Browsing by Author "Kuttagola, I."

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Application of Taguchi's optimization techniques for enhancing the fracture characteristics and brittleness of self-compacting alkali-activated concrete
(Elsevier B.V., 2025) Kuttagola, I.; Prashanth, M.H.
Alkali-activated concrete has emerged as a promising material for energy-efficient construction, offering a technically viable and eco-efficient alternative that aligns with global sustainability goals. This study explores optimizing fracture properties in self-compacting alkali-activated concrete (SAAC) through controlled variations in maximum aggregate size (dmax) and fly ash. A systematic approach incorporating Taguchi's design of experiments (DOE) and ANOVA analysis was employed to identify optimal mix proportions that enhance fracture performance and ductility. The study employed the Weight-Compensated Work of Fracture Method (WWFM) based on curtailment of the tail of the P–? curve to determine the size-independent fracture energy (GF), enhancing the reliability of SAAC in structural applications. Additionally, the Two-Parameter Fracture Model (TPFM) evaluated the critical stress intensity factor (KsIc) and critical crack tip opening displacement (CTODc), while the MATLAB-based Box-Counting Dimension Method (BCDM) assessed the fractal dimension (D). The findings revealed a higher fracture performance with 0 % fly ash and 16 mm dmax (GF of 206.3 N/m and KsIc of 1.91 MPa?m), suitable for structural applications requiring maximum fracture energy and toughness. The study further tailored a higher ductility mix with 50 % fly ash and 16 mm dmax (CTODc of 0.032 mm and D of 1.144) offering a balanced solution for non-structural applications, providing sufficient strength with enhanced ductility. The closed-form predictive design (CPD) model enables the prediction of ft and KIc under a specified maximum fracture load, offering engineers a practical tool to optimize SAAC formulations by adjusting aggregate sizes and binder proportions for specific project needs. Regression models aligned strongly with experimental and existing literature results, affirming the reliability of predictive performance for future SAAC mix designs. © 2025 Elsevier Ltd
Development and performance evaluation of self-compacting lightweight alkali-activated concrete incorporating hydroton clay balls
(Elsevier Ltd, 2025) Kuttagola, I.; Prashanth, M.H.
Alkali-activated concrete has emerged as a promising alternative in construction due to its enhanced performance characteristics and reduced carbon footprint. This study introduces a novel category of self-compacting lightweight alkali-activated concrete using hydroton clay balls (lightweight expanded clay aggregate, LECA) as coarse aggregate and manufactured sand as fine aggregate. The research investigates the influence of fly ash content in the binder and maximum aggregate size (MAS) on the mechanical properties of the concrete mixes. Three series of mixes were developed with MAS varying at 10 mm, 12.5 mm, and 16 mm, and fly ash proportions at 0 %, 30 %, and 50 %. A novel pre-treatment method involving geopolymer slurry was employed to enhance the stability of LECA by mitigating water absorption, crucial for achieving self-compacting properties. The lightweight concrete mixes demonstrated excellent filling and passing abilities, adhering to EFNARC guidelines, with the mix L10FA50 (smallest MAS and highest fly ash) achieving the highest workability. Compared to the normal-weight mix N16G100, the mix L10FA50 recorded 17 % higher slump flow, 45 % better sieve segregation resistance, and 34 % faster V-Funnel flow times. Dry densities of lightweight mixes ranged from 1851 to 1943 kg/m³, about 19–20 % lower than normal-weight concretes. The pre-treated LECA enhanced the mechanical performance of lightweight mixes, achieving maximum compressive strengths of up to 49.17 MPa, splitting tensile strengths of 3.40 MPa, flexural strengths of 8.60 MPa, and fracture energy of 161.51 N/m, approximately 65 % of the normal-weight mixes. Higher strength gains were particularly notable with higher GGBFS content and larger MAS. The microstructural analysis confirmed dense morphologies with C-S-H and C-A-S-H gel formations, contributing to improved strength. This research establishes the feasibility and performance benefits of utilizing LECA in alkali-activated concrete formulations for sustainable construction practices with enhanced mechanical and microstructural properties. © 2025 Institution of Structural Engineers
Experimental study on shear reinforced and shear deficient RC beams subjected to preloading and wrapping with CFRP sheets
(Elsevier Ltd, 2023) Prashanth, M.H.; Manjunath, R.; Koppad, A.; B, B.; Kuttagola, I.
