Research on Engineering Structures and Materials

643-658

Authors: Lemiye Atabek Savaş

ß-strontium hydrogen phosphate nanosheets (SHPs) with a thickness range of 35-50 nm were synthesized by hydrothermal method using strontium nitrate (Sr(NO3)2) and diammonium hydrogen phosphate ((NH4)2HPO4) as reagents. Polypropylene (PP)/SHP nanocomposites were prepared using melt blending technique with different filler concentrations ranging from 1 wt.% to 7 wt.%. Composites were characterized primarily by tensile test, flexural test, thermogravimetric analyses and ball-on-disc sliding wear test. Experimental results revealed that the inclusion of nanosheets into PP improved the thermal stability of the composites. In addition, the tensile and flexural properties of the composites improved with SHP loading. A maximum increment of 6.0 % in tensile strength compared to pure PP was observed at 7 wt.% SHP concentration, and flexural strength of the composites was found to be higher than that of the pure polymer at each filler concentration. However, an increase was observed in the friction coefficient and wear rates of the composites due to increased hardness and rigidity of the matrix with the addition of SHP, which produced micro-cutting and micro-plowing actions that caused increased abrasive wear of the composites.

675-694

Authors: Nasir Mohammed Tahir, Adamu Umar Alhaji, Ibrahim Abdullahi

Finite Element Method such as Abaqus software is increasingly used to analyze structures such as the Unmanned Aerial Vehicle Wing. Unmanned Aerial Vehicle is usually fabricated using synthetic materials such as Glass fibers, Carbon fibers and Kevlar. The problems with the synthetic fibers are environmental pollution during processing, energy consumption during processing and cost of production. Natural fibres can be used as replacement for synthetic fibers due to their comparable physical and mechanical properties. The research involves the simulation of an Unmanned Aerial Vehicle wing made from 5% Cold Alkaline treated 5% SterculiaSetigeraDelile fiber (SSD) at 0-degree orientation and 7.5% PterocarpusErinaceus (PTE) Wood dust Epoxy composite using Abaqus software. The wing was subjected to aerodynamic wing loading from 167.57N to 895N (3kg to 16kg). The result showed that the wing produced using the Novel material could withstand the most critical flight load distribution in conformation with Federal Aviation Regulation (FAR) part 23 Airworthiness standards with an ultimate design load of 5.7. At the point of failure the wing could withstand an Ultimate load factor of 20.26. Structural physical testing was performed for a wing loading of 167.75N to 335.50N (3kg to 6kg). The wing successfully resisted the critical in-flight loading confirming the simulation result. The Novel material of lower density (1.093g/cm3) could withstand the wing loading requirement making it suitable for the UAV wing application.

707-720

Authors: Prem Kumar V, Vasugi V

The increase in population promotes the construction industry to exploit the conventional building materials. This phenomenon leads to use of alternative building materials in the construction field. One of the effective natural materials is bamboo. In this paper, the Bamboo Fibre (BF) is used as an additive in the mortar at various percentages (1% to 4%) and Bamboo Stem Ash (BSA) is used as an alternative binder material to replace the cement at different proportions (2.5% to 10%). To increase the property of mortars, Styrene butadiene rubber (SBR) is used a super plasticizer from 0.5% to 2%. Due to high raising demand of river sand, Copper slag (CS) is used partially to replace the fine aggregate at constant percentage (50%) for all the mix proportion. W/B ratio is proportioned from 0.35 to 0.5 at different level. The design of experiment is conducted through Taguchi’s design and the experimental values are validated by Artificial Neural Network (ANN) tool for obtaining the predicted results with respect to dry density, water absorption, compressive strength and flexural strength. The experimental investigation proved that BF and BSA have a potential sign to be used as an alternative sustainable building material. From the comparative analysis of experimental results with ANN, it is revealed that the mortars show an acceptable prediction of physical and strength properties with a maximum error of 8.11%.

