Browsing by Author "Pavan, G.S."

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Deconvolution of Earthquake Ground Motions for Dynamic Analysis of Masonry Gravity Dams
(Springer Science and Business Media Deutschland GmbH, 2024) Singhal, U.; Pavan, G.S.
The present study aims at deconvolution of earthquake ground motions pertaining to dynamic analysis of masonry gravity dams. Deconvolution is a process that can be used to remove the effects of these distortions and obtain the actual ground motion. Dynamic analysis of masonry gravity dams incorporating soil-structure interaction requires the application of earthquake motion to the base of the foundation. Soil strata up to a depth of three times the height of the dam is generally included in the dam analysis. Deconvolution procedure is performed in this study for different types of earthquake ground motions and different types of soil strata present beneath the dam. In order to perform deconvolution, frequency domain approach is considered. In this frequency domain approach, the recorded ground motion data is first transformed into the frequency domain using a Fast Fourier Transform (FFT). The response at dam-foundation interface is also transformed into the frequency domain, and the two spectra are divided point-by-point. This procedure is repeated until reasonable accuracy is achieved. The deconvolved signal is then transformed back into the time domain using the inverse Fourier transform. This study provides an overview of the deconvolution of seismic ground motion using a frequency domain approach and highlights its importance in seismic research and engineering applications. Also, the importance of performing deconvolution of ground motions is assessed with respect to different types of soil strata lying underneath the dam. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Detection and Visualization of Corroded Surfaces Using Machine Learning
(Springer Science and Business Media Deutschland GmbH, 2024) Shrivathsa, B.J.; Dhanya, R.; Meghana Nayak, D.; Pavan, G.S.
The use of artificial intelligence in asset management greatly assists the industry and structural health monitoring systems. Using machine learning techniques for asset inspections can increase safety, reduce access costs, provide objective classification, and improve digital asset management systems. The detection and visualization of corrosion from digital images present significant advantages like automation, access to remote locations, mitigation of risk of inspectors, cost savings, and detecting speed. This paper used deep learning convolutional neural networks to build simple corrosion detection models and used an extreme gradient boosting algorithm to visualize the corroded surfaces. A large dataset of 1900 images with corrosion and without corrosion was collected using web scraping techniques and labeled accordingly. Training a deep learning model requires massive and high-resolution image datasets and intensive image labeling to approach high-level accuracy. The results and findings will improve the development of deep learning models for detecting and visualizing specific features on corroded surfaces. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Determination of Effective Properties of Masonry Using FEA-Based Homogenization Approach
(Springer Science and Business Media Deutschland GmbH, 2024) Honnalli, S.; Pavan, G.S.
Masonry is a widely used construction method. Masonry is typically heterogeneous in nature, consisting of bricks and mortar joints with varying mechanical properties. Thus, masonry will behave like a composite material with orthotropic material characteristics. However, the material heterogeneity of masonry will be ignored in the analysis of masonry structures, assuming it is a homogeneous, isotropic element, which is not true and leads to incorrect assessment. Thus, it is necessary to predict the orthotropic properties of masonry for the accurate assessment of masonry structures. On the other hand, predicting such orthotropic characteristics of masonry becomes a complex task, due to the presence of material heterogeneity. Therefore, researchers adopted numerical homogenization methods to assess the orthotropic properties of masonry. In this study, the FEA-based homogenization method is proposed to predict the orthotropic properties of masonry. Toward this direction, a small periodic part called the repetitive unit cell (RUC) of the English bond masonry prism available in the literature study is considered and modeled in ABAQUS software for the homogenization process. The constituents of RUC are modeled as a continuum element with linear and isotropic behavior. A series of linear stress analyses of RUC has been conducted using six-far field unit strains. The effective orthotropic properties of masonry can be predicted using the stressâ€“strain relationship obtained from the linear stress analysis of masonry RUC. Finally, the results obtained from the numerical homogenization process are validated with the experimental results available in the literature study. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Determining elastic properties of CSEB masonry using FEA-based homogenization technique
(Elsevier Ltd, 2023) Shalini, S.; Honnalli, S.; Pavan, G.S.