An experimental work has been carried out to study the shear reinforced and shear deficient RC beams which are subjected to preloading and wrapping with CFRP sheets. Shear reinforced beams were wrapped with CFRP sheets and subjected to 0% and 50% preloading. Shear deficient beams were wrapped with CFRP sheets and subjected to 0, 50% and 70% of preloading. CFRP wrapped beams of shear reinforced (A2, A3) and shear deficient (B2 B3 B4) show substantial improvement in ductility and an increased ultimate load carrying capacity when compared to respective control beams. Due to preloading, ductility remains same with the marginal decrease in ultimate load carrying capacity when compared to respective 0% preloaded beam specimens. CFRP wrapping is found to be very effective in arresting initiation and development of cracks with and without preloading. © 2023
Numerical investigation of the hybrid reinforced concrete beam using GFRP bars
(Institute of Physics, 2023) Kumar, A.; Prashanth, M.H.; Kuttagola, I.
The numerical study of the hybrid reinforced concrete beam using GFRP bars has been explored in this research. Finite element software ABAQUS had been used for numerical investigation. In the present research, the use of GFRP bars as a replacement to steel reinforcing bars for longitudinal reinforcement is attempted. Further, a RC beam by using GFRP as longitudinal reinforcement and steel rebars as transverse reinforcement is compared with the conventional steel reinforced concrete beam. The beams are tested for three-point bending using numerical simulation under displacement control. By performing the numerical modelling, load, strain and displacement data has been attained. Further, by using the output data, stress-strain curves of concrete, load versus strain variations in tension bars and load versus deflection curves are plotted. The stresses, deflections, strain developed in longitudinal bars, load carrying capacity, energy absorption are then calculated using the data and are compared. From the results it is observed that, the load carrying capacity decreases by 16% and the energy absorption increases by 29% when longitudinal steel bars are replaced by GFRP bars. Â© Published under licence by IOP Publishing Ltd.
Numerical study on the behavior of RC beams by using GFRP bars as an alternate to steel bars
(Elsevier Ltd, 2023) Kuttagola, I.; Prashanth, M.H.; Kumar, A.
The numerical study of the behavior of reinforced concrete beams by using Glass fiber reinforced polymer (GFRP) bars as an alternate to steel bars has been explored in this research. The numerical modelling of the beams is done using Finite element analysis (FEA) software ABAQUS. In the present study the beam with Glass fiber reinforced polymer (GFRP) bars as both longitudinal & transverse reinforcement is compared with conventional reinforced concrete beam. The numerical simulation is performed for three-point bending for displacement control. The results of load, strain and deflection data has been obtained from the numerical modelling. Stress versus strain curves, load versus strain curves and load versus deflection curves are plotted using the output data. The displacement, strain developed in longitudinal bars and stirrups, load carrying capacity, energy absorbed are then calculated using the data and are compared. From the results, it is observed that the Glass fiber reinforced polymer (GFRP) reinforced concrete beams have load carrying capacity par with conventional reinforced concrete beam. Further, Glass fiber reinforced polymer (GFRP) reinforced concrete beams have higher yield strains and experienced more energy absorption over conventional reinforced concrete beam. Â© 2023 Elsevier Ltd. All rights reserved.
Study on the effectiveness of prefabricated cage system reinforcement in columns
(Institute of Physics, 2023) Thejarathnam, T.; Prashanth, M.H.; Kuttagola, I.
The concrete is the primary vertical load bearing component in a reinforced concrete column whereas the steel cage provides additional vertical load carrying capacity along with the confinement of core concrete. The research paper will focus on the performance of Prefabricated Cage System (PCS) Reinforcement in square columns. Eight columns were casted and tested, out of which two are rebar reinforced columns and six are PCS reinforced columns. There were two test groups, each group containing one rebar column and three PCS columns. In this study work is done to compare the performance of a PCS reinforced column to a rebar reinforced column, in addition comparing PCS cages of differently sized grid openings. The objective is to theoretically, experimentally, and numerically investigate the PCS column for its load carrying capacity and displacement capacity. From the results it is observed that as the size of opening of a PCS reinforced column increase, the load carrying capacity increases as the concrete running through the openings can strengthen the connection. Hence to improve the effectiveness of the PCS columns the spacing of openings should be increased. Further, the stiffness and energy absorption are more in rebar reinforced column compared to all PCS columns. Â© Published under licence by IOP Publishing Ltd.