Behaviour of RC Beams Strengthened by CFRP under Fatigue Load

One of the major tasks for the construction industries worldwide is rehabilitation of structurally deteriorated or functionally obsolete reinforced concrete structures. The major portion of the infrastructure is built from reinforced concrete and corrosion of reinforcing steel was found to be one of the principal cause of deterioration. The solution to this task has been proved by the use of externally bonded carbon fibre reinforced polymer (CFRP) strips to strengthen reinforced concrete structures. In this study, the behaviour of reinforced concrete beams strengthened with externally bonded carbon fiber reinforced plastic (CFRP) under fatigue load were investigated. The capacity of CFRP strengthened beams subjected to fatigue loads, fatigue characteristics of reinforced concrete beam strengthened by CFRP, fatigue life and behaviour of the reinforced concrete beam were studied. Data obtained from experimental investigations were statistically analyzed and valid correlations were obtained

Behaviour of RC Beams Strengthened by CFRP under Fatigue Load

One of the major tasks for the construction industries worldwide is rehabilitation of structurally deteriorated or functionally obsolete reinforced concrete structures. The major portion of the infrastructure is built from reinforced concrete and corrosion of reinforcing steel was found to be one of the principal cause of deterioration. The solution to this task has been proved by the use of externally bonded carbon fibre reinforced polymer (CFRP) strips to strengthen reinforced concrete structures. In this study, the behaviour of reinforced concrete beams strengthened with externally bonded carbon fiber reinforced plastic (CFRP) under fatigue load were investigated. The capacity of CFRP strengthened beams subjected to fatigue loads, fatigue characteristics of reinforced concrete beam strengthened by CFRP, fatigue life and behaviour of the reinforced concrete beam were studied. Data obtained from experimental investigations were statistically analyzed and valid correlations were obtained

STRENGTHENING OF REINFORCED CONCRETE BEAMS WITH OPENINGS USING CFRP LAMINATES

Holes or openings are required to be provided through beams to facilitate services in buildings, i.e. commercial and residential. Such services are usually electrical cables, water supplies, air-conditioning, network cables and ventilation system accommodated in utility pipes and ducts. However, the provisions of openings in reinforced concrete (RC) beams have caused many problems to the beam behaviour. The change in the beam cross-sectional area changes the beam engineering behaviour. The change in the mechanical properties also causes cracking and deflection as well as reduction of the beam stiffness and capacity

A Numerical Study of Brace-Viscous Damper System of Fixed Offshore Jacket Platforms Under Extreme Environmental Loads

The Persian Gulf is one of the most common regions where offshore platforms exist due to the presence of oil and natural gas. Wind, current, and wave loading affect the dynamic response of offshore structures, increasing performance uncertainty and catastrophic failure probability. Thus, this study investigates energy dissipation systems, particularly viscous dampers, to solve design and rehabilitation problems of fixed offshore structures. Viscos dampers improve vibrational behaviour and reduce structural response to optimise platform performance. Thus, eliminating costly structural repairs and strengthening components under extreme environmental loads extends structure lifetime. Thus, different viscous damper system configurations are tested to reduce dynamic response under extreme environmental loads in the Persian Gulf. Diagonal and inverted V-shaped brace viscous dampers with nine different arrangements are compared to find the best configuration. The study found that the brace viscous dampers with only three applied dampers at the top three levels are most efficient at mitigating dynamic response. It reduced displacements from level 1 to level 5 by 52% to 64% and connection stresses by 38% to 54%. Finally, viscous dampers reduce structural vibration and provide uniform and constant structural dynamic response, so the oil and gas industry should use them for offshore structure design and rehabilitation

A Numerical Study of Brace-Viscous Damper System of Fixed Offshore Jacket Platforms Under Extreme Environmental Loads