The world today is embracing a sustainable approach in all sectors. The construction industry is grappling with the problem of minimizing energy consumption and lowering carbon emissions involved in the manufacture of construction materials. Soil blocks are an alternative to fired clay bricks. Soil bricks are inexpensive, recyclable, environmentally friendly, and provide better thermal comfort. However, masonry walls built with soil blocks have several drawbacks. They are bulky, have poor durability properties and their strength capacity reduces significantly when saturated due to rain. The remedy for this problem is a Cement Stabilized Earth Block (CSEB). An engineered mixture of soil-sand-cement-moisture compacted at predefined levels offers superior strength and durability properties. The percentage of cement added is minimal in comparison to the soil-sand mixture content. In this study, a numerical model to predict the elastic properties of masonry comprised of CSEB and soil–cement mortar is developed. Both the constituents, CSEBs, and soil–cement mortar have different elastic properties. The presence of bed joints and perpends lends orthotropic behavior to masonry. The present study considers the Finite element analysis (FEA)-based homogenization technique to predict the elastic properties of CSEB masonry. A small periodic part of masonry called a repetitive unit cell (RUC) is considered, which is representative of the block-mortar arrangement in masonry. The three-dimensional masonry RUC is modelled using FE-based ABAQUS-CAE software. A user-defined Python script is developed to apply PBCs (Periodic boundary conditions) to RUC. The six far-field unit strains are applied to the RUC model in three normal and three shear directions. Finally, volume-averaged stress components are computed to determine the elastic properties. The modulus of elasticity and Poisson's ratio of CSEB masonry along three directions are determined. The proposed approach is governed by mechanics and not by empirical relationships and provides satisfactory results. © 2023
EFG meshless-ANN approach for free vibration analysis of functionally graded material plates on elastic foundation in thermal environments
(Taylor and Francis Ltd., 2025) K P, A.; Swaminathan, K.; Hirannaiah, S.; Pavan, G.S.
This study focuses on free vibration analysis of functionally graded material (FGM) plates supported by Winkler–Pasternak elastic foundation in thermal environment using element-free Galerkin (EFG) meshless method. Plate kinematics depend on first-order shear deformation theory. Uniform, linear, and nonlinear temperature variations through the thickness direction are considered, along with the temperature-dependent material properties. The numerical outcomes obtained from EFG method are compared with those available in the published literature to validate the proposed method’s accuracy. An artificial neural network (ANN) model that can easily predict the natural frequencies of the plate is constructed from the EFG method outcomes. Further, the effect of foundation parameters, power law index, thickness ratio, temperature variations, and different boundary conditions are investigated; results show that these significantly influence the vibration response of FGM plates supported by the elastic foundation. Increasing the temperature of FGM plates supported by the Winkler–Pasternack foundation causes a decrease in the dimensionless fundamental natural frequency, and the uniform temperature influence is greater than that of linear and nonlinear temperature variation. The proposed EFG-ANN prediction model saves approximately 98.80% computation time when predicting the natural frequency with an accuracy of approximately 98.76% compared to that by EFG meshless method alone. © 2024 Taylor & Francis Group, LLC.
Insights into the influence of microstructure on strength and damage progression in carbon/carbon composites
(SAGE Publications Ltd, 2025) Vishnu, O.S.; Pavan, G.S.
