Top PDF Applications of FRP in reinforcing and strengthening concrete masonry beams

Applications of FRP in reinforcing and strengthening concrete masonry beams

Applications of FRP in reinforcing and strengthening concrete masonry beams

• Prisms having 3" grout cores exhibited a relatively better performance than rest of the specimens. The average compressive strength was 12.4 MPa, demonstrating more than 100% inc[r]

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EFFECTIVE FIRE PROTECTION MEASURES FOR FIELD DEPLOYMENT OF FRP STRENGTHENED CONCRETE BEAMS

EFFECTIVE FIRE PROTECTION MEASURES FOR FIELD DEPLOYMENT OF FRP STRENGTHENED CONCRETE BEAMS

Fire is a catastrophic unpredictable event that can result in numerous casualties in addition to certain financial loss. Nowadays, with the growing number of terrorist attacks, both public and military infrastructures are increasingly in danger of fire events. Therefore, researchers have been developing standards and guidelines for testing and evaluating the fire resistance of different building materials and structural elements under fire events. Significant progress has been made in evaluating the fire resistance of common building materials such as steel, concrete, and wood. However, with the advancement in construction industry, new building materials such as Fiber Reinforced Polymers (FRP) emerged and have been deployed in several structural applications. Since their emergence in the civil engineering market in the 1950s, FRP materials have drawn the attention of many researchers and engineers. FRPs are distinguished as high-strength, light-weight, and corrosion-free building materials that can be employed in different structural applications such as reinforcing, stiffening, and strengthening.
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Strengthening Of Concrete Structures Using Frp Laminates

Strengthening Of Concrete Structures Using Frp Laminates

Glass fibres are used as a reinforcing agent to form a very strong and relatively light weight fibre reinforced polymer composite material, it is called glass reinforced polymer. GFRP is a strong light weight material and it used for many products. Although it is not as strong and stiff as composites based on carbon fibre, it is less brittle and its raw materials are much cheaper. Although fibre glass used in many applications like swimming pools, septic tanks, water tanks and also in rehabilitation of concrete structures.
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Repair & Strengthening of Distressed/Damaged Ends of Prestressed Beams with FRP Composites

Repair & Strengthening of Distressed/Damaged Ends of Prestressed Beams with FRP Composites

The use of externally bonded and NSM FRP for the flexural and shear strengthening of concrete girders has been proven effective for most general purpose applications. The particular application being investigated in this study, however, presents additional challenges and introduces factors that may not be addressed in current design guidelines. Due to the localization of damage at the girder ends, a concentration of FRP material near the girder end is needed. Since the FRP material may only extend just past the bearing area, the behavior of FRP laminate repairs when tested with a low shear span-to-depth ratio should be investigated. This would ensure shear cracks develop within the damaged zone. As a result, the behavior will be governed by arch action rather than beam action. Previous research has concluded that the effectiveness of externally bonded FRP shear reinforcement decreases as shear span-to-depth ratio decreases (Ary and Kang 2012; Bousselham and Chaallal 2006; Belarbi et al. 2011). This could further limit the usefulness of FRP shear laminates in this particular application. In their design guidelines for FRP shear reinforcement systems, Belarbi et al. (2011) state that the design provisions are only applicable to beams with a shear span-to-depth ratio greater than 2.5. That is because reduction factors were developed from tests with sufficient shear span-to-depth ratios to assume plane sections remain plane after deformation. Additionally, the effectiveness of an FRP repair when combined with a conventional mortar repair should be investigated to determine the material’s suitability for this particular application. The interactions between the base concrete, mortar, and FRP may generate a complex strain field within the girder web, differing from that seen in cases where the FRP is added to an undamaged girder.
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A Parametric Study on the Flexural Strengthening of Reinforced Concrete Beams with Near Surface Mounted FRP Bars

A Parametric Study on the Flexural Strengthening of Reinforced Concrete Beams with Near Surface Mounted FRP Bars

