scholarly journals Influence of Embedded through Section Connectors on the Behavior of a New Strengthening Technique for Concrete Structures

2016 ◽  
Vol 711 ◽  
pp. 996-1003
Author(s):  
Tiago Valente ◽  
Davide Colarusso ◽  
Marisa Pecce ◽  
Francesca Ceroni ◽  
Joaquim Barros
Keyword(s):  
Structural Response ◽  
High Strength ◽  
Thin Layers ◽  
Experimental Program ◽  
Infill Walls ◽  
Rc Structures ◽  
Strength And Stiffness ◽  
Ductile Behavior ◽  
Strengthening Technique ◽  
Rc Framed Structures

An innovative technique is being developed for the structural rehabilitation of Reinforced Concrete (RC) structures. In particular, the infill walls of RC framed structures are often identified as non-structural elements, but currently are considered with an important role in the structural behavior because they participate to the in-plane strength and stiffness of the frames and they can give very dangerous crashes out-of-plane. In this paper a strengthening technique aimed to repair infill walls is proposed. It is based on the application of outer thin layers of ultra-high ductile fiber reinforced mortar (UHDFRM) applied according to the shotcrete technique, including the use of embedded through section (ETS) connectors. This strengthening system can exhibit a high strength and ductile behavior, increase the load carrying capacity, energy absorption and dissipation capacities, and ultimately improve the structural response of RC structures when submitted to loading conditions typical of seismic events. An experimental program was outlined in order to assess the contribution of different types of ETS connectors on the behavior of the strengthening system. The experimental program comprised the performance of push-out tests on samples representative of the structural strengthening solution, namely low strength concrete samples. The experimental results are discussed in detail in order to highlight the effectiveness of the various types of ETS connectors tested.

scholarly journals TEXTILE REINFORCED MORTAR BASED FLEXURAL STRENGTHENING OF REINFORCED CONCRETE BEAMS

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Muhammad Imran Rafiq ◽  
Ameer Baiee
Keyword(s):  
Reinforced Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Strengthening Technique ◽  
Textile Reinforced Mortar

Strengthening of reinforced concrete (RC) structures is often necessary due to the change of using or to enhance the strength of deteriorated existing RC structures attributed to aging and environmental effects. Interfacial bond between the existing RC member and the strengthening layer is known to be the main factor for any successful strengthening technique. This study investigates the efficiency of utilizing high strength cementitious connectors in preventing the debonding of textile reinforced mortar (TRM) strengthening layer from substrate concrete of RC beams. An experimental program is developed to investigate the effect of strength of mortars and the distribution of cementitious connectors on the behavior of the strengthened beams. TRM comprising eight and sixteen textile basalt fiber layers were utilized in these experiments. The results demonstrate the effectiveness of cementitious connectors on the failure mode of strengthened beams by means of controlling the debonding of TRM. The increase in cracking and ultimate loads is demonstrated due to the strengthening of RC beams using TRM.

Structural Response of Sandwich Beams with Different Facing Materials Subjected to Bending

2017 ◽  
Vol 21 ◽  
pp. 294-300
Author(s):  
Iuliana Dupir ◽  
Nicolae Ţăranu ◽  
Cristina Vlădoiu ◽  
Dragoş Ungureanu ◽  
Vlad Lupăşteanu
Keyword(s):  
Numerical Analysis ◽  
Structural Response ◽  
High Strength ◽  
Specific Weight ◽  
Foam Core ◽  
Sandwich Beams ◽  
Stress Distributions ◽  
Structural Functions ◽  
Strength And Stiffness ◽  
Lightweight Core

Sandwich elements with structural functions are widely used in engineering applications, offering outstanding advantages, such as high strength and stiffness compared to its low specific weight. The sandwich elements consist in two stiff and thin faces, separated by a thick and lightweight core. A numerical analysis is performed in this paper, in order to evaluate the flexural structural response of sandwich beams with foam core and various facing materials. It has been noticed that the deflections decrease when the stiffness of the facings increase. The results are represented in terms of maximum deflections and direct stress distributions.

Solid Freeform Fabrication of Composites by Direct Deposition and by In Situ Mineralization

1998 ◽  
Vol 542 ◽  
Author(s):  
Paul Calvert ◽  
Jiong Peng ◽  
Chad Souvignier
Keyword(s):  
Solid Freeform Fabrication ◽  
Fiber Type ◽  
High Strength ◽  
Thin Layers ◽  
Gelling Agent ◽  
Freeform Fabrication ◽  
Silica Hybrids ◽  
Strength And Stiffness ◽  
Packing Effects