735-749

Authors: Olatunji Oladimeji Ojo, Gbadebo Samuel John

The weldability of the interlocked-end friction stir welding (IFSW) of aluminum plates was studied via the use of single and double-sided welding procedures. The abutting ends of the Al plates were milled into equidistant slots (with 5 mm rise and 10 mm span) and an interlocked/meshed end profile was formed when two slotted plates were brought together. The friction stir welding of the interlocked end of the plates was carried out at different tool rotational (700 – 1120 rpm) and traverse (21 – 63 mm/min) speeds while the structure, tensile strength, and fracture behaviors of the resultant welds were examined. The results showed the presence of flow-induced defects in the welds irrespective of the adopted welding procedure. Relative to the single-sided welds, the severity of the weld defect was significantly reduced in the double-sided welds due to dual material plasticization, material consolidation, and twofold recrystallization advantages. Improved tensile strength (from 39.6 to 69.1 MPa), reduced area fraction of flow-induced defect, and a large area with ductile features are obtained in the double-sided IFSW weld. A double-sided welding procedure is recommended for the interlocked-end friction stir welding process.

773-798

Authors: Tanvi Saxena, V.K. Chawla

Nano-fillers are bringing impeccable development in the area of materials science and natural fibers reinforced composites. In this study, a composite consisting of banana-carbon fiber reinforced epoxy matrix filled with 1%, 3%, and 5% weight percentage of nano-clay particles (NC) and carrying a transverse load is investigated for its mechanical and elastic properties. Nano-clay layer with interphase are arranged in layers called nano-clay platelets. The elastic properties such as longitudinal elastic modulus, transverse elastic modulus, in-plane Poisson’s ratio, in-plane and out-of-plane shear modulus for the proposed composite are calculated by using different analytical models namely, Mori-Tanaka, Bridging, Generalized Self-Consistent, and Modified Halpin-Tsai model. The strength and deformation of the proposed composite are analyzed by using the ANSYS APDL application. The proposed composite is modeled using two layers of banana fibers, two layers of carbon fiber, and one layer of nano-clay platelet. The fibers and nano-clay platelet are arranged in a specific sequence of banana fiber at 900, carbon fiber at 00, nano-clay platelet at 900, carbon fiber at 00, and banana fiber at 900. The proposed composite reinforced with 3% nano-clay is showing the least deformation as compared to 1% and 5% reinforcement. It is also observed that the modified Halpin-Tsai model outperforms all the other models as it is yielding the most effective elastic properties for the proposed composite and Mori-Tanaka model is found to be the least effective model for the calculation of elastic features of the proposed composite. Additionally, the hybridization effect for the composite is also calculated to analyze the tensile failure strain characteristics for banana and carbon fibers in the hybrid composite.

811-834

Authors: Altin Bidaj, Huseyin Bilgin, Marjo Hysenlliu, Irakli Premti, Rrapo Ormeni

A prolonged earthquake series hit the regions of Albania on September 21 and November 26, 2019, causing loos of live and extensive damage to the civilian structures. The main aim of this study is to investigate the structural and earthquake response of a template design, commonly encountered in the region, which was seriously damaged by the 2019 Durres/Albania earthquake. A 3D mathematical model of the entire structure was prepared, implementing macro-modeling approach to simulate its response under seismic shakings. Inherent material properties of its constituents were determined experimentally and adopted for the analytical model. Initially, an eigenvalue analysis was deployed to identify the dominant vibrations modes of the structure. Then, pushover analyses were performed to assess the earthquake response of the template designed structure, and possible failure mechanisms were examined. Finally, the obtained results from the software were compared with the real-life damage experienced by the building. In the end, it was observed that the analytical model proved to accurately estimate the earthquake behavior exhibited by the structure during the seismic shaking.

853-860

Authors: Om V. Vaidya, Kapil Malviya, Yuvaraj L. Bhirud

In today’s world, renovation and demolition is very common. This creates an aggregate waste. One can recycle this waste. Most of the waste that is generated from demolition of structures is dumped in landfills to reclaim land. These create a waste which contain concrete, bricks and other construction material which is of no use. By gathering all these waste and recycled it. The recycled concrete aggregate is created. Transport costs is very high that’s make it even worse. Therefore, recycling of RCA (Recycled Concrete Aggregate) is eco-friendly, which reduces the harvesting of Natural concrete and that aggregate might be used for the production of concrete for new construction. Recycled Aggregates Concrete uses demolition concrete and burned clay masonry structures as aggregate. In this research work the demolition waste is used in concrete and the properties were discussed using Compressive strength test, Flexural strength test, Split tensile test with 0, 30, 60 and 100 percent RAC.

