scholarly journals Calculation of the prestressing force in the design of reinforced concrete structures strengthened by means of external reinforcement with prestress

2020 ◽  
Vol 17 (5) ◽  
pp. 59-65
Author(s):  
A. D. Denisova ◽  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
General Information ◽  
Steel Plates ◽  
Fiber Reinforced Polymers ◽  
Reinforced Concrete Structures ◽  
Concrete Element ◽  
Reinforced Polymers ◽  
Prestressing Force ◽  
External Reinforcement

The article provides general information on external reinforcement systems with the use of fiber reinforced polymers (FRP) with prestressing for strengthening of reinforced concrete structures. A classification of existing systems is submitted. The author has performed calculation of the prestressing force taking into account all prestress losses for an externally strengthened reinforced concrete element. Herewith, there were applied steel plates, FRP laminates, based on the methodology set out in SP 63.13330, taking into account the properties of each of the prestressed materials and different levels of initial prestressing.

scholarly journals Adhesion characteristics of geopolymer mortar to concrete and rebars

2019 ◽  
Vol 258 ◽  
pp. 01012 ◽  
Author(s):  
Sanjay Pareek ◽  
Hiroo Kashima ◽  
Ippei Maruyama ◽  
Yoshikazu Araki
Keyword(s):  
Reinforced Concrete ◽  
Building Materials ◽  
Concrete Structures ◽  
Acid Resistance ◽  
Steel Plates ◽  
Alkali Concentration ◽  
Reinforced Concrete Structures ◽  
Interfacial Zone ◽  
Adhesion Properties ◽  
Repair Materials

In recent years, geopolymers have gained a wide attention as highly ecological-friendly building materials, having a capability to cut down 70% of CO2 emissions in comparison to the ordinary cement concrete. In this study, geopolymer mortars are proposed as repair materials for reinforced concrete structures, due to their superior acid resistance, heat resistance and high strength in comparison to the existing repair materials. The objective of this study is to investigate the adhesion properties of geopolymer mortars to concrete substrates with different surface treatments, steel plates and rebars. As a result, the geopolymer mortars are found to have excellent adhesion properties to dry concrete substrates, steel plates and rebars. Concrete substrates treated with grinder, further enhanced the adhesion properties of geopolymer mortars. On the other hand, poor adhesion of geopolymer mortars to wet concrete substrates was observed due to the presence of water on the interfacial zone, which decreased the alkali concentration of the geopolymer, resulting in lower adhesion strength. In general, geopolymer mortars are found to have suitable adhesion properties to the concrete substrates, steel plates and rebars and can be applied as repair materials for reinforced concrete structures.

scholarly journals Reinforced concrete structures strengthened with CFRP (ACI x FIB) - Recommendations for bending design criteria

2022 ◽  
Vol 15 (2) ◽  
Author(s):  
Igor Del Gaudio Orlando ◽  
Túlio Nogueira Bittencourt ◽  
Leila Cristina Meneghetti
Keyword(s):  
Reinforced Concrete ◽  
Limit State ◽  
Concrete Structures ◽  
Experimental Tests ◽  
Fiber Reinforced Polymers ◽  
Design Criteria ◽  
Ultimate Limit State ◽  
Reinforced Concrete Structures ◽  
Carbon Fiber Reinforced Polymers ◽  
Model Code

abstract: This work deals with the evaluation of the design criteria and security check (Ultimate Limit State - ULS) of the American (ACI-440.2R, 2017) and European (FIB Model Code, 2010) standards of reinforced concrete structures strengthened with Carbon Fiber Reinforced Polymers (CFRP), by the technique of Externally Bonded Reinforcement (EBR). It is intended to evaluate if, for a given database of 64 experimental tests of beams and slabs, the obtained results respect the safety conditions according to the mentioned standards, to increase the efficiency of this reinforcement technique and to lead to the establishment of regulatory design criteria in Brazil. Results show a conservative match among experimental and theoretical values calculated according to the two guidelines and it is concluded that a future regulation in Brazil on this subject should be based on the FIB Model Code.

scholarly journals An integrated approach to the use of composite materials for the restoration of reinforced concrete structures