AbstractFreeform fabrication methods build materials by the repetitive addition of thin layers. This approach can be applied to build parts from epoxy resin which is modified with a gelling agent to solidify the material until curing occurs. High strength and stiffness parts can be obtained through fiber reinforcement but the fiber content is limited by packing effects. We have found that a combination of two types of fibers can be used to achieve higher strength and stiffness than can be obtained from a single fiber type.An alternative route to reinforcement is to form the reinforcing phase after the material is deposited by an in situ reaction. This approach has been applied to the use of freeform fabrication to make bars of mineralized gel and of methacrylate-silica hybrids. Good mechanical properties can be attained in each case, with up to 50 vol.% inorganic phase and bend strengths in the range from 50-100 MPa.

scholarly journals Fiber Reinforced Concrete for repairing and strengthening RC structures: some recent advancements

2018 ◽  
Vol 199 ◽  
pp. 01004
Author(s):  
Giovanni A. Plizzari
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Structural Response ◽  
Thin Layers ◽  
Fiber Reinforced Concrete ◽  
Seismic Retrofitting ◽  
Structural Safety ◽  
Fibre Reinforced Concrete ◽  
Seismic Behaviour ◽  
Rc Structures

Enhancement of seismic behaviour of existing structures, both masonry or reinforced concrete, is a key issue for future technical activities in many Western Countries, since construction of new buildings has decreased in favour of an increased attention to the structural rehabilitation and re-use of existing buildings. The development of innovative repairing, strengthening, and retrofitting techniques is, therefore, a crucial topic to improve the structural safety of existent constructions. Fibre Reinforced Concrete (FRC) may now be particularly efficient in these cases, due to the high toughness provided by fibres that may reduce or avoid the use of conventional reinforcement.This paper presents the results of two experimental research studies carried out at the University of Brescia, concerning the use of FRC as the principal reinforcing material. The first study aims at assessing the structural response, under cyclic horizontal loads, of a full scale (1:1) Unreinforced Masonry (URM) building retrofitted with Steel Fibre Reinforced Mortar (SFRM) as external plaster. The second study concerns the seismic retrofitting of a scaled (1:4) reinforced concrete bridge pier by means of a High Performance Fibre Reinforced Concrete (HPFRC) jacketing. In both cases, repair material is applied in thin layers, due to the high mechanical properties compared to those of the respective substrates, with the addition of a limited amount of traditional reinforcement, placed only on the most stressed sections.

Flexural and Shear Strength of Granite Reinforced by Metal Rods

2010 ◽  
Vol 133-134 ◽  
pp. 417-422 ◽  
Author(s):  
Sung Gul Hong ◽  
Woo Young Lim
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
High Strength Concrete ◽  
High Strength ◽  
Stone Masonry ◽  
Experimental Program ◽  
Notched Specimens ◽  
Dowel Action ◽  
Final Failure ◽  
Ductile Behavior

This paper investigates feasibility of reinforcement method for fractured granite of slab type and beam members used as components of old stone masonry pagodas. Investigation of the effect of reinforcement to flexural and shear strength is performed using the concept for the high strength concrete since the mechanical properties of granite are similar to properties of high strength of concrete. In this experimental program two types of notched specimens are intended for failures with shear and flexural cracks. Intended fractured specimens are reinforced by metal rods, so called pinning method. The rods are inserted in holes and bonded with inorganic cement. The metal rods are supposed to transfer forces by tensile resistance in flexure and dowel action in shear. Increase in shear and flexural capacities and ductile behavior after sudden yielding of the metal rods are observed. The final failure cracks in reinforced specimens occurred different from interfaces along the original cracks. Locations of metal rods, their numbers, and construction of anchored rod are main variables to be examined for guidelines for reinforcement methods.

Experimental Evaluation of Lightweight AAC Masonry Wall Prisms with Ferrocement Layers in Compression and Flexure

2012 ◽  
Vol 166-169 ◽  
pp. 1730-1735 ◽  
Author(s):  
Mohamed Abdel-Mooty ◽  
Ahmed Hendam ◽  
Ezzat Fahmy ◽  
Mohamed Abou Zeid ◽  
Medhat Haroun
Keyword(s):  
Masonry Wall ◽  
Wire Mesh ◽  
Experimental Program ◽  
Design Parameters ◽  
Shear Connectors ◽  
Mortar Strength ◽  
Wall Strength ◽  
Out Of Plane ◽  
Strength And Stiffness ◽  
Strengthening Technique

An experimental program is designed to evaluate the performance of lightweight autoclaved aerated concrete masonry wall strengthened using ferrocement layers, in a sandwich structure, under in-plane compression and out-of-plane bending. The 25 mm thick ferrocement mortar is reinforced with steel welded wire mesh of 1 mm diameters at 15 mm spacing. Different types of shear connectors are used to evaluate their effect on failure loads. The effect of different design parameters on the wall strength are considered including wall thickness, mortar strength, and type and distribution of shear connectors. A total of 20 prisms are tested in compression and 5 prisms are tested under bending. The proposed ferrocement strengthening technique is easy to apply on existing wall system and results in significant strength and stiffness enhancement of the tested wall specimens.