885-904

Authors: Mahesh V. Raut

The production of fly ash is mounting steadily every year all over the globe, but the rate of recovery is insufficient compared to its production. The disposal of fly ash is becoming more and more difficult in India. Reusing fly ash for some valuable uses is one of the most convenient solutions to this problem. As a result, the present study has focused on the use of high volume fine grain fly ash as a partial alternative material for cement and sand with a low volume fraction of glass fiber. Glass fiber reinforced concrete mixtures consisting of up to 40% replacement of cement and sand by fly ash were produced for making sustainable concrete. The experimental work was carried out by preparing diverse mixes with a 0.40 water-cement ratio and analyzing the fresh as well as hardened properties of mixes. The experimental results reveal that the separate and combined replacement of cement and sand by fly ash together with glass fiber, enhance the durability and strength of concrete. When combining 20% of cement and 40% of sand replaced by fly ash together with glass fiber, better result was observed than all other mixes. The compressive strength, electrical resistivity (ER), and ultrasonic pulse velocity (UPV) increased by 36.33%, 65.82%, and 7.25% over control mix (C0-0). This discovery is very useful for making dense, durable and sustainable concrete by using proposed mixes.

431-445

Authors: K R Yellu Kumar, Adnan Qayoum, Shahid Saleem, Fasil Qayoom Mir

The current study involves a computational investigation on the cooling of the combustion chamber liners in a gas turbine engine. Effusion cooling is a high-efficiency, lightweight and low-cost cooling system widely used in combustion chamber liners nowadays. The effect of blowing ratio and effusion hole injection angle on adiabatic effectiveness is investigated. The simulations are carried using COMSOL Multiphysics 5.4 with the standard k- ε turbulence model. A 3D computational model consisting of mainstream duct, effusion plate and effusion holes has been incorporated for the analysis. The blowing ratios used in the study are 0.25, 0.5, 1, 1.25 and 1.5 at constant density ratio of 1.0 for different injection angles of 30° and 60°. The simulation results show a strong dependence of adiabatic effectiveness on the blowing ratios. For low blowing ratios the adiabatic effectiveness in effusion hole region is high on account of coolant being attached to the surface. On the contrary, for high blowing ratios the adiabatic effectiveness is low near the effusion holes region. In the downstream region of effusion holes the adiabatic effectiveness raises for high blowing ratios. In addition, it has been observed that injection angle of 30o provides better adiabatic effectiveness compared to injection angle of 60o. The velocity and temperature profiles are investigated to demonstrate the behavior of coolant flow on the effusion surface and the influence on adiabatic effectiveness. This study concludes that the proper selection of blowing ratio and injection angle improves combustion chamber’s efficiency and lifetime.

463-490

Authors: Nitin Kumar, Michele Barbato, Erika L. Rengifo-López, Fabio Matta

Finite element (FE) simplified micro-modeling techniques are commonly used to investigate and predict the mechanical behavior of masonry structures because they provide a good compromise between accuracy and computational cost. These FE techniques generally discretize masonry structural elements into expanded masonry units and zero-thickness interface joints of assumed known locations. These joints correspond to actual masonry joints and to preferential cracking surfaces, which are often placed vertically in the middle of the expanded masonry units to simulate the cracking mechanisms that are typically observed in masonry bricks and blocks. Three different versions of simplified micro-models (SMMs) are widely used in the literature to model the response of masonry walls and assemblies: SMMs with rigid, elastic, and elasto-plastic constitutive models for the expanded masonry units. All SMMs are based on the hypothesis that the masonry inelastic behavior and cracking are concentrated along the pre-defined zero-thickness interface joints. The hypothesis is often satisfied for ordinary masonry, in which masonry units are generally stronger than the masonry joints, i.e., mortar and unit-mortar interface. However, this hypothesis is not always satisfied for historical masonry with units of irregular shapes or for earth block masonry, in which masonry units and masonry joint can have similar mechanical properties. This paper highlights the capabilities and limitations of SMM techniques by comparing the experimentally-measured and numerically-simulated response of ordinary and earth block masonry walls, for which well-documented experimental results are available in the literature. It is found that SMMs can properly reproduce the mechanical behavior of masonry when the masonry units are significantly stronger than the masonry joints; however, SMMs produce poor estimates of the mechanical response when this hypothesis is not satisfied. This finding highlights the need to develop more general FE models to investigate the mechanical behavior of different masonry materials and construction techniques, as well as to identify the parameters controlling the cracking patterns and the conditions under which SMM techniques can be accurately use.