2019 ◽  
Vol 135 ◽  
pp. 03068 ◽  
Author(s):  
Vladimir Rimshin ◽  
Pavel Truntov
Keyword(s):  
Reinforced Concrete ◽  
Composite Materials ◽  
Bearing Capacity ◽  
Concrete Structures ◽  
Integrated Approach ◽  
Reinforced Concrete Structures ◽  
Technical Inspection ◽  
Concrete Layer ◽  
External Reinforcement ◽  
Calculation Results

The article presents the results of a technical inspection of the state of the structures of the object. To conduct the study, horizontal structures of the sludge pool that were exposed to the carbonization reaction were taken for the objects under investigation. Defects and damages of the considered structures revealed during visual inspection are described. The degree of carbonization of reinforced concrete structures was determined by the phenolphthalein sample method. According to the results of the technical inspection, a verification calculation of the beam was carried out in order to determine its bearing capacity for assessing the suitability for further operation after restoration and strengthening. The calculation was performed using software. Based on the calculation results, data on the bearing capacity of the beam reinforced with composite materials were determined. The option of restoring and strengthening the beam using external reinforcement based on carbon fibers FibArm 230/150 is presented. The restoration was carried out taking into account the carbonized concrete layer. Based on the results of the study, an assessment is given of the application of an integrated approach to the restoration and strengthening of structures with composite materials, taking into account the carbonized concrete layer.

scholarly journals Prepared experimental study for durability verification of FRP reinforced concrete members

2021 ◽  
Vol 1209 (1) ◽  
pp. 012055
Author(s):  
S Blaho ◽  
K Gajdošová
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Concrete Structures ◽  
High Strength ◽  
Bending Test ◽  
Reinforced Concrete Structures ◽  
Reinforced Polymers ◽  
Concrete Members ◽  
Four Point Bending

Abstract Major advantage of fibre reinforced polymers (FRPs) is their high strength and low weight to strength ratio. These are also the main reasons for a choice for this material in the process of design of reinforced concrete structures. Since there is no corrosion of FRP, this reinforcement could be strongly recommended for concrete reinforcement in aggressive environment. Till today there is no sufficient knowledge of long-term behaviour of FRP-reinforced concrete structures. Design codes give low utilization capacity of FRP materials and are not supposed to be correct according to the real behaviour in a few experiments of last decades. Reduction factors limit the mechanical properties in the range from 0.95 for CFRP to 0.5 for GFRP. In the paper there is presented a prepared and today realized long-term experimental study based on four point bending test on simply supported concrete beams reinforced with GFRP reinforcement.

scholarly journals Development of Bonded/Riveted Steel Anchorages of Prestressed CFRP Strips for Concrete Strengthening

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2217
Author(s):  
Bartosz Piątek ◽  
Tomasz Siwowski ◽  
Jerzy Michałowski ◽  
Stanisław Błażewicz
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Concrete Surface ◽  
Epoxy Adhesive ◽  
Full Scale ◽  
Steel Plates ◽  
Tensile Failure ◽  
Small Scale ◽  
Reinforced Concrete Structures ◽  
Flexural Strengthening

CFRP (carbon fiber reinforced polymer) strips are currently often used to strengthen reinforced concrete structures in flexure. In order to ensure effective strengthening, proper connection between FRP material and concrete structure is needed. CFRP strips can be applied passively (only by bonding to the concrete surface) or actively (by prestressing before bonding). In the case of passive strengthening, CFRP strips connecting by bonding to the surface along the strengthened element are usually sufficient. However, active (prestressing) CFRP strips should be additionally anchored at their ends. Anchoring of unidirectional CFRP strips to the reinforced concrete is difficult because of their weak properties in transverse directions. The paper presents a development of mechanical steel anchorages used in an active CFRP flexural strengthening system for reinforced concrete structures. The anchorages were made of steel plates connected to CFRP strips with steel rivets and epoxy adhesive. They were developed within series of tests on specimens from small-scale to full-scale tested in an axial tensile scheme. The paper describes successive modifications of the anchorages as well as the results of full-scale tests. The final version of the anchorage developed during the research had a tensile failure force of 185 kN, which is sufficient value for CFRP strengthening purposes.

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