Over the several last decades, strengthening of existing structures including reinforced concrete beams, slabs, walls and columns through the externally bonded reinforcement (EBR) and the near surface mounted (NSM) methods with fiber reinforced polymer (FRP) has been successfully utilized in civil engineering applications due to its efficiency, effectiveness and ease of application for strengthening concrete structures in both flexure and shear. A laminate or textile bond onto the surface of concrete elements in externally bonded method (EPR) while the near surface mounted method consists of placing fiber reinforced polymer bars into grooves precut on the concrete members and embedding them with a high-strength adhesive [6]. The efficiency of using FRP for strengthening of reinforced members according to the near surface mounted (NSM) method is widely proven in comparison to the externally bonded reinforcement (EBR) due to the fact that, the tensile strength of fiber reinforced polymer is better exploited [7]. Moreover, application of fiber reinforced polymer (FRP) with the near surface mounted (NSM) method is an alternative to the externally bonded reinforcement technique to mitigate the risk of premature debonding failure [8, 9], deterioration of FRP materials, protection against environmental corrosion and temperature, better aesthetics, as well as delimit any imperfection accommodate to the installation procedure [10, 11]. Fracture of flexural components (FRP materials), detachment of FRP sheets from the structural elements and flaking of concrete in EBR scheme of strengthening lead an additional difficulty arising from the fact that only limited amount of FRP can be used to increase the beam flexural capacity [12]. However, application of near surface mounted technique is appropriate only if the cover of the internal reinforcement is sufficiently thick for the groove size to be accommodated [5]. It worth mentioning that, the performance of the near surface mounted bars in strengthening of existing reinforced concrete elements is affected by local bond slip behavior, surface characteristics of FRP bars and treatments of reinforcement and grooves, interactions of FRP rods with the surrounding materials, geometry of FRP bars, and the concrete cover [7, 13].
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Using engineering cementitious composites as an adhesive for near-surface mounted FRP bars strengthening concrete/masonry structures

Using engineering cementitious composites as an adhesive for near-surface mounted FRP bars strengthening concrete/masonry structures

While the first instance of near surface mounted (NSM) strengthening was documented in 1949, it is only since the early 2000’s that NSM has experienced a resurgence in research attention. This may be due to the availability of fibre reinforced plastic (FRP) reinforcement which makes retrofitting existing structures much easier due to its low weight and high strength properties. It may also be due to the ever increasing volume of structures which require strengthening. It is most likely a combination of both factors. Engineered Cementitious composites (ECC) are coming to a point in their research lifecycle where development where their physical characteristics and potential benefits of ECC are well known and backed up by significant experimental data. It is now necessary for research to be conducted to identify real world applications and prove ECC a valid competitor to current industry norms. It is essential that ECC demonstrates comparable strength and durability as well as offering at least a material cost benefit. ECC is a generic term for cementitious matrix reinforced with any fibre, however in this study PVA fibres will be used. This will allow the study to leverage multiple works by Li and Hesse in an attempt to reduce the volume of testing required.
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Study on Strengthening of RC Beams by Hybrid FRP Bars

Study on Strengthening of RC Beams by Hybrid FRP Bars

(CFRP, GFRP, and HYBRID) composites in order to study their characteristics. Many practical applications worldwide now confirm that the technique of bonding FRP laminates or plates to external surfaces and usage of internal bars is a technically sound and practically efficient method of strengthening and upgrading of reinforced concrete load- bearing members that are structurally inadequate, damaged or deteriorated. Of all the materials used as reinforcement, carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP) composite materials have found special favour with engineers and applicators because of their many advantages. After that over a period of time some researchers started doing their work on Hybrid FRP (combined layer of FRP bars and laminates).Such kind of a material is a carbon rod panel (CRP). It consists of small diameter carbon rods attached with a backing .These panels are then externally bonded to the structures to strengthen them.
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REINFORCING AND REHABILITATIVE PERFORMANCE OF BASALT FIBRE REINFORCED POLYMERS FOR CONCRETE BEAMS