519-533

Authors: Megha Bhatt, Sandip A. Vasanwala

The 3rd revision of IS: 4998 i.e. 2015 edition adopted a limit state method of design for RC chimney and gave a new model of stress-strain relationship for concrete and steel. RC chimneys are tall cantilever columns having thin-walled hollow circular sections and subjected to axial compression resulting from self-weight and bending moment resulting from lateral forces. It has been seen that there are many disparities between the stress-strain relationship of these materials adopted by IS: 4998 – 2015 and other well-established design standards. This paper compares and discusses these disparities in terms of strength, ductility factor and energy absorption with the help of plotted moment-curvature charts. For the comparison, design recommendations of IS: 4998 – 2015, CICIND 2011, ACI: 307 – 08 are used. Moment-curvature curves are plotted using the major two conditions of the section i.e. yielding of tension reinforcement and crushing of concrete in compression. It is obtained from the study that CICIND 2011 gives higher results for all parameters, namely strength, ductility factor and energy absorption.

553-567

Authors: Afreen Nissar, M. Hanief, Fasil Qayoom Mir

Used engine oil is a high pollutant material as it contains extremely toxic contaminants accumulated during operation. These contaminants if disposed improperly can not only cause extensive damage to the environment but also affect all living organisms. To tackle this rising problem the engine oil can be recycled by recovery of its base oil and reused for various purposes. Since the cost of recycling is comparatively much lower than production from crude oil, so recycling can prove to be a preferable alternative source as crude oil reserves are getting depleted. In this research study, SAE 5W30 was collected from the vehicle where it had been used for about 3000 miles operation and the collected oil was then subjected to various recycling methods. The recycled oils obtained undergo various tests for quality check comparison by Rheometer, FTIR Spectrometer, Oil Densitometer and Flash Point Tester. From the results obtained it was clearly observed that the acid/clay treatment method fetched superlative results. The degree of viscosity reduction (%) in acid/clay treatment method was found to be 95.077% which was significantly greater than other methods. Also, different engine oil samples were analyzed and compared for contamination by FTIR spectroscopy which can assist in condition monitoring of the vehicle engine.

583-602

Authors: P.N. Ojha, Pranay Singh, Brijesh Singh, Abhishek Singh, Piyush Mittal

With the increase in strength, concrete explodes spontaneously at failure creating a serious safety hazard. Researchers are actively looking for methods to arrest the cracks in concrete and design a higher strength concrete that fails in a more ductile fashion. Fiber-reinforced concrete has emerged as one of the solutions to this problem. This paper presents findings from the experimental investigation conducted to compare the fracture behavior of plain and fiber-reinforced high strength concrete of varying compressive strength. Six different concrete mixes were prepared with w/b ratios of 0.47, 0.36, and 0.20 resulting in average compressive strength of 36, 52, and 92 MPa. Each mix consists of two variations, first without fiber and second with 1% of steel fiber by volume. The mixes were tested for their strength and fracture Behavior using various standard codes and recommendations. From the Load-deflection and Load-CMOD (Crack Mouth Opening Displacement) curves obtained from the study, Fracture parameters like Fracture energy, Stress intensity factor, energy release rate, and Characteristic length is evaluated and compared for plain and Steel fiber reinforced concrete. It was found that adding steel fiber significantly improves the fracture properties of the concrete of different compressive strengths. By adding 1% of steel fiber in the high-strength concrete, the average fracture energy increased by 850%, 770%, and 450% respectively for the concrete with compressive strength of 36, 52, and 92 MPa. Other parameters also show a very significant improvement suggesting fiber reinforcement as a suitable choice to prevent brittle failure and increase the fracture performance of high strength concrete.

