Enhancing the Performance of Knee Beam-Column Joint using Hybrid Fibers Reinforced Concrete

The knee beam-column joint is a critical location in a Reinforced Concrete (RC) structure particularly when subjected to earthquake vibrations. The current structural design codes dictate the use of high amounts of steel reinforcements in the frame joint to manage large strain demands in seismic-prone regions. However, these codes could result in the congestion of steel reinforcements in the limited joint area which can consequently produce numerous construction complications. This study aims to improve the structural performance of Knee Joint (KJ) by reducing the load induced to the embedded steel reinforcements during seismic vibrations. Hence, this study attempted to develop a Hybrid Fiber Reinforced Concrete (HyFRC) by combining multiple synthetic fibers to be introduced onto KJ. Six KJ specimens were cast using five developed HyFRC materials and one Control specimen to be experimentally tested under lateral cyclic loading. The results indicated significant improvements for the HyFRC KJ specimens particularly in energy dissipation capacity, stiffness degradation rate, displacement ductility toughness, steel reinforcement strain and hysteretic behavior. A total of six Finite Element (FE) KJ models were developed using the HyFRC materials to verify the results from the experimental testing. The accuracy of the proposed FE models resulted in average percentage differences of 25.89% for peak load, 3.45% for peak load displacement and 0.18% for maximum displacements from the experimental data. In conclusion, this study developed HyFRC materials that are beneficial in providing cost-efficient alternatives to Reinforced Concrete (RC) KJ structures in areas with low to moderate level of seismic risks

Correction to: Enhancing the Performance of Knee Beam–Column Joint Using Hybrid Fibers Reinforced Concrete

The knee beam–column joint is a critical location in a Reinforced Concrete (RC) structure particularly when subjected to earthquake vibrations. The current structural design codes dictate the use of high amounts of steel reinforcements in the frame joint to manage large strain demands in seismic-prone regions. However, these codes could result in the congestion of steel reinforcements in the limited joint area which can consequently produce numerous construction complications. This study aims to improve the structural performance of Knee Joint (KJ) by reducing the load induced to the embedded steel reinforcements during seismic vibrations. Hence, this study attempted to develop a Hybrid Fiber Reinforced Concrete (HyFRC) by combining multiple synthetic fibers to be introduced onto KJ. Six KJ specimens were cast using five developed HyFRC materials and one Control specimen to be experimentally tested under lateral cyclic loading. The results indicated significant improvements for the HyFRC KJ specimens particularly in energy dissipation capacity, stiffness degradation rate, displacement ductility toughness, steel reinforcement strain and hysteretic behavior. A total of six Finite Element (FE) KJ models were developed using the HyFRC materials to verify the results from the experimental testing. The accuracy of the proposed FE models resulted in average percentage differences of 25.89% for peak load, 3.45% for peak load displacement and 0.18% for maximum displacements from the experimental data. In conclusion, this study developed HyFRC materials that are beneficial in providing cost-efficient alternatives to Reinforced Concrete (RC) KJ structures in areas with low to moderate level of seismic risks

Structural performance of precast foamed concrete sandwich panel subjected to axial load

In this paper, experimental and simple analytical studies on the structural behavior of Precast Foamed Concrete Sandwich Panel (PFCSP) were reported. Full-scale tests on six PFCSP panels varying in thickness were performed under axial load applications. Axial load-bearing capacity, load-deflection profiles, load-strain relationships, slenderness ratio, load-displacement, load-deformation, typical modes of failure and cracking patterns under constantly increasing axial loads were discussed. Nonlinear Finite Element Analysis (FEA) using LUSAS software to investigate the structural behavior of PFCSP was contacted. The computed ultimate strength values using American Concrete Institute equation (ACI318) and other empirical formulas developed by pervious researchers which applicable to predict the ultimate strength capacity of sandwich panels were compared with the experimental test results and FEA data obtained; therefore, very conservative values resulted, a significant agreement with the FEA data that presented a high degree of accuracy with experiments and an increase in slenderness function

A review of the corrosion behavior of metallic heritage structures and artifacts

Awareness about restoring and preserving historically important structures and artifacts is gradually growing in many parts of the world. These artifacts and structures represent the culture, tradition and past of a nation. They are often also a source of national income through tourist activities. Besides masonry and wood work, metallic forms and relics are a vital part of the heritage which needs to be conserved. Certain metals have been used significantly throughout history in the creation of objects and structures. However, metals are prone to decay over time, particularly decay through corrosion. The basic mechanisms of metal corrosion, the various types of corrosion and existing remedial solutions are reviewed in this paper. The most significant factor affecting metal corrosion was found to be the surrounding environment, especially in marine areas. Different remedial measures can be implemented on corroded metals according to their specific properties. Recommendations for further study are offered at the end of the paper