REINFORCING AND REHABILITATIVE PERFORMANCE OF BASALT FIBRE REINFORCED POLYMERS FOR CONCRETE BEAMS

The use of BFRP composite for flexural rehabilitation and strengthening of reinforced concrete beams was successfully demonstrated with this study. It was shown that BFRP composite can increase the ultimate and yield loads for strengthened beams and restore the service and yield loads for rehabilitated beams. The use of BFRP in flexure also resulted in significantly reduced crack widths, further proving the ability of BFRP to enhance the durability of reinforced concrete structures by hindering further ingress of salt solution in concrete flexural elements in cold climates. However, it was also found that if insufficient cross-strapping is provided, beams can fail by sudden interfacial debonding, which should be avoided. It was shown that a scheme where the flexural composite is cross- strapped along its entire length is most effective. Future work should focus on studying the strengthening effect of BFRP with varying flexural reinforcement ratios and comparisons should be made to equivalent strengthened beams with other common FRP materials such as GFRP and CFRP.
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Torsional Strengthening of Reinforced Concrete Beams Using CFRP Composites

Torsional Strengthening of Reinforced Concrete Beams Using CFRP Composites

38 In this study, the twisting moment was applied through reversed point loads bending moment developed in the test span. Fiber orientations ±45 and 0/90 degrees were used. The CFRP material properties were the same as what was previously used by Norris et al. (1997). The thickness, 1mm/layer, was obtained from the Theoretical Moment Resistance by Andre (1995). In this study, concrete was modelled by a three dimensional (3D) structural RC Solid element, Solid65 (a finite element parameter). This element has eight nodes with three translational degrees of freedom at each node which made it capable of cracking in tension zones and crushing in compression zones. This element treated non- linearity in material properties very well. The reinforcements, on the other hand, were modelled by Link8 (a type of element used in FEA for modelling reinforcing bars), a 3D Spar element with eight nodes for which each node has three translational degrees of freedom. And for the FRP sheets, the Solid46 (a type of element used in FEA) was used to model them. The bond between steel reinforcements and concrete was assumed to be perfect with no bond loss (Kachlakev 2001; Fanning 2001) by connecting the Link8 and the Solid 65 elements at their nodes. Same concept was used for the bonding of CFRP with concrete. The program results closely follow the experimental results reported by Gesund (1964). The results show excellent conformance between the experimental and the analytical works as soon as the cracking stage in concrete started, as shown in the accompanying curve. For retrofitted RC beams, this was very interesting because the FRP effectively contributed to the strength after cracks began to form. Load-deflection curves of different twisting-to-bending moment ratios show that CFRP wrapping did not
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Shear capacity of non metallic (FRP) reinforced concrete beams with stirrups

Shear capacity of non metallic (FRP) reinforced concrete beams with stirrups

The beams were tested monotonically under four point bending by means of 500 and 1000 kN hydraulic actuator. Each beam was loaded continuously to failure with each load increments approximately 5% from its theoretical ultimate load. A part of operation was manually controlled and some necessary adjustments were made to keep the load constantly during the test. The electrical-resistance strain gauges were used to measure tensile strains along reinforcing bars, stirrups and compressive area in concrete with a 5 mm long, 3 mm long and 60 mm long, respectively. Fig. 2 shows the strain gauge positions along the reinforcing bars and denoted as B1, B2 and B3. Whereas strain gauges denoted as SG were attached on selected stirrups. Concrete strain gauges were also bonded at the top compression surface at the mid-span and indicated as C. All the strain gauges were fully wrapped and waterproofed before casting. To measure the deflection of the beam, three linear variable displacement transducers (LVDTs) with a 50 mm stroke were placed at the mid-span and under the load positions. During the test, all crack formation and propagation on both sides of the beam surfaces were marked and labelled with the corresponding incremental loads.
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Shear design of reinforced concrete beams with FRP longitudinal and transverse reinforcement

Shear design of reinforced concrete beams with FRP longitudinal and transverse reinforcement