615-632

Authors: Badrinarayan Rath

Nowadays road construction is rapidly increasing on-demand to meet several medium and long terms development programs. A huge amount of natural resources, types of machinery and fuels are used in road construction. Using material resources and fuel an efficient manner, reducing in emission of greenhouse gases and controlling various impacts on the environment are important tasks in the road construction industry. In the present research, several environmental impacts related to the construction of asphalt paved highways in Ethiopia have been determined using the Life Cycle Assessment Approach for common pavement materials and construction activities. A deep focus has been given towards the extraction and processing of sand and gravel for preparation of base and sub-base; transportation of these input raw materials; consumption of fuels by various road construction machinery; direct or indirect emissions of carbon dioxide and other pollutants to atmosphere etc. Various suitable methods have been used to calculate the impacts of raw materials, fuel and machinery on various categories such as global warming potential, ozone depletion potential, terrestrial acidification potential, freshwater eutrophication, freshwater ecotoxicity etc. From the investigation, it has been suggested to use recycled materials for substituting gravel as base or sub-base materials and biodiesel for substituting diesel in the transportation trucks and dumpers. These types of new recycled materials may greatly help in assisting the evaluation of sustainable pavement construction. The present case study may help for potential changes in asphalt pavement construction to improve environmental sustainability.

205-222

Authors: Michael Kanisuru Adeyeri, Olatunji Oladimeji Ojo, Adefemi Oluseye Adelusi

This study compares and optimizes the friction stir clinched and friction stir spot welded hybrid aluminum/acrylonitrile butadiene styrene polymer (Al/ABS) joints. The mechanical and fracture behaviors of the respective hybrid joints were investigated. The results show that the friction stir spot welded Al/ABS joint exhibited a higher tensile-shear failure load. The presence of higher deformation (protrusion-aided) and deeper tool profile-induced hole (stress raiser) in the friction stir clinched Al/ABS joint impaired the loadbearing resistance of the joint. The optimum tensile-shear failure loads of the friction stir spot welded, and friction stir clinched Al/ABS joints are 932 and 509 N respectively. Three fracture modes, namely unbuttoning, circumferential-partial Al in-polymer shearing, and mid-nugget shearing modes, ensue in both joint categories. Protrusion-aided deformation is not desirable for the improved performance of the hybrid Al/ABS joint. Friction stir spot welding is thus recommended for the fabrication of hybrid metal/polymer.

233-251

Authors: P. N. Ojha, Brijesh Singh, Shivam Prakash, Pranay Singh, Manish K. Mandre, Suresh Kumar

One of the biggest advantages of Roller Compacted Concrete is faster and economic construction along with lesser heat generation. It is primarily used in mass concrete work like in Pavements, Ports and Dams. In this study the properties of Roller Compacted Concrete such as Vee-Bee density, Vee-Bee time, initial setting time, final setting time and compressive strength are studied for twelve mixes prepared using two types of fly ash sources, three cement sources and three admixture types. Furthermore, on one of the mixes with the least cement to fly ash ratio mechanical and thermal property related tests were performed. These tests include split tensile strength, direct tensile strength, modulus of elasticity, Poisson’s ratio, apparent cohesion, angle of internal friction, specific heat of concrete by Transient Plane Source (TPS) method and Coefficient of Thermal expansion of Concrete. From the study it was found that compressive strength at 365 days is nearly two times that of 28 days. Also, there is negligible effect of adding admixture on compressive strength of roller compacted concrete. Current study shows that finer the fly ash, higher the compressive strength at later stage. The study on mechanical and thermal properties of Roller Compacted Concrete indicates that results are in line with Indian Standard Specification and Internationally reported values.

265-281

Authors: P. N. Ojha, Abhishek Singh, Brijesh Singh, Vikas Patel

Concrete is the most commonly used construction material across the globe. In view of achieving sustainable development, the use of blended cements is becoming more prominent nowadays. Many research studies are being carried out across the globe on addition of different additives to enhance the properties of cement and concrete which also includes different types of fibrous materials. In this study, the effect of addition of glass microfiber on physical and chemical properties of PPC was studied for 0.2%, 0.4% and 1.0% by weight of cement. Mechanical properties such as compressive strength, flexural strength, modulus of elasticity, split tensile strength and drying shrinkage of concrete made with PPC cement with and without glass microfiber at water to cement ratio of 0.50 were studied. Durability properties such as RCPT and air permeability were also evaluated. For study at elevated temperatures, concrete samples were exposed to temperatures of 200OC and 600OC for duration of 1 hour. From the experimental investigation carried out, compressive strength was observed to improve by 13.6 % for PPC containing glass microfiber in comparison to control PPC. Reduction in cracks due to plastic shrinkage of concrete was observed on addition of glass micro fibre in PPC. Drying shrinkage of concrete was observed to decrease on addition of glass micro fibre in PPC. Other mechanical and durability properties of concrete made with PPC with and without glass micro fibre were observed to be comparable. No significant improvement in mechanical properties due to addition of glass micro fibres was observed upon exposure of concrete to elevated temperatures.

