scholarly journals Possibilities of Increasing Effectiveness of RC Structure Strengthening with FRP Materials

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1387
Author(s):  
Wit Derkowski ◽  
Rafał Walczak
Keyword(s):  
Composite Laminates ◽  
Civil Engineering ◽  
Adhesive Layer ◽  
Epoxy Adhesive ◽  
Building Structures ◽  
Complex Behaviour ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

Modern composite materials based on non-metallic continuous fibres are increasingly used in civil engineering to strengthen building structures. In the strengthening of reinforced concrete (RC) structures, the utilisation of externally bonded fibre-reinforced polymer (FRP) composites is only up to 35% because of the pilling-off failure mechanism. This problem can be solved using pre-tensioned composite laminates. Due to more complex behaviour, the strengthening of structures by means of prestressing technology needs a careful design approach and a full understanding of the behaviour of both the materials and elements. The advantages and risks of the presented technology, which may determine the success of the entire project, will be highlighted in the paper. The possibility of using a flexible adhesive layer in carbon fibre reinforced polymer (CFRP) strengthening applications for flexural strengthening of RC elements, as an innovative solution in civil engineering, will also be presented. Parallel introduction of the flexible adhesive layer (made of polyurethane masses) and a traditional epoxy adhesive layer in one strengthening system was investigated in the laboratory tests. This solution was used for the repair and protection of a previously damaged RC beam against brittle failure.

Experimental research on hybrid anchorages of prestressed composite strips for structural strengthening

2021 ◽  
pp. 002199832110203
Author(s):  
Bartosz Piątek ◽  
Tomasz Siwowski ◽  
Jerzy Michałowski ◽  
Stanisław Błażewicz
Keyword(s):  
High Strength ◽  
Epoxy Adhesive ◽  
Steel Plates ◽  
Flexural Strengthening ◽  
Reinforced Polymer ◽  
Axial Tensile ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Cfrp Strip ◽  
Full Scale Tests

The prestressed unidirectional carbon fibre reinforced polymer (CFRP) strips are currently often used for flexural strengthening of concrete structures. To ensure reliable strengthening, strips have to be anchored at their ends to the surface. However, anchoring of unidirectional CFRP strips is difficult because of their weak transversal mechanical properties. Although several CFRP strip anchorage approaches have been developed to date, only very few were applied on-site. The paper presents the development of hybrid bonded/bolted anchorages of CFRP strips used in a novel prestressing system. The anchorages are made of thin steel plates, clamped with the high-strength friction grip (HSFG) bolts and epoxy adhesive, to fix the CFRP strips. The paper describes the results of full-scale tests carried out on a series of axial tensile specimens. The developed anchorage has an ultimate tensile strength of about 200 kN, i.e. 70% of the ultra-high CFRP strips’ strength, which is sufficient for strengthening purposes. After a series of tests in the laboratory, the anchorages have been implemented on-site and an example is presented in the paper.

Influence of Ply Stacking Sequences on the Impact Response of Carbon Fibre Reinforced Polymer Composite Laminates

2019 ◽  
Author(s):  
Kristian Gjerrestad Andersen ◽  
Gbanaibolou Jombo ◽  
Sikiru Oluwarotimi Ismail ◽  
Segun Adeyemi ◽  
Rajini N ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
Polymer Composite ◽  
Composite Laminates ◽  
Impact Response ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
The Impact

Durability of coral-reef-sand concrete beams reinforced with basalt fibre-reinforced polymer bars in seawater

2021 ◽  
pp. 136943322098166
Author(s):  
Wang Xin ◽  
Shi Jianzhe ◽  
Ding Lining ◽  
Jin Yundong ◽  
Wu Zhishen
Keyword(s):  
Coral Reef ◽  
Marine Environment ◽  
Failure Modes ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Initial Stiffness ◽  
Basalt Fibre ◽  
Rc Structures ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer

A combination of coral reef sand (CRS) concrete and fibre-reinforced polymer (FRP) bars provides an effective solution to the durability deficiency in conventional RC structures. This study experimentally investigates the durability of CRS concrete beams reinforced with basalt FRP (BFRP) bars in a simulated marine environment. Flexural tests are conducted on a total of fourteen CRS concrete beams aged in a cyclic wet-dry saline solution at temperatures of 25, 40 and 55°C. The variables comprise the types of reinforcement (steel and BFRP), the aging duration and the temperature. The failure modes, capacities, deflections and crack development of the beams are analysed and discussed. The results indicate that the ultimate load of the beams exhibits no degradation after aging, whereas the failure mode of the BFRP-CRS concrete beams transition from flexure to shear, which is caused by the degradation in the mechanical properties of the stirrups. The aged BFRP-CRS concrete beams show a substantial increase of over 70% in their initial stiffness compared with the control beams (beams without aging) and a substantial decrease in their crack width after aging due to the prolonged maturation of the concrete. Furthermore, a formula for calculating the shear capacity in the existing code is modified by a partial factor equal to 2, which can predict the capacity of a CRS concrete beam reinforced with BFRP bars in a marine environment.