scholarly journals Flexural Performance of RC Beams Strengthened with Externally-Side Bonded Reinforcement (E-SBR) Technique Using CFRP Composites

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2809
Author(s):  
Md. Akter Hosen ◽  
Fadi Althoey ◽  
Mohd Zamin Jumaat ◽  
U. Johnson Alengaram ◽  
N. H. Ramli Sulong
Keyword(s):  
Absorption Capacity ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Functional Changes ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Flexural Performance ◽  
Design Loads ◽  
Predicted Values

Reinforced concrete (RC) structures necessitate strengthening for various reasons. These include ageing, deterioration of materials due to environmental effects, trivial initial design and construction, deficiency of maintenance, the advancement of design loads, and functional changes. RC structures strengthening with the carbon fiber reinforced polymer (CFRP) has been used extensively during the last few decades due to their advantages over steel reinforcement. This paper introduces an experimental approach for flexural strengthening of RC beams with Externally-Side Bonded Reinforcement (E-SBR) using CFRP fabrics. The experimental program comprises eight full-scale RC beams tested under a four-point flexural test up to failure. The parameters investigated include the main tensile steel reinforcing ratio and the width of CFRP fabrics. The experimental outcomes show that an increase in the tensile reinforcement ratio and width of the CFRP laminates enhanced the first cracking and ultimate load-bearing capacities of the strengthened beams up to 141 and 174%, respectively, compared to the control beam. The strengthened RC beams exhibited superior energy absorption capacity, stiffness, and ductile response. The comparison of the experimental and predicted values shows that these two are in good agreement.

scholarly journals Materials for Automotive Lightweighting

2019 ◽  
Vol 49 (1) ◽  
pp. 327-359 ◽  
Author(s):  
Alan Taub ◽  
Emmanuel De Moor ◽  
Alan Luo ◽  
David K. Matlock ◽  
John G. Speer ◽  
...  
Keyword(s):  
Galvanic Corrosion ◽  
Low Carbon Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
New Materials ◽  
Specific Strength ◽  
Advanced High Strength Steels ◽  
Strength And Stiffness ◽  
The Cost

Reducing the weight of automobiles is a major contributor to increased fuel economy. The baseline materials for vehicle construction, low-carbon steel and cast iron, are being replaced by materials with higher specific strength and stiffness: advanced high-strength steels, aluminum, magnesium, and polymer composites. The key challenge is to reduce the cost of manufacturing structures with these new materials. Maximizing the weight reduction requires optimized designs utilizing multimaterials in various forms. This use of mixed materials presents additional challenges in joining and preventing galvanic corrosion.

scholarly journals Experimental Study on the Torsional Behaviour of Prestressed HSC Hollow Beams

2020 ◽  
Vol 10 (2) ◽  
pp. 642 ◽  
Author(s):  
Luís Bernardo ◽  
Sérgio Lopes ◽  
Mafalda Teixeira
Keyword(s):  
Experimental Study ◽  
High Strength Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Experimental Program ◽  
Pure Torsion ◽  
Strength Concrete ◽  
Hollow Beams

This article describes an experimental program developed to study the influence of longitudinal prestress on the behaviour of high-strength concrete hollow beams under pure torsion. The pre-cracking, the post-cracking and the ultimate behaviour are analysed. Three tests were carried out on large hollow high-strength concrete beams with similar concrete strength. The variable studied was the level of longitudinal uniform prestress. Some important conclusions on different aspects of the beams’ behaviour are presented. These conclusions, considered important for the design of box bridges, include the influence of the level of prestress in the cracking and ultimate behaviour.

scholarly journals Prediction of the Fundamental Period of Infilled RC Frame Structures Using Artificial Neural Networks

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Panagiotis G. Asteris ◽  
Athanasios K. Tsaris ◽  
Liborio Cavaleri ◽  
Constantinos C. Repapis ◽  
Angeliki Papalou ◽  
...  
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Fundamental Period ◽  
Critical Parameters ◽  
Frame Structures ◽  
Rc Frame ◽  
Infill Walls ◽  
Rc Structures ◽  
Artificial Neural ◽  
Rc Frame Structures

The fundamental period is one of the most critical parameters for the seismic design of structures. There are several literature approaches for its estimation which often conflict with each other, making their use questionable. Furthermore, the majority of these approaches do not take into account the presence of infill walls into the structure despite the fact that infill walls increase the stiffness and mass of structure leading to significant changes in the fundamental period. In the present paper, artificial neural networks (ANNs) are used to predict the fundamental period of infilled reinforced concrete (RC) structures. For the training and the validation of the ANN, a large data set is used based on a detailed investigation of the parameters that affect the fundamental period of RC structures. The comparison of the predicted values with analytical ones indicates the potential of using ANNs for the prediction of the fundamental period of infilled RC frame structures taking into account the crucial parameters that influence its value.

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