307-336

Authors: Abiodun Kilani, Christopher Fapohunda, Oluwatobi Adeleke, Charity Metiboba

Wastes generation and emission of greenhouse gases are the major concerns of the contemporary world. Concrete’s cements companies in the globe are producing up to 2.8 billion tons of cements annually. This contributed to the emission of anthropogenic substances into the atmosphere which destroys the ozone layers. The incessant disposal of these agricultural wastes has detrimental effect on the environmental and human health. Thus, utilizing these wastes as secondary resources in concrete is a reasonable consideration in sustainable waste management in the circular economy. The use of agricultural wastes in concrete production has been gaining attraction in recent years, however, their effectiveness and performance in concrete need evaluation. This study presents an overview of the effects of some agricultural wastes: Bagasse, Coconut shell, Cotton, Oil palm and Hemp fibers on concrete and composite’s mechanical properties. As reviewed, Sugar-Cane Bagasse Ash (SCBA) and Coconut Shell Ash (CSA) are rich in cementitious (pozzolanic) properties (SiO2, Fe2O3 and Al2O3) for cement production up to 70%. Sugar-cane bagasse and oil palm-fiber ashes improved concrete workability. SCBA and CSA highly increased the concrete compressive strengths. The concrete tensile strengths were increased up to 97% with the inclusion of cotton and bagasse ashes. The SCBA, hemp-fiber and treated oil palm - fiber ash increased the concrete and composite’s flexural strengths up to 11.3%, 26.2% and 50.7% respectively. In conclusion, the output of this review will supply full data of the research gaps yet to cover on the use of agro-wastes in concrete for future investigations.

359-370

Authors: Laxmi M Ramdas, M. Helen Santhi G. Malathi

Dampers are being used in the buildings as one of the control mechanisms to bring down the vibration due to lateral loads like earthquakes. Different types of dampers such as viscous damper, friction damper, tuned mass damper, hybrid damper, etc have gained importance in the recent past in mitigating the undesirable effects of earthquakes. The behavior of damper installed buildings during earthquakes depends on the arrangement as well as the number of dampers also. In this study, fluid viscous damper (FVD) is provided in a G+19 storey high rise RC building to reduce the vibration due to earthquake effects. IS 1893:2016 code based methods are adopted to determine the seismic responses such as lateral displacement, drift, base shear and energy dissipation of the building with and without damper using ETABS software version 2018. The main focus of this investigation is to obtain a maximum benefit of using FVD considering the different arrangement and number of dampers in the building using PYTHON on the basis of drift and energy dissipation criteria. Out of 28 building models, models 4, 27 and 28 experienced drift more than the permissible limit (0.004) as specified in IS 1893:2016. The energy dissipation capacity of the buildings with dampers varies between 1306 and 2091 kN-m for the different models under study. The program suggests the positions 2, 22, 14, 17, 5, 11 with 80 numbers of dampers for the building and recommends the position 2 for the maximum benefit in terms of drift, energy dissipation and cost.

385-402

Authors: Hayri Baytan Ozmen, Naile Gül Tarakcı

For a more realistic approach, the effect of soil-structure interaction on the behavior of reinforced concrete buildings should not be neglected. In this study, nonlinear static pushover analysis is applied to the twenty-five 4-storey reinforced concrete frame buildings with different foundation types (raft and continuous foundation) and soils having different bearing coefficients. The foundation type and foundation sections were changed by keeping the reinforced concrete frame system constant. The stiffnesses of the models are observed to be significantly affected by the foundation dimensions and the soil bearing coefficient. Period increase up to 44% is observed per fixed base case. The lateral strength and damage distribution of buildings, seems to be less affected by foundation and soil conditions. The shear force in smaller columns becomes 8% to 24% more than anticipated by a fixed base model. The building displacement demand values with significant changes according to the fixed base case are observed. Amplifications around 40% seems to be possible per fixed base case. Additionally, an equation is established trying to answer the question of “How stiff the foundation should be for a given soil condition?”. If the allowable displacement increase per fixed base case and soil stiffness is known, dimensions of structural members of the foundation may be decided by given equation.

