bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of technology and methods for detecting metal inclusions in composite materials
Authors: Kuznetsov A
Published: October 2020

In complex multilayer structures made from PCM, metal inclusions of small sizes (from 0.1 ÷ 0.2 to 15 mm) randomly distributed throughout the material (at depths up to 100 mm), are unacceptable for normal operation, as they can penetrate into the material structure of a finished product. This paper is aimed at developing a device that provides a small error in determining the coordinates of small-sized metal inclusions in PCM when they are detected in real conditions of production and operation. Some devices capable of detecting the content of small particles in fluids or capable of detecting metal objects in various environments are known. The disadvantages of these devices are that they can only detect magnetically active particles, or large objects–more than 3–6 mm, while the location accuracy is recorded with a big error, insufficient for the detection process of small metal inclusions in PCM–from 30 mm and higher. This determines the urgency of developing a device for detecting small metal inclusions in finished products from PCM and in the technological cycle of their production. In this paper, the basic principles of the developed device are described, a block diagram of the device is presented, including the configuration of the eddy current transducer and the main processing units of the signals coming from the transducer. As confirmation of the operation of the developed device, photos of experimental studies and their results are presented in the form of the obtained dependences of the value of metal inclusions on the depth of their occurrence, from which it can be seen that the error in determining the depth of small-sized metal inclusions by the developed device did not exceed 10% and unchanged for all small-sized metal inclusions.
New approaches to diagnostics of quality of structures from polymeric composite materials under force and shock impact using the analysis of temperature fields
Authors: Budadin O , Razin A , Aniskovich V , Kozelskaya S , Abramova E
Published: October 2020

A rheological mathematical model that describes the process of formation of internal heat sources in a polymer composite material during its force loading, based on the process of microdestruction formation and the formation of dynamic temperature fields on the surface of the structure during thermal control, has been developed. The methodology as well as software and hardware for computer thermal control and diagnostics of the technical condition of complex spatial structures from PCM based on recording information about dynamic temperature fields have been developed and implemented. A thermal method has been developed for the quality control of composite armored barriers made of aramid materials through the study of the processes of its interaction in real time with a damaging element (kinematic, deformation, wave, thermal processes), which allows to increase the reliability of the quality of diagnostics, increase testing efficiency, visibility and objectivity of the results.
Selecting main technical specifications of the data aquisition system to improve the accuracy of using the electric response parameters
Authors: Dann D D , Petrov M V , Fedotov P I
Published: October 2020

Based on the conducted experimental studies, the necessary parameters were selected to provide reliable testing of concrete defects. The measuring system must have: input sensitivity of the receiving electromagnetic channel of at least100 μV, the working frequency range of 1–120 kHz; the sampling frequency of 500 kHz, as well as a device that allows fast Fourier transform. The registration of the electrical response during an elastic impact should be made by a differential electric sensor, which allows measurements under conditions of external electromagnetic interference.
Measurement of composite material strain using correlation of ultrasonic images
Authors: Titov S A , Levin V M , Petronuk Y S , Morokov E S
Published: October 2020

This paper is devoted to the evaluation of composite materials and components using ultrasonic visualization of structural changes caused by the external force. It is proposed to measure the strain of a sample under load using digital correlation of images recorded by a scanning acoustic microscope. An algorithm for processing the spatio-temporal ultrasonic data is developed to measure the longitudinal and transverse strains versus the applied force. The four-layer carbon fiber-reinforced composites with alternating packing of fibers (90/45) are evaluated by the proposed method. The relationships between the strains and the applied force are obtained up to the destruction of the sample. It is shown that the maximal longitudinal and transverse strains achieved for the test sample are 1.2% and 0.3%, respectively.
Acoustic-electric non-destructive method to detect defects in dielectric materials
Authors: Bespal’ko A , Surzhikov A , Dann D , Pomishin E , Petrov M
Published: October 2020