Microstructural features influence the mechanical properties and damage progression in advanced materials like Carbon/Carbon (C/C) composites. This study proposes a finite element-based framework to analyze the damage mechanism in unidirectional C/C composites incorporating the effects of fiber arrangement, microstructural defects, and fiber-matrix interface. A 3D Representative Volume Element (RVE) is developed, which consists of carbon matrix, randomly distributed carbon fibers, and pores. The pores in the microstructure are modeled as ellipsoids of varying size, shape, and orientation. Separate stress-based failure criteria and fracture energy-based evolution laws are prescribed for fiber, matrix, and fiber-matrix interface. A user-defined material subroutine (UMAT) is developed in the finite element software Abaqus to implement the initiation and progression of damage in the composite constituents. The homogenized stress-strain response is computed under different loading conditions, namely longitudinal, transverse, in-plane shear, and out-of-plane shear loading. The variation of transverse tensile strength with porosity is also examined, highlighting the influence of pore volume fraction on the mechanical performance of the material. The proposed numerical model is validated through comparison with the Chamis analytical model and with numerical and experimental results from the literature. The proposed framework adopts detailed modeling strategies harnessing the power of computation and individual failure criterion-evolution laws for reliable simulation of damage and strength evaluation of composite materials, which are extensively used in advanced aerospace and engineering applications. © The Author(s) 2025
Interfacial behavior of cement stabilized rammed earth: Experimental and numerical study
(Elsevier Ltd, 2020) Pavan, G.S.; Ullas, S.N.; Nanjunda Rao, K.S.
Cement stabilised rammed earth (CSRE) is a modern earth construction technology witnessing renewed interest by researchers worldwide due to its improved strength and durability vis-a-vis un-stabilised rammed earth (URE). Rammed earth walls are predominantly subjected to compressive loading and occasionally to lateral loads. Strength and deformation ability of interface in rammed earth plays a vital role in case of in-plane lateral loads. The present study focuses on assessing the performance of interface layers in cement stabilized rammed earth elements. Triplet test is conducted on CSRE specimens under dry and saturated condition. Three types of bonding techniques are considered for the interface in CSRE triplets, namely, (i) formation of dents (ii) coating cement slurry across interfacial area (iii) combination of dents and slurry. The influence of stresses normal to the interface of CSRE triplet is also explored in this study. Further, a finite element simulation of the CSRE triplet test is performed. A finite element model of the CSRE triplet is developed by using ABAQUS software. Eight node brick elements are adopted to model the CSRE material and interface. Linear elastic material model is adopted for the CSRE material whereas a PPR-potential based cohesive model is adopted for the interface. Shear stress-displacement curve obtained from the finite element model and experiment are compared with each other and were found to be in reasonable agreement. © 2020 Elsevier Ltd
Isogeometric Analysis of Composite Sandwich Plates Using Equilibrium-Based Stress Recovery Procedure
(Springer Science and Business Media Deutschland GmbH, 2023) Chethan, J.; Pavan, G.S.
Composite sandwich plates consist of a core and face sheets on the top and bottom.Accurate determination of three-dimensional stress states in sandwich plates by numerical approach requires the adoption of 3D finite element (FE) modeling or FE modeling based on layer-wise theories.Though both these numerical approaches give accurate results, they are computationally expensive.This study introduces an equilibrium-based stress recovery approach for determining three-dimensional stress state in composite sandwich plates subjected to transverse loading.This numerical approach is a two-part process, with the initial step based on the concept adopted by layer-wise theories, and the second step is a post-processing procedure.For approximating the unknown field variables, this computational approach employs non-uniform rational B-splines (NURBS).NURBS functions offer the flexibility of a higher degree of inter-element continuity.The study has adopted numerical examples based on the bending of sandwich plates under a sinusoidal load and an evenly distributed load with different edge conditions.Results obtained were compared with the 3D FE method and layer-wise theories and were found to be accurate.In comparison to the 3D FE method and the layer-wise approach, the study reveals that the proposed strategy can provide correct findings with a substantially lesser number of degrees of freedom. Â© 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Micromechanical Analysis of Carbon/Carbon Composites with Pore Characterization
(Springer Science and Business Media Deutschland GmbH, 2025) Vishnu, O.S.; Paul, J.; Pavan, G.S.