421-430

Authors: Lomesh Mahajan, Sariputt Bhagat

Supplementary materials (SM) for cement replacement became more feasible in the previous decade due to their pozzolanic strength and durability properties. The strength variation according to the age of the binding material is a critical subject for SM concrete. The time of water curing is critical in order to maintain the pozzolanic reaction in SM concrete, which assists in the development of strength in cementitious properties.In this study, the laboratory results of concrete specimens were assessed for various mix designs, and the obtained corresponding strengths were also predicted with ANN techniques. The difference between experimental and ANN predicted values was marginally low. Thus, the ANN model applicability emphasised the productive use in predicting the strength of supplementary materials like fly ash or any similar pozzalanic mineral admixture. This research proposes an ANN-based technique for predicting the strength of fly ash added SM concrete. Typical experimental data is used to build, train, and test the artificial neural network (ANN) model. With ANN and input parameters, a total of 324 distinct data points for SM concrete were utilised to estimate SM concrete strength. Various combinations of layers, number of neurons, and learning rate were examined during the training phase. When the root mean square error (RMSE) reached or remained below 0.001, the training was stopped, and the findings were verified using a test data set. With respect to the relative error provided for trained model data, the results achieved were typically below 10% for compressive strength and below 5% for split tensile strength. The ANN models predict concrete strength with excellent accuracy, and the findings show that utilising ANNs to predict concrete strength is both practicable and advantageous.

1-18

Authors: Özgür Demircan, Naser Rezaei Ansaroudi, Fatma Burcu Uzunoğlu

In this study, the effect of hexagonal boron nitride (hBN) and modified (carboxylic acid functionalized) multi-walled carbon nanotubes (MWCNTs-COOH) on tensile and flexural behaviour of 30% short glass fiber reinforced Polyamide 66 (PA 66/30SGF) is investigated. Initially, MWCNTs-COOH, hBN and MWCNTs-COOH/hBN are mechanically mixed with PA 66/30SGF granules in ethanol and stirred via a magnetic stirrer for one hour. After ethanol evaporates, MWCNTs-COOH, hBN and MWCNTs-COOH/hBN integrated granules are conditioned in an oven and the obtained granules are transferred to the plastic injection moulding machine for the fabrication process of specimens. Thus five types of specimens are produced; and their mechanical behaviors are examined by Instron 5982 test machine. The test results show that elastic modulus and flexural properties of PA 66/30SGF are improved with the addition of MWCNTs-COOH, hBN and MWCNTs-COOH+hBN.

45-56

Authors: Anil Kumar, Surjit Angra, Arindam Kumar Chanda

A sandwich structure consists of three main parts i.e. the facing skins, the core and the adhesive. It acts in a way similar to that of the I- Beam. In this research, a sandwich structure has been designed with a regular hexagon honey-comb core made up of Kevlar® and face sheet of carbon fiber. The design has been modelled and the model has also been validated with the experimental and analytical method. Six different configurations of sandwich structures have been proposed. Out of these six, three configurations have the varying cell size i.e. 3.2 mm, 4 mm and 4.8 mm and the other three configurations have the varying panel width i.e. 40 mm, 45 mm and 50 mm keeping rest of the design parameters unchanged. Using ANSYS, analysis has been performed for all these six configurations and equivalent stiffness has been calculated. It has been observed that the honeycomb core cell size does not have a significant effect on the stiffness properties of a composite sandwich panel. The analysis also reveals that with the increased panel width the stiffness of composite panel increases significantly.