The paper reveals the effect of imperfection of solid-state dielectric samples on the parameters of the electromagnetic response under exposure of the test object to deterministic acoustic impact. The patterns of changes in the parameters of electromagnetic signals with variations and an increased electric field vector with respect to the defect–sample contact are provided. It is shown that the amplitude-frequency parameters of the emitted electromagnetic signals are directly related to the acoustic impedance and conductivity of the contacting medium and defect. The amplitudes of the electromagnetic responses are found to correspond to the distribution of mechanical stresses arising in an imperfect system during acoustic pulse propagation in time and space determined through mathematical modeling. The paper presents data on changes in the electromagnetic signal parameters for model defects of an increased size in samples of similar type.
Fluid level sensors with metrological self-check function based on the concentration effect
Authors: Kalashnikov A A
Published: October 2020

This paper presents the results of the experiments on studying the properties of concentration elements, which were carried out in order to develop a new principle for measuring the level of conductive and non-conductive polar liquids, as applied to the operating conditions of nuclear and thermal power facilities. The paper includes the methods for increasing the level and stability of the useful signal of concentration elements and design solutions for creating the fluid level multi-electrode sensor.

Considering the current trends towards an increase in the number of measuring channels at NPP and TPP power units and the need to optimize metrological service, it is noteworthy that the concentration effect is considered not only in terms of a new principle for measuring the liquid level, but also implementation of metrological self-check of conductometric and capacitive fluid level sensors.
Development of the flight laboratory for research of aerodynamic surfaces deformation
Authors: Poroykov A Yu , Surkov D A , Ilina N S , Lebedev S V , Ul’yanov D V , Lapitsky K M , Shmatko E V
Published: October 2020

In-flight measurements are developing directions of aircraft testing. The practical implementation of these tests allows accelerating the development of new types of aircraft, the in-flight tests of serial samples, and their commissioning. Carrying out such tests is associated with high cost. In this paper the creation of a flight laboratory based on an unmanned vehicle is proposed. This will significantly reduce the cost of testing but in-flight conditions will be close to real tests. A system for recording experimental images during in-flight test was developed for conducting studies of deformations of aerodynamic surfaces. In this paper, the system based on single board computer is described; its main functions and features are considered. The results of laboratory tests of the developed system on a model of a deformable wing are presented.
Object orientation measurement system without zero drift
Authors: Poroykov A Yu , Lebedev S V , Kontsov R V , Sinitsyn A A , Zharenov I S
Published: October 2020

The need for zero drift and accurate object pose estimation is very common in today’s industry. Implementing optical measurement system allows to overcome certain problems, that are inherent to inertial navigation systems (INS). These problems include size and weight of high accuracy systems of the type and zero drift, low dynamic range. Method, described in this article is based on the fiducial markers recognition. The markers were located on investigated object, their positions were estimated on four images, captured by four digital cameras, connected to the PC. The Results, obtained by four cameras, were processed by developed algorithm, allowing to conduct pose estimation with an accuracy of 0.2 degrees in 3 degrees of freedom.
The possibility of direct registration of the optical spectrum derivatives using the acousto-optic spectroscopy methods
Authors: Boritko S V , Karandin A V , Boritko Y S
Published: October 2020

Using the example of the spectrometer based on acousto-optical (AO) cell with jump phase manipulation developed at the Scientific and Technological Center of Unique Instrumentation of the Russian Academy of Sciences, the possibility of creating a new class of instruments, i.e. differential AO spectrometers with arbitrary addressing working in real time, is shown. In the paper it is calculated how the error value determining the maximum position changes when the position of the combined peaks changes, as well as the dependence of this error on the peak width and height.
A two-frequency mode to control acoustic field distribution inside cylindrical lens
Authors: Bykhanov A N
Published: October 2020

Acousto-optical (AO) interaction is one of the most effective principles for electronic control of the optical radiation characteristics. Further development of this approach may be related to the use of fluids as a working media. In this paper, it is proposed to optimize spatial distribution of the refractive index in acoustic lens by applying two frequencies simultaneously. The simulation results are given. The optimal frequency combinations in terms of the central lobe intenity are found.
Study on Strength Properties of Concrete using Pumice Powder Pozzolan and Polypropylene Fibers
Authors: Abraham Ansu Lalu , Mohan Regi P
Published: October 2020

