Papers by Keyword: Flexural Capacity

Abstract: Traditionally, reinforced concrete structures are constructed using steel rebars as reinforcement which is more susceptible to reinforcement corrosion in severe exposure conditions. This leads to many disadvantages, like deterioration of concrete, reduction in strength, and increase in maintenance costs, which leads to a decrease in the serviceability of critical infrastructure. Fiber Reinforced Polymer bars are often used as alternative materials for steel bars because they are anti-corrosive, exhibit an excellent strength-to-weight ratio and are easy to handle but the main disadvantage is its brittle nature. Hence, the combination of steel and FRP bars was effectively used to augment both flexural capacity and ductility. As the ductility performance of hybrid Reinforcement is lower than conventional reinforced beams, Polyvinyl Alcohol Fibers in volume fraction were added in this investigation. The present investigation aims to determine the flexural capacity of reinforced concrete beams using Glass Fiber Reinforced Polymer (GFRP) bars and Steel bars. The optimum dosage of PVA fibers while evaluating compressive and split tensile strength is observed at 0.25% in volume fraction. Total six types of concrete beam specimens with and without PVA fibers were experimentally under four-point bending test tested such as beams reinforced with only steel bars, only GFRP bars, GFRP and steel bars. From the experimental results, it is observed that inclusion of PVA fibers in proposed beams with hybrid reinforcement enhanced the crack resistance by 80% and ultimate load capacity by 39% when compared with conventional beam.

Abstract: Traditionally, reinforced concrete structures are constructed using steel rebars as reinforcement which is more susceptible to reinforcement corrosion in severe exposure conditions. This leads to many disadvantages, like deterioration of concrete, reduction in strength, and increase in maintenance costs, which leads to a decrease in the serviceability of critical infrastructure. Fiber Reinforced Polymer bars are often used as alternative materials for steel bars because they are anti-corrosive, exhibit an excellent strength-to-weight ratio and are easy to handle but the main disadvantage is its brittle nature. Hence, the combination of steel and FRP bars was effectively used to augment both flexural capacity and ductility. As the ductility performance of hybrid Reinforcement is lower than conventional reinforced beams, Polyvinyl Alcohol Fibers in volume fraction were added in this investigation.The present investigation aims to determine the flexural capacity of reinforced concrete beams using Glass Fiber Reinforced Polymer (GFRP) bars and Steel bars. The optimum dosage of PVA fibers while evaluating compressive and split tensile strength is observed at 0.25% in volume fraction. Total six types of concrete beam specimens with and without PVA fibers were experimentally under four-point bending test tested such as beams reinforced with only steel bars, only GFRP bars, GFRP and steel bars. From the experimental results, it is observed that inclusion of PVA fibers in proposed beams with hybrid reinforcement enhanced the crack resistance by 80% and ultimate load capacity by 39% when compared with conventional beam.

Abstract: In this paper, the mechanical behavior of steel-concrete composite slim beams was investigated by experiments, and the influence of sectional dimension of steel beams on the bending stiffness and flexural capacity of composite slim beams was evaluated. Test results show that good cooperative performance can be achieved in steel-concrete composite slim beams and the relative slip between steel and concrete is very small. The steel-concrete slim beam presents considerable deformation ability beyond the service stage, which indicates that the composite slim beam has good ductility. In addition, sectional dimension of steel beams is proved to have significant influence on both the bending stiffness and flexural capacity of composite slim beams.

Abstract: The small-scale reinforced high calcium fly ash geopolymer concrete beams with short shear span were studied in this research. Reinforced concrete beams with 150x150 mm² cross-section and 530 mm in length were used for tests. Conventional reinforced Portland cement concrete beams (RC) with designed concrete compressive strengths of 35, 45 and 55 MPa and high-calcium fly ash geopolymer reinforced concrete beams with similar strength were tested. The geopolymer concretes (GC) were designed with alkaline liquid to fly ash ratio (L/A) of 0.5, sodium silicate to sodium hydroxide (S/H) ratio of 1.0 and two sodium hydroxide (NaOH) concentrations of 10M and 15M. Two temperatures of 23 and 60 °C were used for curing geopolymer reinforced concrete (GRC) beams for 24 hr, while RC beams were moist cured at 23 °C. The maximum sustained moment and shear were compared with the predicted values from the RC-design standard. The results showed that the failure patterns of small GRC beams were different to that of normal RC beam. The small GRC beams failed in flexure whereas the similar small RC beams failed in shear. However, the GRC beams were able to sustain higher shear and moment than the values obtained from the design code. The different in failure mechanism was probably due to the different in modulus of elasticity of geopolymer concrete and normal concrete.