Bentz et al. [29] developed an experimental program of 11 shear tests of FRP RC beams, 5 of them with and 6 without GFRP stirrups. The beams showed different longitudinal GFRP reinforcement ratios and different transverse GFRP reinforcement ratios ( ρ t = A t /s/b w ). In relation to the failure mode of the tests with stirrups, Bentz et al. [29] reported that beam L05-1 failed in shear by stirrup rupture at the bottom bent zone with a maximum measured strain at mid-height of the beam of 55% the bare-bar rupture strain. Beam L05-2 failed at flexure, even though shear failure was imminent. Beam L20-1 failed by sliding along a large diagonal crack, showing the rupture of the stirrups at failure. Beam L20-2 failed in flexure by concrete crushing with the rupture of some stirrups. Bentz et al. [29] concluded that, with multiple layers of longitudinal bars, the stirrups rupture did not occur at the bent location (as in beam L05-1) but near the end of the lap-splice (L20-2).
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Deflection behaviour of FRP reinforced concrete beams and slabs: An experimental investigation

Deflection behaviour of FRP reinforced concrete beams and slabs: An experimental investigation

The results of this study indicate that additional deformations other than those induced by pure flexure could be significant particularly in FRP RC beams and slabs with moderate to high reinforced ratio. However, it seems that most of the existing simplified methods to predict deflections of FRP RC elements do not adequately take into account these additional deformations. This usually leads to un-conservative predictions especially at higher load levels. It should be mentioned that additional deformations may not always be significant at the serviceability load. Nevertheless, it is still important to predict deformation of FRP RC elements over the entire loading range with good accuracy. This requires developing more fundamental methods to evaluate shear and bond-slip induced deflections [24, 25]. Further analytical investigations will be published by the authors in a separate, forthcoming paper.
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Impact resistance of ultra-high strength concrete beams with FRP reinforcement

Impact resistance of ultra-high strength concrete beams with FRP reinforcement

Composite materials, including Fibre Reinforced Polymer (FRP) bars, have been used for decades in the structural and civil engineering sectors over traditional steel reinforcement. The main reasons for this are that FRP composites possess a number of advantages. They are non-corrosive, non-conductive, and lightweight and possess high longitudinal tensile strength. This paper presents the results of an experimental investigation into the effects of the use of glass FRP (GFRP) bars as internal reinforcement on the behaviour of concrete beams with high strength concrete (HSC) and ultra-high strength concrete (UHSC). Both static and dynamic (impact) behaviours of the beam have been investigated. Twelve GFRP reinforced concrete (RC) beams were designed, cast and tested. Six GFRP RC beams were tested under static loading (three point bending) to examine the failure modes, load carrying capacity, deflection and energy absorption capacities. The other six GFRP RC beams were tested under impact loading using a drop hammer apparatus at various levels of impact energy. It was found that the use of UHSC in conjunction with larger amounts of tensile reinforcement showed higher levels of post-cracking bending stiffness. GFRP RC beams under static loading displayed a flexural response at failure. The GFRP RC beams under impact loading displayed a dynamic punching shear failure response at various levels of impact energy.
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Simulating FRP Debonding From Concrete Surface in FRP Strengthened RC Beams: A Case Study

Simulating FRP Debonding From Concrete Surface in FRP Strengthened RC Beams: A Case Study

A parameter must also be dened for measuring the reduced stiness of the element after debonding. Either of the two parameters of relative displacement or work done by the interfacial stresses in the software may be exploited for this purpose. In the present study, the work done by the interfacial stresses based on Eq. (2) has been used. In this case, the element's stiness is reduced in proportion to the work done by the interfacial stresses until the work reaches the value dened by the user for fracture energy [20]. Evidently, the interfacial fracture energy which is equal to the area under the stress-slip curve needs to be dened. The fracture energy may be independently dened for each of the three directions. Based on these observations, it is clear that fracture energy in t and s directions will be determined from Eq. (1d), and the fracture energy of concrete under tension which is equal to the area under the stress-tensile strain curve will be obtained from the following relation [20]:
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TRM versus FRP in flexural strengthening of RC beams: behaviour at high temperatures

TRM versus FRP in flexural strengthening of RC beams: behaviour at high temperatures