The construction industry is flourishing day by day, as a result, cement consumption also increases. Since cement production causes carbon footprint, partial replacement using waste materials from various industries is one of the solutions. Pumice powder, generated by the stone processing industry, is an inert by-product possessing excellent cementitious characteristics. Utilisation of pumice powder in concrete can reduce the cost of construction and at the same time address the waste disposal problem. The fiber dispersion into concrete is one of the techniques to further improve the ductile properties of concrete. This study is focused on the strength properties of pumice powder pozzolan concrete reinforced with polypropylene fibers. Mechanical strength characteristics were evaluated for normal and varying contents of pumice powder and polypropylene fiber added mix after 7 and 28 days of curing. The results indicate that the strength properties of the modified mix has improved considerably. The significance of this study is to promote the usage of by-product waste as a replacement for cement thereby reducing CO2 emissions and thus resulting in the development of environmentally friendly concrete.
Design of Short Columns Reinforced with GFRP Bars Subjected to Axial Loading
Authors: Niyazuddin  , Kinjawadekar Trupti A , Nagarajan Praveen , Shashikala A P
Published: October 2020

Due to the ongoing environmental changes, degradation of directly exposed material is seen very often. This results in issues related to aesthetics, function, and most importantly, the safety of the structures. Reinforced cement concrete (RCC) is the most commonly used material for construction where steel bars are used as reinforcement. Steel reinforcement in contact with the chemicals like chlorides and sulphates etc. which are very commonly present in urban and industrial areas and other aggressive environment, gets corroded, thus affecting the structural behaviour. Research studies propose replacing steel rebars with Glass Fibre Reinforced Polymer (GFRP) bars due to its non-corrosive properties. This paper presents the analysis and design of GFRP reinforced concrete columns. Present design methods mentioned in Indian Standard Code are not applicable to design GFRP reinforced RC columns directly. This study is an attempt to develop design provisions for GFRP reinforced concrete columns similar to those in practice for steel-reinforced columns. The spacing of ties influences the capacity of the column to carry load and failure type of compression member. So, this paper will also focus on the design of ties to provide proper confinement.
An Investigation on Pozzolanicity of Mechanically Activated Pond Ash
Authors: Vidyadhara V , Gowda T Shamanth , Ranganath R V
Published: October 2020

Pond ash (PA) is one of the major industrial solid wastes from thermal power plants. In the present study, PA of different storage durations, i.e. freshly ponded, two year ponded and Six-year ponded ash were collected from Bellary Thermal Plant (BTP). All three kinds of PA were mechanically activated by grinding in Industrial Hammer Mill. Unprocessed Pond Ash (UPA) and Ground Pond Ash (GPA) were characterised for Particle Size Distribution (PSD) by Laser-diffraction analyser. Mineralogical and Morphological characteristics were analysed through X-ray Diffraction and Electron Microscopic studies. Chemical composition of PA was analysed. The pozzolanicity of PA and other Supplementary Cementitious Materials (SCM) was determined and compared by conducting Lime reactivity test. XRD patterns and Chemical analysis clearly indicate the presence of relatively more amorphous phases in a fresh batch of PA compared to the one which is ponded for a longer duration. Lime reactivity strength (LRS) of UPA was far behind the LRS of commonly used SCM’s. Mechanical activation of PA improved the LRS from 0.57 MPa to 2.41 MPa. The results suggest the possibility of enhancing the reactivity of PA with early use and more efficient grinding process, thus add value to PA for its use in concrete.
Impact Resistance of GGBS-Dolomite Geopolymer Concrete
Authors: Saranya P , Nagarajan Praveen , Shashikala A P
Published: October 2020