75-89

Authors: Emre Esener, Aysema Ünlü

The plastic behavior of a material can be represented by plasticity models. The ability of plasticity models to represent material behavior depends on their mathematical form, the assumptions they hold, and the sensitivity of the input parameters. Plasticity models are of great importance, especially in finite element analysis. While the mathematical forms of plasticity models are implemented in finite element analysis software, some coding-related inaccuracies may occur. Therefore, the capacity of the plasticity model to represent the plastic behavior of the material can be revealed more accurately by examining it analytically. After this verification, the choice of the plasticity model to be used in the finite element analysis can be realized with more accuracy and less time loss. In this direction, in this study, the capacity of plasticity models, which are frequently used today, to model the plastic behavior of anisotropic materials was evaluated. For this purpose, Hill48, Barlat89, Hu2003 and Poly6 plasticity models were analyzed analytically and TBF1050 3rd generation advanced high strength steel and 5XXX series aluminum alloy were used as materials. The predictive capacities of the plasticity models were evaluated with the yield locus and angular variations of anisotropy coefficient and yield stress ratios. As a result, it has been revealed that polynomial-based models can model the plasticity behavior of the material more accurately for both material groups.

101-115

Authors: Ashwini K, Srinivasa Rao P

The strength and durability properties of concrete using nano-silica and alccofine after exposed to higher temperatures were investigated in this study. Concrete with 3% nano-silica and 15% alccofine were prepared and water cured for 28 days. In an electric boogie furnace, concrete specimens with and without nano-silica and alccofine were heated to 400°C and 800°C for 4 hours. The specimens then were allowed to cool until they reached room temperature. The compressive strength test was used to determine strength, whereas the water absorption, porosity, and rapid chloride permeability tests were conducted to check durability properties. SEM images were used to examine the microstructure of concrete specimens at elevated temperatures. According to the test results, the strength and durability properties of concrete using nano-silica and alccofine deteriorated at high temperatures. At room temperature, concretes containing alccofine and nano silica performed better than control mixes. A severe loss in strength and a significant increase in charge pass, water absorption and porosity were observed at 800°C for concrete using alccofine and nano silica. The microstructural analysis using scanning electron microscopy methods also reported that the porosity increased with increase in temperature.

127-154

Authors: Gaurav D. Dhadse, Gangadhar Ramtekkar, Govardhan Bhatt

The finite element (FE) modeling of interface in Soil-Structure Interaction (SSI) problem is most important aspect from early days of modeling i.e. during 1960. The overall performance of the structure is completely influenced due to behavior of interface. Such as realistic interface modeling of SSI system subjected to lateral loads leads to appropriate evaluation of lateral sway and base shear stress. During recent times, many modifications have been done in interface modeling such as incorporation of slip and bonding effects. Also the interface joining variable degrees of freedom system (interface for solid to skeletal contact) has come into existence. Still the de-bonding behavior, interface non-linearity as well as modification in solid to skeletal contact has been unexplored in literatures. Hence there is necessity to develop a FE-SSI model and to study the influence of interface in SSI system considering unexplored features. In this paper, an attempt has been made to show the influence due to interface (including de-bonding and non-linearity) in FE modeling of SSI system using modified 5 noded zero thickness interface element. The performance of modified interface element is a novel contribution in present paper. The present study is limited to static loading conditions only. The effect of interface has been studied by determining bending moment, lateral sway, base shear stress and footing settlement in structure. The inclusion of modified interface has improved the performance of structure by reducing the base shear stress and allowing the sway. Also the true redistribution of bending moment has been observed after considering the modified interface.

179-203

Authors: Muhammed Mücahid Toprak, Ceyda Kök, Suha Orçun Mert

The importance of green energy has increased in recent years. Vehicles that don't run on fossil fuels and have zero CO2 emissions are on the agenda of many developed countries. Battery-based vehicles have long charge times and low range problems, making hydrogen-based fuel cell vehicles a good alternative candidate as a solution. Fuel cell system designs used in these vehicles is one of the most important subjects in the dawn of the renewable energy age. The present study compares different flow channel pattern designs for PEM fuel cells used in vehicles, all of which were designed and modeled as part of the study. Simulations were run on the three-dimensional flow channel designs to determine the most efficient patterns. Efficiency analyses were extended to include the membrane surfaces, where different properties of fuel flow channels, overall energy efficiency, and certain other parameters used in the PEM fuel cell systems were investigated. The study also includes comparison of the designed systems with fuel cell designs currently in commercial use. Finally, the effects of H2 and O2 concentrations used in the system were also investigated.