Fire resistance of geopolymer concrete: a critical review

Although a novel inorganic family of geopolymer concrete (GPC) is a promising building material. The need for understanding its resistance against fire at high temperatures is considered essential to ensure its long-term durability. Physical examinations of the degree of cracking, spalling, brittleness, and loss of strength in GPC upon exposure to high temperatures and during fires provide an indicator of their resilience to such conditions. The addition of recycled fibers (RFs) to GPC has been reported as a strategy for overcoming these limitations and preventing concrete microstructure deterioration. Therefore, the development of RF-reinforced GPC (RF-RGPC) to resist fire has become research imperative. The use of RFs derived from industrial wastes provides additional benefits, such as waste reduction, resource conservation, reduced processing costs compared with virgin fibers, and the elimination of waste disposal in landfills. Moreover, RF-RGPC is an inorganic polymer binder made through the alkali activation of reactive aluminosilicate materials that comprise RFs, which increase its structural reliability. In this regard, conducting a critical literature review of current updates related to the fire performance of RF-RGPC subjected to elevated temperatures and during fires is urgently necessary. This study provides critical reviews on the type of RFs, spalling mechanism, physical inspection and properties of RF-RGPCs. It also comprehensively demonstrated the influence of fire on the properties of RF-RGPC after high temperature exposure. The major findings of this study are expected to introduce this unique, cutting-edge, accessible, and environment-friendly RF-RGPC as a promising, durable and heat- and fire-resistant building material for the current infrastructure and sustainable construction industries

Enhancing the Performance of Knee Beam– Column Joint using Hybrid Fibers Reinforced Concrete

The knee beam–column joint is a critical location in a Reinforced Concrete (RC) structure particularly when subjected to earthquake vibrations. The current structural design codes dictate the use of high amounts of steel reinforcements in the frame joint to manage large strain demands in seismic-prone regions. However, these codes could result in the congestion of steel reinforcements in the limited joint area which can consequently produce numerous construction complications. This study aims to improve the structural performance of Knee Joint (KJ) by reducing the load induced to the embedded steel reinforcements during seismic vibrations. Hence, this study attempted to develop a Hybrid Fiber Reinforced Concrete (HyFRC) by combining multiple synthetic fibers to be introduced onto KJ. Six KJ specimens were cast using five developed HyFRC materials and one Control specimen to be experimentally tested under lateral cyclic loading. The results indicated significant improvements for the HyFRC KJ specimens particularly in energy dissipation capacity, stiffness degradation rate, displacement ductility toughness, steel reinforcement strain and hysteretic behavior. A total of six Finite Element (FE) KJ models were developed using the HyFRC materials to verify the results from the experimental testing. The accuracy of the proposed FE models resulted in average percentage differences of 25.89% for peak load, 3.45% for peak load displacement and 0.18% for maximum displacements from the experimental data. In conclusion, this study developed HyFRC materials that are beneficial in providing cost-efficient alternatives to Reinforced Concrete (RC) KJ structures in areas with low to moderate level of seismic risks

Mechanics-based approach for predicting the short-term deflection of CFRP plated RC beams

Most design codes available today for predicting the deflection of adhesively plated RC beams use a full-interaction moment-curvature approach that requires the flexural rigidity to be quantified empirically. Due to their empirical nature, these design rules can only be applied within the bounds of the tests from which they were derived. Furthermore, as these design rules follow a full-interaction analysis, the slip between the reinforcement and adjacent concrete was not considered and the method does not cope with the discrete rotation of the cracks; that is, the deflection associated with crack widening was not directly considered. As an alternative, partial-interaction mechanics-based methods can be used. In this study, a mechanics-based approach for quantifying the deflection of adhesively plated RC beams was presented. The approach took into account the slip between the reinforcement and adjacent concrete, the formation and widening of flexural cracks, and the intermediate crack debonding mechanism of the externally bonded plate. The deflection from the mechanics-based approach was determined by considering the discrete rotation of individual cracks and the curvature of uncracked regions of the beam. The deflection results derived from the mechanics-based approach were compared with the experimental results of seven adhesively plated CFRP RC beams bonded to their tension face and a significant correlation between the results was observed. The mechanics-based approach does not require any components on the member level to be quantified empirically; thus, it could be useful in predicting the deflection of adhesively plated RC beams with new types of reinforcement material

Effect of elevated temperature to radiation shielding of ultra-high performance concrete with silica sand or magnetite

The high density and strength of ultra-high performance concrete (UHPC) makes it suitable for radiation shielding, however, the deterioration of radiation shielding properties due to exposure to elevated temperature is a major concern. Hence this paper presents a study on the radiation shielding properties of UHPC after exposure to elevated temperature. It was found that the half-value layer and tenth value layer of both types of UHPC tested had increased by 76–82%, which was attributed to the excessive spalling and cracking that occurred. Magnetite was found to be slightly better than silica sand for radiation shielding

Evaluation of Some Composite Paint Coatings’ Appearance Quality Using Fractal Dimension

Composite materials are characterized by multiple layers, which leads to a complexity in the design in order to ensure the effective operation of the constituent elements. This article provides information on the use of fractal dimension in assessing the quality of the appearance of paint coatings. The scientific originality of the article lies in the establishment of a correlation between the surface roughness of coatings, the quality grade of their appearance and fractal dimension. As a result, a model of the length of the coating surface profile, with the fractal dimension D, was proposed. The practical significance lies in the proposal to evaluate the quality of the surface of paint and varnish coatings in terms of fractal dimension. An increase in the surface roughness of the coating, a decrease in the appearance quality grade and an increase in the fractal dimension have been observed. Numerical values of the index of the fractal dimension of the coating surface profile, which depended on the porosity of the substrate, have been obtained. The influence of the filling of the paint composition on the quality of the appearance of the coatings has been estimated. It has been revealed that there was an increase in the surface tension of the paint composition, a decrease in the quality of the appearance of the resulting coating and an increase in the roughness and fractal dimension of the coating surface. The influence of the method of applying the paint composition and the preparation of the base surface on the quality of the appearance of the coatings are considered. The results obtained can be applied in various types of production to improve the quality of paint coatings