Geopolymers are new alternative binders for cement in which polymerization gives strength to concrete. The present study highlights the development of geopolymer concrete from industrial by-products such as Ground Granulated Blast furnace Slag (GGBS) and dolomite. They are obtained from steel industries and rock crushing plants respectively. Standard mix design guidelines are not available for geopolymer concrete. The trial and error method was chosen for attaining a target compressive strength of 60 MPa. Impact strength plays an important role in structures like bridges, harbours, and barriers. The present paper investigates the impact resistance of GGBS dolomite geopolymer concrete using drop weight method. Procedures of ACI Committee 544 were used, and results were compared with that of cement concrete. Cylindrical specimens having 150 mm diameter and 50mm thickness were used. Maximum impact resistance was observed when GGBS and dolomite become 80:20, which is 42% more than GGBS geopolymer concrete without dolomite.
Recycling of Domestic Plastic Waste Bags as Fine Aggregate in Concrete
Authors: Bag Ramakrishna , Agarwal Aman , Praneeth Ranga
Published: October 2020

Plastic has been used in many ways in modern life both in industry product as well as in domestic use. The waste generated by using plastic poses an enormous threat to the environment due to its non-degradable nature for a very long time. There has been a lot of effort to minimise plastic waste generation and reuse it. However, the plastic waste generation has been increased considerably in the past decade. This paper presents a potential use of plastic waste as fine aggregate in concrete. Experimental investigations were carried out to determine the strength characteristics of concrete by replacing fine aggregate with 10, 15, 20, and 25% of processed plastic waste. Tests were conducted on concrete specimens under tensile, compressive, and flexural loading conditions to understand its behaviour. Although there was a notable reduction in strength characteristics of the concrete specimens, the optimum strength was obtained at 15% sand replacement. The concrete mix prepared using plastic waste can be used for mass concreting and low load-bearing structures.
Precast Bamboo Reinforced Furniture Elements using Self Compacting Concrete
Authors: Vengala Jagadish , Namratha K B , Anusha S
Published: October 2020

Public furniture in India are designed based on ergonomics standards derived from the international standards proving a significant hurdle in comfort for the users. We propose to tackle this by conducting ergonomic studies of true users. This study aims to check the viability of using an eco-friendly composite as street furniture, i.e., Park Bench. Additionally, owing to the increasing negative impact steel manufacturing has on the environment, the furniture is designed using a Bamboo-SCC composite. The objective of the study is to use bamboo as reinforcement in SCC to make furniture. The furniture is made using self-compacting concrete to ensure greater stability of the bamboo reinforcement and further to increase the durability of the benches. The final product is analysed based on deflection tests, cost-benefit analysis, and embodied energy savings. It was concluded that in areas where bamboo is readily available, this project can be implemented as a more energy-efficient and low-cost option.
A Comparative Study on FBD and DBD Methodology with Emphasis on Bridges with Seismic Irregularity
Authors: Abey E T , Somasundaran T P , Sajith A S
Published: October 2020

One of the major developments in seismic design over the past few decades is the increased emphasis for limit states design now generally termed as Performance Based Engineering. Performance Based Seismic Design (PBSD) uses Displacement Based Design (DBD) methodology where-in structures are designed for a target level of displacement rather than Force Based Design (FBD) methodology, where-in force or strength aspect is used. Indian codes still follow FBD methodology compared to other modern codes like CalTrans, which follow DBD methodology. Hence in the present study, a detailed review of the two most common design methodologies i.e. FBD and DBD will be discussed, along with its comparison on bridge models with and without ‘seismic regularity’. Bridges with irregular column height are studied to discuss the inherent discrepancy associated with FBD while dealing with ‘seismic irregularity’.
Seismic Fragility Analysis of Bridge Pier
Authors: Jain Ankit , Davis Robin , Nanda Kumar C G
Published: October 2020

Bridges are classified as lifeline structures as they need to be functional in an earthquake event. The performance-based analysis of the existing bridges is important for the stakeholders. Information on seismic performance in terms of fragility of existing bridges in the country can provide valuable information to the decision-makers. This study focuses on the development of seismic fragility curve, which is the probability of exceedance of a defined damage parameter of the bridge pier under a given ground motion intensity and development of damage index function of bridge piers. Existing bridge piers are considered and peak ground acceleration is taken as ground motion intensity measure and drift at the pier top level is considered as the damage parameter.
Highway Steel Composite Bridge Design using Limit State Design Method
Authors: Sabu Chinnu , Nagarajan Praveen , Davis Robin
Published: October 2020