Effect of nanofiller on fibre laser drilling quality of carbon fibre reinforced polymer composite laminates

2018 ◽  
Vol 233 (4) ◽  
pp. 857-870
Author(s):  
Dhiraj Kumar ◽  
Kalyan Kumar Singh
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Fibre ◽  
Polymer Matrix ◽  
Composite Laminates ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Multi Walled Carbon Nanotubes ◽  
Fibre Reinforced Polymer ◽  
Walled Carbon Nanotubes

Laser machining of carbon fibre reinforced polymer composites is a challenging task due to a significant difference between physical and thermal properties of the constituent materials, i.e. polymer matrix and carbon fibres. This results in extended heat-affected zone (HAZ), taper kerf and poor surface finishing. This paper focuses on an investigation, attempting to minimise the divergence in the decomposition temperature of carbon fibres and epoxy resin by adding multi-walled carbon nanotubes in polymer matrix as a secondary reinforcement. High thermal conductivity of multi-walled carbon nanotubes increases the thermal diffusivity of polymer matrix, which in turn reduces the matrix recession. In addition, laser power and scan speed was also considered as an input parameter and their influence on output responses such as HAZ, taper angle and surface roughness has been studied. To analyse the effect of multi-walled carbon nanotubes on the resultant thermal damage, an innovative technique, i.e. scanning acoustic microscopy was used. This technique provides a ply-by-ply damage analysis. C-scans of the top and bottom surface of the machined holes in the composite were also carried out. Further, micrographs of the holes were taken to analyse the quality of the holes using field-emission scanning electron microscope. The obtained results indicated that HAZ, taper angle and surface roughness of holes decreased by ∼30%, ∼47% and ∼43%, respectively, with 1.5 wt% multi-walled carbon nanotubes doped carbon fibre reinforced polymer laminates, when compared with the results obtained from experiments with neat carbon fibre reinforced polymer composite laminates.

scholarly journals An experimental study on flexural strengthening of RC beams using CFRP sheets

2018 ◽  
Vol 7 (4) ◽  
pp. 2075 ◽  
Author(s):  
Yasmin Murad
Keyword(s):  
Flexural Strength ◽  
Orientation Angle ◽  
Longitudinal Axis ◽  
Flexural Behavior ◽  
Experimental Program ◽  
Rc Beams ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Cfrp Sheets ◽  
Reinforced Polymer

 The use of carbon fiber reinforced polymer (CFRP) sheets is becoming a widely accepted solution for strengthening and repairing rein-forced concrete (RC) structures. To date, the behavior of RC beams, strengthened with 60˚ and 45˚ inclined CFRP sheets, has not clearly explained. An experimental program is proposed in this paper to investigate the flexural behavior of RC beams strengthened with CFRP sheets. CFRP sheets were epoxy bonded to the tension face to enhance the flexural strength of beams inducing different orientation angles of 0˚, 45˚, 60˚ and 90˚ with the beam longitudinal axis. The study shows that strengthening RC beams with CFRP sheets is highly influenced by the orientation angle of the sheets. The orientation angle plays a key role in changing the crack pattern and hence the failure mode. The influence of CFRP sheets was adequate on increasing the flexural strength of RC beams but the ductility of the beams was reduced. The best performance was obtained when strengthening RC beam obliquely using 45˚ inclined CFRP sheets where the specimen experienced additional deflection and strength of 56% and 12% respectively and the reduction in its ductility was the least. It is recom-mended to strengthen RC beams, which are weak in flexure, using 45˚ inclined CFRP sheets.  

Flexural strengthening of precast reinforced concrete bridge girders using bonded carbon fibre reinforced polymer strips or external post-tensioning

2004 ◽  
Vol 31 (3) ◽  
pp. 499-512 ◽  
Author(s):  
Ezzeldin Y Sayed-Ahmed ◽  
Amr H Riad ◽  
Nigel G Shrive
Keyword(s):  
Reinforced Concrete ◽  
Bridge Girders ◽  
Concrete Bridge ◽  
Flexural Strengthening ◽  
Reinforced Concrete Bridge ◽  
Concrete Girders ◽  
Reinforced Polymer ◽  
External Prestressing ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer

Strengthening of reinforced concrete bridge girders has become a major concern. Many reinforced concrete highway bridges were constructed in Canada using precast reinforced concrete girders, and currently many of them need rehabilitation. Thus, two techniques for flexural strengthening of precast reinforced concrete bridge girders (HC-type) were investigated experimentally. The first technique involved bonding carbon fibre reinforced polymer (CFRP) strips to the soffits of the girders. The second technique was classical external post-tensioning with steel bars. A simple, yet innovative method was developed for applying the external prestressing to these girders. The experimental investigation was performed on full-scale girders from a dismantled bridge in Alberta (Canada). Outcomes of the experimental investigation led to the conclusion that classical methods of flexural strengthening (e.g., external prestressing) should not be completely disregarded. Also, an additional mode of failure needs to be added to currently available prediction models for estimating the gain in flexural strength of reinforced concrete girders retrofitted using bonded CFRP strips.Key words: bridges, CFRP, flexure strengthening, precast girders, post tension, prestressing, rehabilitation.

scholarly journals Evaluation of Strength Characteristics of Concrete by Glass Fibre Reinforced Polymer (GFRP) And Carbon Fibre Reinforced Polymer (CFRP) Wrapping

2021 ◽  
Vol 9 (VIII) ◽  
pp. 831-836
Author(s):  
Shalini G V
Keyword(s):  
Construction Projects ◽  
Construction Material ◽  
Rc Structures ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Operational Life ◽  
Compressive Loads ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced

The construction material mainly reinforced concrete is being used extensively for various type of construction projects. However, deterioration of RC structures is recognized as a major problem worldwide. Extension of the structures’ life is an inevitable need for a healthy planet. Any deficiency caused to the members of the structure may affect the life of structure. Therefore, it is important that the members should provide adequate strength (for which it is designed) throughout its operational life. But, it has been observed that due to alteration in purpose of use of structure (very common in mega cities), improper design and deficiency caused due to earthquake, blast and impacts in structural members and as a result in the members structure can possibly be subjected to loads which have higher magnitude compared to its design loads. This study is based on experimental investigation to assess the behavior of CFRP & GFRP wrapped concrete under compressive loads. For this purpose, M30 grade concrete specimens have been casted and wrapped it with Glass and Carbon FRP and its strength against compressive loads have been found.

Sign in / Sign up

Export Citation Format

Share Document