In this study, the elastic properties of carbon/carbon (C/C) composite are computed by incorporating the presence of pores. Microstructure of C/C composites is analysed using scanning electron microscope (SEM) images. The pores inside the C/C composite are characterized based on area, shape and dimensions. Thirty-six SEM images are analysed. Based on this analysis, a three-dimensional RVE of C/C composite is constructed. The number of pores, their size and spatial distribution in the RVE is given by the analysis. Carbon fibres inside the representative volume element (RVE) are generated using the random sequential adsorption algorithm (RSA). Once the model is generated, periodic boundary conditions are imposed on the RVE model using Python script in Abaqus CAE. Effective elastic properties of C/C composites are computed using the finite element analysis (FEA)-based homogenization method. The effect of pore size distribution on the elastic properties of C/C composite can be understood from this study. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
Microstructure Characterization and Effective Elastic Properties of Carbon/Carbon Composites
(Springer Science and Business Media Deutschland GmbH, 2024) Vishnu, O.S.; Pavan, G.S.
In this research, the effective elastic properties of C/C composites are evaluated using FEA-based homogenization technique. The FEA-based homogenization procedure is carried out by generating a Representative Volume Element (RVE). The features in the microstructure are observed with the help of Scanning Electron Microscopy (SEM) images. A detailed study on the SEM images of C/C composites is carried out. The microstructure of C/C composite consists of carbon fibers and carbon matrix. The details obtained from the microstructure are used to generate the RVE of the C/C composite. Random Sequential Adsorption (RSA) algorithm is employed to insert the carbon fibers inside the RVE model. Periodic boundary conditions are imposed on the RVE model, and six different far-field strains are applied on the RVE. For each case of far-field strains, the effective response of the RVE model is evaluated. The effective elastic properties of C/C composites are obtained by combining the volume-averaged stresses of the RVE for each case of far-field strains. The results from the numerical study are compared with those from the Moriâ€“Tanaka method. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Modelling Interfacial Behaviour of Cement Stabilized Rammed Earth Using Cohesive Contact Approach
(Springer Science and Business Media Deutschland GmbH, 2023) Pavan Kumar Reddy, T.; Pavan, G.S.
A monolithic construction formed by compacting processed soil in progressive layers in a formwork is called a rammed earth wall. A lot of applications of using rammed earth walls for both load bearing and non-load bearing can be seen across the world and carbon content is low in this building material. The construction of rammed earth structures involves layered compaction, thus forming an interface between two layers. Modelling of interface plays an important role in the strength and durability of these structures. The interface is modelled using a cohesive contact approach and the response of the rammed earth triplet is obtained. The slope of load vs displacement curve of the rammed earth triplet is 81% accurate with the experimental slope and the peak load of the triplet is 82% accurate with the experimental peak load. Thus, the comparison of load versus displacement obtained from the finite element method with experimental data of load versus displacement yields almost similar results. Â© 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Multiscale Numerical Modeling of 2D C/C Composites Considering Pore Size Distribution
(American Society of Civil Engineers (ASCE), 2024) Vishnu, O.S.; Pavan, G.S.
This study proposes a multiscale numerical modeling procedure to evaluate the elastic properties of two-dimensional (2D) eight-harness satin woven carbon/carbon (C/C) composites. The multiscale modeling technique consists of analysis at the microlevel and mesolevel. In microscale analysis, a 3D representative volume element (RVE) of C/C composite with carbon fiber, pyrolytic carbon, and pores is considered. The microstructure of the C/C composite is analyzed using scanning electron microscope (SEM) images. Statistical characterization of pore distribution inside the C/C composite is performed, and different probability density functions are generated for pores' number, area, and aspect ratio inside the C/C composite. Carbon fibers and pores are inserted in the 3D RVE using the RSA algorithm. The size and shape of the pores inserted in 3D RVE are based on the probability density functions generated. Effective elastic properties of C/C composite at the microscale are computed by finite element analysis (FE) based homogenization and taken as input for the next level of homogenization. The RVE at mesoscale is modeled using the information from SEM images, and FE-based homogenization is performed to compute the effective elastic properties of 8HS woven C/C composite. The effective elastic properties obtained from the numerical study are validated with the results of the uniaxial tensile test performed on 2D C/C composite. The effect of fiber volume fraction, yarn volume fraction, and porosity on elastic properties of 2D 8HS woven C/C composite are also assessed and presented in this study. © 2024 American Society of Civil Engineers.
