Tomas Skuturna

Bio: Tomas Skuturna is an academic researcher from Vilnius Gediminas Technical University. The author has contributed to research in topics: Deflection (engineering) & Fibre-reinforced plastic. The author has an hindex of 8, co-authored 13 publications receiving 186 citations.

Experimental study on the effect of anchorage systems on RC beams strengthened using FRP

Abstract: In the strengthening of reinforced concrete structures using fibre-reinforced plastic (FRP), the achievement of a strong bond between the FRP and the concrete is beneficial. However, studies have revealed that the bond is often unreliable under high loads, and a means of augmenting the anchorage of the FRP is required to strengthen its bonding with the concrete. In the present study, the effects of various methods for augmenting the FRP anchorage to strengthened concrete structures in the service and failure modes were investigated. This paper presents the results of the experimental investigation of thirty-two beams. The effects of using steel pins, steel clamps, and FRP wraps on the strength of the beams were examined, as well as those of the steel clamp area and the initial compression induced by the clamps. It was found that the strengthening effect and failure mode varied with the adopted FRP anchorage augmentation method. An analysis of the experimental results revealed that the most effective anchorage augmentation method was the use of steel clamps. The application of an initial compression by the clamps was also determined to be beneficial. The highest strength was achieved using a steel clamp of area 50 cm2 and an initial compression of 1 MPa.

Cracking and strength of reinforced concrete structures in flexure strengthened with carbon fibre laminates

Abstract: The article presents the analysis of the cracking moment and the strength of beams reinforced with external carbon fibre. Experimental research of beams strengthened in this way has been carried out. Three different methods of anchoring external reinforcement were applied to strengthen the beams. The influence of anchorage on the cracking moment and the strength of the beams has been defined. Design methods for defining the cracking moment and the strength have been presented. The design procedure for defining the cracking moment evaluates the curvilinear stress diagrams of concrete under tension and compression. The design procedure for defining the strength of the structures evaluates the stiffness of the contact between the carbon fibre and the concrete. The design results are provided. Comparative analysis of the experimental and the theoretical results has been performed.

Flexural capacity and stiffness of monolithic biaxial hollow slabs

Abstract: The article presents a research on flexural behaviour of hollow monolithic reinforced concrete slabs. It focuses on the results of experimental investigation into full-size hollow reinforced concrete slabs and analyses their flexural capacity and stiffness. The self-weight of the slabs directly depends on the shape and number of hollows. An increase in the hollowness of a slab significantly reduces the load caused by self-weight. This allows increasing the estimated length of the slab under the same payload. An increase in the amount of hollows of the slab changes the stiffness of the slab cross-section that has a direct impact on slab deflection. Considering the shape of the slab cross-section, theoretical calculations of the flexural capacity and deflection of experimental slabs were made. The design of a new type of slabs and variations in different parameters of the slab experience difficulties in conducting a large amount of experimental tests. Therefore, the initial analysis may apply to numerical simulation. The paper describes the principles of designing a numerical model. The calculations were made using DIANA software. The stiffness and flexural capacity of the hollow slabs were established employing numerical simulation compared to the results of experimental investigations. The findings indicate that numerical simulation can be applied for analysing the stress state of the examined structures.

Analysis of Deflections of Bridge Girders Strengthened by Carbon Fibre Reinforcement

Abstract: The paper deals with experimental and theoretical investigations in reinforced concrete structures strengthened with carbon fiber sheets. Four stages in the behavior of concrete structures strengthened with the carbon fiber reinforced polymer (CFRP) are distinguished. A method for calculating the deflections of such structures is presented. The design procedure for defining the strength of structures evaluates the stiffness of the contact between the carbon fiber and the concrete. Experimental investigations with different fastening methods of the CFRP to the concrete were performed. In experimental investigations, deflections of the strengthened members were examined. Results of the calculations of deflections for experimental beams according to the proposed method are presented. A comparison of experimental and theoretical deflections is presented in the paper.