The Persian Gulf is one of the most common regions where offshore platforms exist due to the presence of oil and natural gas. Wind, current, and wave loading affect the dynamic response of offshore structures, increasing performance uncertainty and catastrophic failure probability. Thus, this study investigates energy dissipation systems, particularly viscous dampers, to solve design and rehabilitation problems of fixed offshore structures. Viscos dampers improve vibrational behaviour and reduce structural response to optimise platform performance. Thus, eliminating costly structural repairs and strengthening components under extreme environmental loads extends structure lifetime. Thus, different viscous damper system configurations are tested to reduce dynamic response under extreme environmental loads in the Persian Gulf. Diagonal and inverted V-shaped brace viscous dampers with nine different arrangements are compared to find the best configuration. The study found that the brace viscous dampers with only three applied dampers at the top three levels are most efficient at mitigating dynamic response. It reduced displacements from level 1 to level 5 by 52% to 64% and connection stresses by 38% to 54%. Finally, viscous dampers reduce structural vibration and provide uniform and constant structural dynamic response, so the oil and gas industry should use them for offshore structure design and rehabilitation

Effect of Mixing Ingredient on Compressive Strength of ISSA Concrete Containing Eggshell Powder

Waste management is one of the alarming issues in developing country like Malaysia. It is reported that sewage sludge and eggshell waste are generated annually. The amount of waste is expected to increase from year to year. Thus it is viable to investigate the possibility to turn waste into suitable construction materials in concrete production. In this paper, sewage sludge and eggshell waste are treated and used as blended cement to reduce the use of cement consumption in concrete production. At early stage of research, mortar cubes of mm of cubes were cast to identify the optimum percentage of ISSA. At the second stage, only optimum percentage of ISSA concrete were added with difference percentages of eggshell powder and tested by slump test and compressive strength. All the specimens were subjected to water curing before undergo compressive strength test. The optimum of ISSA and eggshell powder were 10% and 15% which capable to use as partial cement replacement. The total cement replacement is 25%. The compressive strength result was 37% higher than normal plain concrete. On the right formulation, ISSA and eggshell can be used partial cement replacement that exhibit optimum strength

Effect of elevated temperature of hybrid fiber cement mortar

Concrete structures often subjected to damages such from fire and it can severely affect the stability of a concrete structure where cement is used as binding material. Hence, the aim of this experimental study is to investigate the effect of elevated temperature towards basalt fibre, bamboo fibre and combined fibres of bamboo and basalt fibres cement mortar, and to determine mechanical performance of different percentage of hybrid fibre concrete in terms compressive strength and flexural tensile strength. Cement mortar blocks (50 mm x 50 mm) and prisms (40 mm x 40 mm x 160 mm) with and without fibres are prepared. Basalt fibres of 0.1%, 0.25% and 0.5% and 0.5% of bamboo fibres by cement weight were added. The strength of the mortar exposed to various temperatures, 400 °C, 800 °C and 1000 °C for 2 hours was determined after curing for 28 days. The test result indicates that the optimum hybrid fibres was specimen th t contained 0.10% basalt fibre and 0.50% bamboo fibres. Even after being heated to 1000°C, the mortar that is produced with this mix showed the highest compressive strength. Overall, the combination of basalt and bamboo fibres can be seen to exhibit higher strength compared to single fibre specimens after elevated temperature

Natural Lime Treated as Partial Cement Replacement to Produce Concrete

In this study, eggshell powder was used as partial replacement of Ordinary Portland cement replacement at 5%, 10%, 15% and 20% in concrete production. Since the chemical composition of eggshell contain mainly of calcium oxide which is mostly similar to the natural lime sources. Thus the use of waste-products in cement industries is an environmental friendly while able to increase the industrialization instead of disposal of large numbers of waste materials that would pollute the land, water and air. The specimens were casted into concrete cube (100mm x 100mm x100mm) and beam (100mm x100mm x 500mm). The investigations focused on compressive, flexural strength and water absorption at different percentages of replacement and tested at 1, 7, 28, 56 and 90 days. From the investigation, it is found that the compressive strength and flexural strength increases up to 45% as compared to the control specimens when cement replacement by 15% of air-dry eggshell powder. Moreover, the rate of water absorption greatly reduces 55% when cement replacement by 15% of air-dry eggshell powder. Scanning electron microscope showed clear picture of the eggshell concrete contain less voids than normal plain concrete