Multiscale numerical modeling of clay brick masonry under compressive loading
(Springer Science and Business Media Deutschland GmbH, 2024) Honnalli, S.; Vishnu, O.S.; Pavan, G.S.
Masonry is generally comprised of periodic arrangement of masonry unit bonded together with mortar. Masonry is a heterogenous material and exhibits orthotropic behavior. In this study, the elastic-inelastic behavior of brick masonry under compressive loading is predicted using Finite Element Analysis (FEA) based homogenization approach. A three-dimensional repetitive unit cell representing English bond brick masonry is adopted for the homogenization procedure. The proposed approach requires elastic properties, peak compressive and tensile stress, and strain at peak stress values of brick and mortar as the inputs. Material non-linearity in brick and mortar is modeled using concrete damage plasticity model present in ABAQUS software. Using the FEA-based homogenization approach, homogenized stress–strain response of brick masonry subjected to compressive loading (both, normal and parallel to bed joint) and shear loading are obtained. Failure of masonry due to progressive damage development in bricks and mortar joints when subjected to compressive loading is studied. A user-defined material (UMAT) code is developed based on homogenized stress–strain curves. This UMAT can be adopted as constitutive relationship for macro scale modeling of brick masonry using ABAQUS software. The performance of the UMAT is assessed by simulating compression test experiments performed on masonry assemblages found in the literature. The UMAT is found to be satisfactory in predicting the behavior of masonry under compression. © Springer Nature Switzerland AG 2024.
Numerical Modeling of Damage Behavior in Unidirectional Carbon/Carbon Composites
(Springer, 2025) Vishnu, O.S.; Pavan, G.S.
Carbon/carbon (C/C) composites are frequently employed in aerospace industries because of their outstanding mechanical properties at high temperatures. This study proposes a progressive damage development model for unidirectional C/C composites. C/C composite consists of carbon fibers and pyrolytic carbon matrix. A Representative Volume Element (RVE) incorporating the microstructural features is generated based on the Scanning Electron Microscopy (SEM) images of the C/C composite samples. The composite constituents, namely carbon fiber and pyrolytic carbon matrix, are modeled explicitly inside the RVE, and failure criteria are provided for the individual constituents. The damage model used in this study comprises damage initiation and evolution criteria. The carbon fibers are inserted inside the RVE using the Random Sequential Adsorption algorithm (RSA). The carbon fiber is modeled as a transversely isotropic material, and the damage initiation is based on the maximum stress criteria. The carbon matrix is considered as an isotropic material, and damage initiation inside the carbon matrix is based on modified von Mises stress criteria. The damage evolution criteria, which depend on the fracture energy of the material, are used to predict the post-peak behavior of the components following the onset of damage. The non-linear damage behavior of unidirectional C/C composite is studied under axial tensile loading conditions. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.
Numerical studies on modeling heterogeneity in elastic properties of 8HS woven C/C composites
(Taylor and Francis Ltd., 2025) Vishnu, O.S.; Pavan, G.S.; R, S.; Thomas, A.
The variation in fiber volume fraction and pores developed at the microscale during the manufacturing process is a source of heterogeneity in the elastic properties of woven Carbon/Carbon (C/C) composites. This study investigates the effect of heterogeneity on the elastic properties of Eight Harness Satin (8HS) woven C/C composites using a two-scale (micro–meso) finite element (FE) homogenization method. At the microscale, variations in fiber volume fraction and porosity are incorporated by generating 25 representative volume elements(RVEs) from the reconstructed CT scan images. The RVEs preserve the shape, size, orientation, and spatial distribution of pores that are present in the microstructure. The carbon fibers are virtually generated inside the 25 micro-RVEs using the random sequential adsorption (RSA) algorithm in accordance with the reconstructed microstructure of actual pores. At the mesoscale, the model incorporates warp and weft yarns embedded in a pyrolytic carbon matrix. Yarn heterogeneity is modeled by subdividing the meso RVE into smaller domains, each assigned elastic properties derived from the microscale RVEs. The degree of heterogeneity was varied using different combinations of the microscale RVEs to assign material properties. This approach effectively incorporates the randomness of the microstructure into the computation of the effective elastic properties of woven composites. The on and off-axis elastic properties of 8HS woven C/C composites are computed, and the results determined from the numerical study are compared with experimental tests conducted on 0° and 45° specimens. This study highlights the importance of fiber volume fraction and pores on material heterogeneity in accurately computing the elastic properties of 8HS woven C/C composites. © 2025 Taylor & Francis Group, LLC.