Experimental study of flexural behaviour of RC beams strengthened by longitudinal and U-shaped basalt FRP sheet

Abstract: Fiber Reinforced Polymer (FRP) composite products such as Carbon FRP (CFRP) or Glass FRP (GFRP) have been intensively studied for strengthening reinforced concrete (RC) and masonry structures. It has been reported that FRP strengthening is effective to enhance the structural load-carrying capacity. Basalt FRP (BFRP) is a promising material for the application to structure strengthening with its advantages of low cost, corrosion resistant and sound mechanical property, but only limited studies of using Basalt FRP to externally strengthen RC beam are available in the literature. This study is to experimentally explore the effectiveness of application of Basalt FRP to strengthen RC beam under three-point bending test. The damage modes and structural response of unstrengthened and BFRP strengthened RC beams were recorded and identified. The effects of various BFRP wrapping schemes, U-jacket anchorage and epoxy adhesives on the flexural capacity of RC beams were analysed and discussed. In addition, the formulae used to predict the flexural behaviour of RC beam strengthened by other FRP composites (e.g. CFRP/GFRP) were evaluated for their applicability to Basalt FRP strengthening.

Reinforced concrete beams strengthened in flexure with near-surface mounted (NSM) CFRP strips: Current status and research needs

Abstract: The near-surface mounted (NSM) FRP strengthening technique has attracted worldwide attention as an effective alternative to the externally bonded (EB) FRP strengthening technique. In the NSM FRP strengthening method, grooves are first cut in the concrete cover of a concrete member for the FRP reinforcement to be inserted and embedded using an adhesive. The NSM FRP method has many advantages over the EB FRP method, including a higher bonding efficiency and a better protection of the FRP reinforcement. Existing experimental studies have shown that FRP strips owned a better bond efficiency compared with other section shapes (e.g. round bars and square bars), due to the fact that they had a larger perimeter-to-cross-sectional area ratio. This paper presents a state-of-the-art review, particularly on the flexural strengthening of RC beams with NSM CFRP strips. The observed failure modes in laboratory experiments of such FRP-strengthened RC beams are classified and the existing strength models are examined along with the failure mechanisms behind. The main knowledge gaps to be bridged in future studies are also identified. This review partially formed the basis of the development of design provisions on the NSM strengthening technique in the relevant Hong Kong design guideline.

Quasi-static and dynamic tensile properties of basalt fibre reinforced polymer

Abstract: Basalt Fibre Reinforced Polymer (BFRP) has been becoming more and more popularly used in structural strengthening and rehabilitation due to its advantages of high strength to weight ratio, easy to install, and anti-corrosion During the service life, BFRP strengthened structures might be subjected to dynamic loadings such as blast and impact loads It is essential to understand the material mechanical properties, especially the dynamic material properties of BFRP for reliable predictions of the performances of BFRP strengthened structures subjected to dynamic loads Very limited study on the static and dynamic tensile properties of BFRP material is available in the literature In this study, quasi-static and dynamic tests of the unidirectional BFRP with a unit weight of 300 g/m2 were conducted to examine the material properties of tensile strength, modulus and failure strain at various strain rates The strain rate sensitivity on the material properties of BFRP was analyzed and discussed Empirical formulae for the strength, elastic modulus and failure strain of BFRP material were proposed to estimate the dynamic enhancement at different strain rates

FRP reinforcement for concrete structures: state-of-the-art review of application and design

Abstract: Fiber reinforced polymers (FRPs) are considered to be a promising alternative to steel reinforcement, especially in concrete structures subjected to an aggressive environment or to the effects of electromagnetic fields. Although attempts to develop effective reinforcement have been followed, the application of FRPs remains limited by the solution to simple structural problems that mainly appear due to the absence of design codes, significant variation in the material properties of FRP composites and limited knowledge gained by engineers as regards the application aspects of FRP composites and structural mechanics of concrete elements reinforced with FRPs. To fill the latter gap, the current state-of-the-art report is dedicated to present recent achievements in FRPs applying practice to a broad engineers’ community. The report also revises the manufacturing process, material properties, the application area and design peculiarities of concrete elements reinforced with FRP composites. Along the focu...