Table 1 supporting by Fig. 2a, provide description of the tested specimens and strengthening configurations. The strengthened specimens were named following the notation BN_F_T, where B denotes the type of bonding agent (M for cement mortar and R for epoxy resin); N the number of TRM or FRP layers; F the type of textile fibres material (C for dry carbon fibres, CCo for coated carbon fibres, BCo for basalt fibres and G for glass fibres); and T denotes the temperature at which the specimens were exposed (20 ° C or 150 ° C). For the specimens receiving U-jackets at their ends (Fig. 2b), an additional suffix (EA-End anchorage) is added to the notation. For example, ‘M3_C_20’ refers to a beam strength- ened with 3 layers of dry carbon TRM and tested at 20 ° C, whereas ‘R3_C_EA_150’ refers to a beam strengthened with 3 layers of car- bon FRP, anchored at its ends using two layers of U-shaped jacket, and tested at temperature of 150 ° C. It is noted that the axial stiff- ness of seven layers of glass or basalt-fibre textile are approxi- mately equivalent to one layer of carbon-fibre textile. Table 1 gives the normalized axial stiffness of the textile reinforcement used in all specimens (normalized to one layer of carbon-fibre textile).
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Strengthening of Shear Deficient RC T-Beams with Externally Bonded FRP Sheets

Strengthening of Shear Deficient RC T-Beams with Externally Bonded FRP Sheets

Siddiqui (2009) has studied the experimental investigation of RC beams strengthened with externally bonded fiber reinforced polymer (FRP) composites. Use of externally bonded FRP sheets/strips/plates is a modern and convenient way for strengthening of RC beams. Although in the past substantial research has been conducted on FRP strengthened RC beams, but the behaviour of FRP strengthened beams under different schemes of strengthening is not well established. In this study, practical FRP schemes for flexure and shear strengthening of RC beams has been studied. For this purpose, 6 RC beams were cast in two groups, each group containing 3 beams. The specimens of first group were designed to be weak in flexure and strong in shear, whereas specimens of second group were designed just in an opposite manner i.e. they were made weak in shear and strong in flexure. In each group, out of the three beams, one beam was taken as a control specimen and the remaining two beams were strengthened using two different carbon fiber reinforced polymer (CFRP) strengthening schemes. All the beams of two groups were tested under similar loading. The response of control and strengthened beams were compared and efficiency and effectiveness of different schemes were evaluated. It was observed that tension side bonding of CFRP sheets with U- shaped end anchorages is very efficient in flexural strengthening; whereas bonding the inclined CFRP strips to the side faces of RC beams are very effective in improving the shear capacity of beams. He concluded that for shear strengthening, externally bonded inclined CFRP-strips show a far better performance than vertical CFRP-strips as specimen strengthened using inclined strips gives higher shear and deformation capacity than specimen strengthened using vertical strips. Also the inclined CFRP-strips arrest the propagating cracks more effectively than the vertical CFRP-strips.
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Strengthening of Shear Deficient RCL and .T- Beams with Externally Bonded FRP Sheet

Strengthening of Shear Deficient RCL and .T- Beams with Externally Bonded FRP Sheet

The rehabilitation of existing reinforced concrete (RC) bridges and building becomes necessary due to ageing, corrosion of steel reinforcement, defects in construction/design, demand in the increased service loads, and damage in case of seismic events and improvement in the design guidelines. Fiber-reinforced polymers (FRP) have emerged as promising material for rehabilitation of existing reinforced concrete structures. The rehabilitation of structures can be in the form of strengthening, repairing or retrofitting for seismic deficiencies. RC T-section is the most common shape of beams and girders in buildings and bridges. Shear failure of RC T- beams is identified as the most disastrous failure mode as it does not give any advance warning before failure.
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Shear Capacity of Non-Metallic (FRP) Reinforced Concrete Beams with Stirrups