Abstract: Steel Corrosion affects severely on the life and durability of RC structures. In order to investigate the relationship between partial corrosion of RC beams and its cracking morphology and flexural capacity, based on experimental data, RC partial corrosion beam models are simulated using finite element software to model the flexural cracks and capacity of corroded RC beam under different corrosion rates. The results of compared analysis with experiment are presented: with the increase of the corrosion rate, the cracking region is almost consistent, the number of cracks reduces gradually, crack spacing becomes more unequal, bending stiffness and yield strength greatly reduce, ultimate flexural capacity and energy absorption capacity deteriorates, numerical simulation results are in good agreement with experiment.

Abstract: Fiber reinforced polymer (FRP) has been applied not only for the simple structures but also for the advanced structures such as bridges or highway bridges for sustainable construction. In case of bridges or highway bridges, the structures experience not only static loadings but also fatigue loadings that may limited the serviceability of the bridge structures. In order to extend of the application of FRP on the such bridge structures to have a sustainable structures, the flexural capacity due to fatigue loading should be clarified. Glass composed FRP sheet namely Glass Fiber Reinforced Plastics (GFRP) is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. Many studies have been done to investigate the flexural capacity of concrete beams strengthened using GFRP sheets. However, studies on the flexural capacity after fatigue loadings are still very rarely. This study presented the results of experimental investigation on the flexural capacity of the strengthened concrete beams after fatigue loadings. A series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. Results indicated that after 800000 time of load cycle, the flexural capacity of beams specimens may decrease to only approximately 60%. The beam failed due to delaminating of GFRP sheet.

Abstract: One of the most common causes of damage to concrete structures is the corrosion of the reinforcement. Reinforcement made from Fiber Reinforced Polymers (FRP) is considered as an attractive substitution of traditional steel reinforcement. A different technical characteristic of fiber reinforced polymer makes designing structures with FRP reinforcement differs from conventional reinforced concrete design. Therefore, it is necessary to identify the differences and limitations of their use in the concrete structures, taking into account their material and geometrical features. Basalt Fiber Reinforced Polymer (BFRP) is a relatively new material for reinforcing bars. On the basis of the ACI 440.1R-06 guidelines as well as experimental results for selected BFRP reinforced beams a model of compatibility in a system: BFRP bar - concrete was proposed. Additionally, based on the results of FEM simulations, the effect of BFRP bars ribbing on their adhesion to concrete was discussed.

Abstract: Concrete filled double skins steel tube is a new components which is based on concrete filled steel tubular and use inner steel tube instead of core concrete. The components have many advantages such as little weight, good resistance for earthquake, good stiffness for resist bending and good performance for resist fire, and has been used in bridge pier, high-rise buildings, power transmission tower and so on. While these structures may inevitably suffer impact which comes from vehicles, ships, aircraft, etc. the structures which is impacted have taken much attention. This article will analysis dynamic behavior of concrete filled double steel tube under impact with simply supported, and propose formula of dynamic bearing capacity, laid the foundation for the analysis of impact performance of CFDST.

Abstract: Plate girders with corrugated webs with angles were developed in order to promote the flange local buckling strength of conventional plate girders with corrugated webs. The width to thickness ratio of flanges can be reduced with angles. However corrugated webs cannot contribute to the flexural stiffness and strength of PGCW, corrugated webs of PGCW-A can. A full-scale test was conducted to evaluate the flexural capacity of PGCW-A. As a result, the flexural capacity of a specimen of PGCW-A increased by 163% compared to a specimen of PGCW.

Abstract: In the High-rise building construction, the selection, combination and optimization of top-down method have not been systematized to date and rely on experience and appraisal. In this article, four classes of parameters are selected according to the different nature of the factors influencing the design of top-down method so as to conduct systematized reorganization and analysis of the geological situation, structural characteristics, construction quality and term, and economic efficiency of the building. This study proposes several tables classifying the influencing factor, establishes selection criteria and suggests detailed flowchart for the planning of top-down method. Case study confirms the suitability of the resulting top-down method planning, and derives and combines the optimized method to provide fast construction.