Pseudo-Dynamic Analysis of Gravity Masonry Dams
(Springer Science and Business Media Deutschland GmbH, 2024) Shalini, S.; Kumar, M.A.; Pavan, G.S.
According to USGS estimates, approximately 5 million earthquakes occur annually, of which 1 million are felt. In the north-eastern and north-western regions of India, where the Indo-Australian plate is subducted beneath the Eurasian plate, seismic activity is extremely high. In addition to the immediate damage, an earthquake can cause minor vulnerabilities that lead to future crises. Safety of important infrastructure like dams, bridges, tunnels, elevated structures, and nuclear power plants under earthquake ground motion is critical. In the past 50Â years, seismic analysis of dams has attracted considerable research interest. In this study, a pseudo-dynamic analysis of non-overflowing section of a masonry gravity dam is conducted. Invoking plane-strain condition, a 2D model of the dam is developed in Abaqus software. The dam is modeled using four node rectangular elements. The loads at various levels along the dam's height are computed for the fundamental, higher, and static modes. The effects of hydrodynamic forces acting on the dam are also incorporated. The loads are applied separately, and stress analysis is performed. Stress values are combined using the SRSS method, these stresses are compared to the material's strength properties, and the risk factor is evaluated. A comparison of the stresses obtained from FEM model and stresses obtained by considering beam idealization is also presented in this work. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.
Replacement of River Sand with Coal Bottom Ash as Fine Aggregate in Cement Mortar
(Springer Science and Business Media Deutschland GmbH, 2022) Wasnik, S.; Pavan, G.S.; Padhi, S.
River sand is used as fine aggregate in concrete and cement mortar. The rapid expansion in construction activity witnessed in the country over the last decade has led to an incessant demand for river sand. Hence river sand is being excessively mined at the riverbeds and is leading to fast depletion of the precious natural resource. This presses the need for exploration of alternative materials which can be adopted as fine aggregate by construction industry to build concrete and masonry buildings. One possible candidate is coal bottom ash. Coal-based thermal power plants produce tonnes of coal bottom ash along with fly ash during power generation. Coal bottom ash is coarse particles settled at the bottom of cooling towers. The coarse nature of coal bottom ash particles can be harnessed and explored. The present study focuses on utilization of coal bottom ash as fine aggregate in cement mortars. River sand is fully and partially replaced by coal bottom ash. Five different proportions of river sand being replaced with coal bottom ash are adopted, namely 0, 25, 50, 75 and 100%. Performance of replacement of river sand with coal bottom ash is assessed in terms of particle size distribution (PSD) curves, workability and mechanical properties. Sieve analysis and mortar flow table test are conducted to assess the PSD curves and workability. Compression tests are conducted on cement mortar cubes (with different proportion of coal bottom ash) to determine compressive strength. Further, compression test is conducted on cement mortar cylinders in a displacement-controlled universal testing machine (UTM) to obtain the stressâ€“strain curve and modulus of elasticity. The study found that river sand replaced with up to 50% coal bottom ash exhibited satisfactory performance as fine aggregate in cement mortar. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Static, free vibrational and buckling analysis of laminated composite beams using isogeometric collocation method
(Elsevier Ltd, 2022) Pavan, G.S.; Muppidi, H.; Dixit, J.