Suitability of Using LA Abrasion Machine for the Nano Manufacturing of Palm Oil Fuel Ash and Incorporating in Mortar Mixture

Background: In order to enhance the properties of palm oil fuel ash-based mortar, researchers have explored the concept of reducing palm oil fuel ash (POFA) to a nanoscale. While previous studies have utilized ball milling machines with high grinding speed to achieve nano-scale POFA, the Los Angeles abrasion machine, which is more readily available and has a slower grinding speed, has been rarely employed. Objective: The study aimed to investigate the suitability of using a Los Angeles abrasion machine with a low grinding speed to produce nano palm oil fuel ash. This paper also provides a comparison of the effect of using the nano POFA with different particle sizes within the range of 982 to 150 nm on the mortar’s flowability and compressive strength. Methods: To produce nano-size palm oil fuel ash using the Los Angeles abrasion machine, the received palm oil fuel ash was thermally treated and ground using a Los Angeles abrasion machine with varying grinding periods. The grinding process parameters were kept constant, but second grinding periods of 50,000, 80,000, and 110,000 cycles were introduced. All three types of nano palm oil fuel ash were analyzed for their physical properties, chemical properties, morphology, and mineralogy. Furthermore, these nano palm oil fuel ashes were incorporated into a designed mortar mix along with micro palm oil fuel ash. The mortar’s fresh properties and compressive strength at different curing ages were observed and analyzed. The relationship between various factors, such as the replacement rate of micro, nano palm oil fuel ash, the grinding cycles of nano POFA, and the corresponding responses, specifically the compressive strength at different curing ages, was analyzed and explained using the response surface methodology. Results: The 110k cycle nano palm oil fuel ash had a smaller particle size of 103.1 nm, while a particle size of 529 nm and 325 nm was found in the 50k and 80k cycle nano palm oil fuel ash. In terms of the combination of micro and nano palm oil fuel ash in the mortar, increasing the dosage of nano palm oil fuel ash contributed to improvements in flow diameter and compressive strength. However, the opposite trend was observed with micro palm oil fuel ash. The optimal mix design for the combination involved using 10% micro and 2 to 3% nano palm oil fuel ash. This composition led to an improvement rate of 7.9%, 1.48%, and 4.6% in compressive strength at 7, 28, and 90 days, respectively. While, the response surface methodology’s numerical optimization also supported the use of a similar combination. However, it additionally recommended employing the 50,000-cycle nano palm oil fuel ash in the mortar for earlier curing stages, while the 110,000-cycle nano palm oil fuel ash was suggested for later curing stages. Conclusion: Los Angeles abrasion machine could be utilized to produce nano palm oil fuel ash with a particle size up to 103 nm with the aid of designed parameters. In this mortar mix design, the impact of a small variance in nano palm oil fuel ash’s particle size was trivial compared to the replacement rate of micro palm oil fuel ash on the mortar’s compressive strength

Impact of micro pofa and nano pofa in cementitious material : A review

The utilization of palm oil fuel ash as cement replacement in concrete and mortar mix design could be a solution for reducing the demand for cement. However, according to previous investigations palm ash-based concrete and mortar had lower fresh properties and hardened properties than usual concrete. Thus, modification of the ash’s particle sizes, as well as the mix design, was made and eventually nano palm ash was introduced into the mix design. This review article provides a detailed examination of the impact of particle size; micro and nano palm ash in concrete and mortar mix design to explore the potential of nano palm ash in future work. A detailed comparison between micro and nano palm ash in terms of ash particle characteristics, mix design, fresh properties and hardened properties are presented. Nano palm ash possesses lower unburnt carbon, higher silica content and smaller particle size than the micro palm ash. This led to the improvement in the nano palm ash-based concrete’s fresh properties and the early agehardened properties of concrete. Overall, the purpose of this review article is to provide a detailed understanding of the impact of micro and nano palm ash in cementitious materials