the use of elasticity theory methods in calculations of initial information models of pavements. Performing optimization calculations, the roadwear in CREDO RADON UA is designed in such a way that no unacceptable residual deformation occurs under the influence of short-term dynamic or static loading in the working layer of the earth bed and in the structural layers during the lifetime of the structure. The calculation algorithms were made in accordance with the current regulatory documents of Ukraine. CREDO RADON UA software allows user to create information bases on road construction materials and vehicles as part of the traffic flow for calculations. The presented system of automated modeling makes it easier for the customer to control the quality of design solutions, to reasonably assign designs to layers of reinforcement, to quickly make comparisons of calculations of different designs for the optimal use of allocated funds. Prospects for further improvement of the program should be the results of theoretical and experimental studies on filling the databases, which are used as information support for automated design of road structures. Keywords: CREDO RADON UA, road, computer-aided design, repair project, road pavement, strengthening, construction, rigid pavement, elasticity module, a transport stream, calculation method, information support, dynamic or static loading.

scholarly journals Bond Behaviour of Near-Surface Mounted Strips in RC Beams—Experimental Investigation and Numerical Simulations

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4362
Author(s):  
Renata Kotynia ◽  
Hussien Abdel Baky ◽  
Kenneth W. Neale
Keyword(s):  
Concrete Strength ◽  
Element Model ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Experimental Program ◽  
Fe Model ◽  
Bond Behaviour ◽  
Near Surface ◽  
Cfrp Laminates ◽  
Near Surface Mounted

This paper presents an investigation of the bond mechanism between carbon fibre reinforced polymer (CFRP) laminates, concrete and steel in the near-surface mounted (NSM) CFRP-strengthened reinforced concrete (RC) beam-bond tests. The experimental program consisting of thirty modified concrete beams flexurally strengthened with NSM CFRP strips was published in. The effects of five parameters and their interactions on the ultimate load carrying capacities and the associated bond mechanisms of the beams are investigated in this paper with consideration of the following investigated parameters: beam span, beam depth, longitudinal tensile steel reinforcement ratio, the bond length of the CFRP strips and compressive concrete strength. The longitudinal steel reinforcement was cut at the beam mid-span in four beams to investigate a better assessment of the influence of the steel reinforcement ratio on the bond behaviour of CFRP to concrete bond behaviour. The numerical analysis implemented in this paper is based on a nonlinear micromechanical finite element model (FEM) that was used for investigation of the flexural behaviour of NSM CFRP-strengthened members. The 3D model based on advanced CFRP to concrete bond responses was introduced to modelling of tested specimens. The FEM procedure presents the orthotropic behaviour of the CFRP strips and the bond response between the CFRP and concrete. Comparison of the experimental and numerical results revealed an excellent agreement that confirms the suitability of the proposed FE model.

scholarly journals Experimental and Numerical Investigation on the Perforation Resistance of Double-Layered Metal Shield under High-Velocity Impact of Armor-Piercing Projectiles

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 626
Author(s):  
Riccardo Scazzosi ◽  
Marco Giglio ◽  
Andrea Manes
Keyword(s):  
High Strength Steel ◽  
Steel Plate ◽  
Experimental Studies ◽  
Practical Interest ◽  
High Strength ◽  
Experimental Tests ◽  
Element Model ◽  
Transportation Systems ◽  
Metal Shield ◽  
Softening Parameter

In the case of protection of transportation systems, the optimization of the shield is of practical interest to reduce the weight of such components and thus increase the payload or reduce the fuel consumption. As far as metal shields are concerned, some investigations based on numerical simulations showed that a multi-layered configuration made of layers of different metals could be a promising solution to reduce the weight of the shield. However, only a few experimental studies on this subject are available. The aim of this study is therefore to discuss whether or not a monolithic shield can be substituted by a double-layered configuration manufactured from two different metals and if such a configuration can guarantee the same perforation resistance at a lower weight. In order to answer this question, the performance of a ballistic shield constituted of a layer of high-strength steel and a layer of an aluminum alloy impacted by an armor piercing projectile was investigated in experimental tests. Furthermore, an axisymmetric finite element model was developed. The effect of the strain rate hardening parameter C and the thermal softening parameter m of the Johnson–Cook constitutive model was investigated. The numerical model was used to understand the perforation process and the energy dissipation mechanism inside the target. It was found that if the high-strength steel plate is used as a front layer, the specific ballistic energy increases by 54% with respect to the monolithic high-strength steel plate. On the other hand, the specific ballistic energy decreases if the aluminum plate is used as the front layer.

Reverse Modeling and Topological Optimization for Lightweight Design of Automobile Wheel Hubs with Hollow Ribs

2019 ◽  
Vol 17 (09) ◽  
pp. 1950064
Author(s):  
P. F. Xu ◽  
S. Y. Duan ◽  
F. Wang
Keyword(s):  
Finite Element ◽  
Lightweight Design ◽  
Element Model ◽  
Optimization Method ◽  
Modeling Technique ◽  
Topological Optimization ◽  
Time Interval ◽  
Braking Performance ◽  
Existing Structures ◽  
Physical Conditions

Lightweight of wheel hubs is the linchpin for reducing the unsprung mass and improving the vehicle dynamic and braking performance of vehicles, thus, sustaining stability and comfortability. Current experience-based lightweight designs of wheel hubs have been argued to render uneven distribution of materials. This work develops a novel method to combine the reverse modeling technique with the topological optimization method to derive lightweight wheel hubs based on the principles of mechanics. A reverse modeling technique is first adopted to scan and reproduce the prototype 3D geometry of the wheel hub with solid ribs. The finite element method (FEM) is then applied to perform stress analysis to identify the maximum stress and its location of wheel hub under variable potential physical conditions. The finite element model is then divided into optimization region and nonoptimized region: the former is the interior portion of spoke and the latter is the outer surface of the spoke. A topology optimization is then conducted to remove the optimization region which is interior material of the spokes. The hollow wheel hub is then reconstructed with constant wall thickness about 5[Formula: see text]mm via a reverse modeling technique. The results show that the reconstructed model can reduce the mass of 12.7% compared to the pre-optimized model. The present method of this paper can guarantee the optimal distribution of wheel hub material based on mechanics principle. It can be implemented automatically to shorten the time interval for optimal lightweight designs. It is especially preferable for many existing structures and components as it maintains the structural appearance of optimization object.

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