Isogeometric collocation (IGA-C) method is a computational approach to solve boundary value problems. In this method (IGA-C), the differential equations are solved in strong form instead of the weak form approach adopted by Galerkin based formulations. IGA-C method is computationally efficient in comparison to conventional finite element method and Galerkin-Isogeometric approaches. IGA-C method does not involve the process of assembling global stiffness matrix from element stiffness matrix. Another advantage of IGA-C is that it requires a single integration point per element irrespective of the order of Non-Uniform Rational B-Spline functions (NURBS) adopted. Isogeometric collocation has also been demonstrated as a stable, efficient and accurate higher order computational method for explicit problems. For a wider adoption of isogeometric collocation method, beam/plate/shell finite elements within the framework of IGA-C method need to be formulated. Owing to the extensive adoption of laminated composites in structural components, development of beam finite elements for laminated composite beams based on isogeometric collocation method will prove useful during analysis of composite structures. IGA-C method is proposed in this study for the static bending, free vibration and buckling analysis of laminated composite beams. Classical laminated plate theory (CLPT), first order shear deformation theory (FSDT) and higher order shear deformation theory (HSDT) are considered for all the three analyses. The computational approach proposed for laminated beam based on HSDT contains two Degrees of Freedom (DOF) per node. Computational approach for analysing laminated composite beams based on each of these kinematic theories and using IGA-C method is presented. Accuracy of the proposed computational approaches is checked by solving different numerical examples. Values of normalized transverse displacement, normalized stresses, normalized natural frequencies and normalized critical buckling loads are compared with results from the literature and are found to be accurate. © 2022 Elsevier Masson SAS
Strength and Durability Properties of Alkali-Activated Fly Ash Earth Bricks
(Springer Science and Business Media Deutschland GmbH, 2022) Vasavi, G.S.; Mourougane, R.; Pavan, G.S.
This study explores the strength and durability characteristics of alkali-activated fly ash earth bricks. Two kinds of bricks were produced, one set of bricks with the use of manufactured sand or M-sand and another set without M-sand. Alkali activator which is a combination of laboratory-grade sodium silicate and 10Â M sodium hydroxide in 1:1 mass ratio is used in the study. Soil classified as clayey sand with a clay content of 14% is selected for the project. The fly ash/soil ratio and alkali activator/fly ash ratios of 0.4 and 0.6, respectively, are employed in the current study. Activator was added to the soil and M-sand and fly ash mixture and mixed thoroughly. The moist mixture was then added into the brick-making machine and compacted into bricks of size 114Â mm Ã— 102Â mm Ã— 230Â mm. The bricks were subjected to ambient curing until the day of testing. Wet and dry compressive strength tests, complete saturation, flexure test, and split tensile test were conducted on the bricks. It was found that the dry compressive strength of the bricks is in the range of 8 to 10Â MPa, wet compressive strength is around 70% of dry compressive strength, water absorption is around 8â€“12%, and split tensile strength is in the range of 0.47â€“0.55Â MPa and with flexural strength of 0.85â€“1.01Â MPa. Â© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Strength and Durability Properties of Early Cement-Soil Mortar
(Springer Science and Business Media Deutschland GmbH, 2024) Teja, K.S.; Pavan, G.S.
Looking back at history can inspire new construction technologies and methodologies. Our ancestors used earth as a primary building material, and from prehistoric times, they adopted clever yet simple construction techniques. Mud, which is widely available locally, is a valuable material due to its flexibility in processing and energy efficiency. Mud has been used for construction in India and elsewhere for a long time, and even today, mud wall construction is common in rural parts of India. Although mud is prone to degradation from rain and wind, it is a reliable material with advantages such as affordability, abundance, and good fire resistance. For low-rise and low-cost buildings, mud remains a dependable material. Researchers have discovered methods to enhance mud's quality and durability through stabilization processes to overcome the disadvantages of pure mud construction. In this study, durability aspects of cement-sand-soil mortar are explored. Soil with varying ranges of clay content is considered. Different amounts of cement content are added to obtain different proportions of cement-sand-soil mortar. Durability aspects of mortar that are explored by conducting tests like workability, compressive strength, sulfate-resistance test, acid resistance test, drying shrinkage test, and water absorption test are determined for cement-soil mortar and compared with cement mortar. Â© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.