Shear Capacity of Non-Metallic (FRP) Reinforced Concrete Beams with Stirrups

The beams were tested monotonically under four point bending by means of 500 and 1000 kN hydraulic actuator. Each beam was loaded continuously to failure with each load increments approximately 5% from its theoretical ultimate load. A part of operation was manually controlled and some necessary adjustments were made to keep the load constantly during the test. The electrical-resistance strain gauges were used to measure tensile strains along reinforcing bars, stirrups and compressive area in concrete with a 5 mm long, 3 mm long and 60 mm long, respectively. Fig. 2 shows the strain gauge positions along the reinforcing bars and denoted as B1, B2 and B3. Whereas strain gauges denoted as SG were attached on selected stirrups. Concrete strain gauges were also bonded at the top compression surface at the mid-span and indicated as C. All the strain gauges were fully wrapped and waterproofed before casting. To measure the deflection of the beam, three linear variable displacement transducers (LVDTs) with a 50 mm stroke were placed at the mid-span and under the load positions. During the test, all crack formation and propagation on both sides of the beam surfaces were marked and labelled with the corresponding incremental loads.
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Performance of lightweight granulated glass concrete beams reinforced with basalt FRP bars

Performance of lightweight granulated glass concrete beams reinforced with basalt FRP bars

Moreover, their non-corrosive, non-magnetic properties offer ideal solutions for external reinforcement and for applications where interferences with magnetic fields need to be avoided. Hollaway (2010) reported that at present, bridges, parking garages, highway infrastructure, marine environments, and chemical plants are sizeable examples of places where applications of FRP have been carried out fruitfully. Compared with conventional steel reinforcement, FRP rebars have a relatively low modulus of elasticity, low linear stress-strain behaviour until failure, and different bond properties, hence different structural response is expected. Nanni (2003) states that the design of FRP reinforced structures are often governed by the serviceability limit states (SLS), as the lower stiffness of FRP bars can lead to large strains under small loads resulting in large crack widths and deflections. Due to the variation of different mechanical and bond properties of FRP, that is primarily dependent on the category of fibre and manufacturing process; its design codes are not yet standardised. Although some studies have been focused on the investigation of the flexural behaviour of FRP reinforced concrete beams, there are insufficient experimental data and comparisons, particularly on lightweight and foam glass constituted elements. The use of granulated foam glass in concrete elements, particularly as beams and slab elements, provides a unique opportunity to reduce significantly, the permanent actions on superstructural and substructural elements. Whereas limited research has been done on concrete structural elements reinforced with conventional steel rebars, (Khatib et al., 2012), limited studies appear to exist for reinforced concrete beams utilising BFRP rebars.
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Performance of lightweight granulated glass concrete beams reinforced with basalt FRP bars

Performance of lightweight granulated glass concrete beams reinforced with basalt FRP bars

The steel reinforced concrete beams consisted of 2no. 8 mm diameter high tensile steel rebars as main tension reinforcement. The first vertical flexural crack in the beams occurred at a relatively small load of between 20 - 35%, i.e. 15 – 21 kN of their ultimate load, in the constant bending moment region. With further load increase, additional flexural cracks developed along the span of the beam length. The cracks propagated outside the flexural zone and started to take a diagonal shape towards the compression fibres of the beam. However, the width of these flexural cracks did not change significantly, suggesting that they were all secondary flexural cracks. Secondary cracks are those that are widely spaced and occur under low loads without influencing other cracks to arise. These cracks develop during the initial stages of the cracking due to internal expansion and contraction of the concrete constituents as well as low flexural stresses accumulating from the self-weight of the beam. Hassoun and Al-Manaseer (2008) stated that, when steel bars are subjected to low tensile stresses, the widths of the cracks remain small, but the numbers of cracks increase. As the tensile stresses progress further, an equilibrium stage is reached. When the tensile stresses are further increased to a point, that between the steel and the concrete there is a difference in strain, then the second stage of the cracking starts to occur, where the widths of the cracks increase without any significant increase in the number of cracks. These cracks are known as the main cracks. Usually, one or two cracks start to widen more than the others, forming critical cracks. This was observed during the experiment from 36 – 45 kN loads for the specimens until failure. The cracks started to widen and extend towards the top compression fibres of the beams without any additional cracks forming. The beams continued to sustain
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