Research on Engineering Structures and Materials

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.