Bridges are the pathways constructed over the obstacles without changing the alignment of the way beneath. While considering the design of steel composite bridges, Indian code is in the revision process; from Working Stress Method, it is updated to Limit State Design under IRC 24:2010. This paper illustrates a design example of a steel composite highway bridge with both longitudinal girders and cross girders under Limit State Design using IRC 24:2010 and IRC 22:2015. The concrete deck slab and steel girders together act as a composite structure which is connected using shear connectors. The effective span of the bridge is taken as 35m. There are four longitudinal girders having a spacing of 2750 mm c/c and cross girders are considered with spacing 5500mm c/c.
Optimal Design of Tuned Mass Damper for Base-Excited Structures
Authors: Banerjee Sarranya , Ghosh Aparna (Dey)
Published: October 2020

The tuned mass damper (TMD) is a well-established vibration control device that has been implemented in several structures worldwide. The performance of passive TMD is greatly dependent on its design parameters. A key issue for the design of the optimal TMD is the identification of the parameters of the structure to which the TMD is to be attached. Here, it is important also to consider the perturbations that may arise in the structural frequency due to different practical issues. The present work focusses on this and aims to obtain the optimum TMD parameters in a Genetic Algorithm (GA) framework. The results of the proposed optimal strategy, in terms of optimal tuning ratio and optimal damping ratio, for a given value of the mass ratio, are compared with some of the existing optimal solutions for linear TMD under base excitation. The effectiveness of all these optimally designed TMDs in reducing the structural response is further demonstrated when the structure-TMD system is subjected to recorded earthquake ground motions. It is seen that in the tuned condition, the control performance obtained by the different designs of the TMD are similar to each other, although having some minor differences in the values of the optimum parameters. Also, the effectiveness of the different TMD designs in the detuned condition is investigated, in which the present design technique is found to be the most effective.
Effect of Water-Cement Ratio on Mix Design and Mechanical Strength of Copper Slag Aggregate Concrete
Authors: Panda Swetapadma , Sarkar Pradip , Davis Robin
Published: October 2020

In concrete, the distinct influence on most or the entirety of the properties is the measure of water utilised in the matrix. In concrete mix design, the water-cement ratio is responsible for binding all constituents of concrete together. If the water-cement proportion is higher, it brings about wider spacing between the cement aggregates and thus, influences the compaction. Correspondingly, concrete’s durability and compressive strength are decreased due to increased dampness levels. Especially with added fine aggregates the water demand increases because of the increased surface area of concrete which prompts a higher water-cement ratio. Wider spaces are formed between the aggregate materials with the addition of extra water and when the moisture vaporises, voids are filled up with air. The subsequent insufficient compaction lessens the concrete’s strength. Sets of basic experimental investigations were conducted to examine the impact of various water-cement proportion on mix design and mechanical strength of concrete incorporated with fine aggregate in terms of copper slag. Natural sand replaced with copper slag with four different percentage and correlation coefficients between mechanical properties of copper slag concrete were also evaluated.
Non-linear Behaviour of Infilled RC Frame
Authors: Zade Nikhil P , Koparde Shivprasad A , Sarkar Pradip , Davis Robin
Published: October 2020

The reinforced concrete (RC) infilled frame is very common in exercise. In general, only infill weight is considered in the design of the RC infilled frame, and the strength of masonry is ignored. However, the prominence of masonry infill on the seismic behaviour is highlighted during past earthquakes. Nowadays, applications of different types of masonry such as fly ash, and lightweight masonry in infill, are increasing due to their superior properties over the traditional clay brick masonry. The exact behaviour of the infilled RC frame during an earthquake cannot be predicted if the strength of infilled is ignored. A nonlinear static method i.e. pushover analysis for the seismic evaluation, is commonly used due to its simplicity and high accuracy. A typical four storey three bay plane infilled RC frame is considered in the present study to investigate efficacy of several formulas available in the literature for the modelling of infill employing pushover analysis method. In addition to that sensitivity analysis also conducted which revealed that the parameters, masonry wall width and masonry shear strength are significant that control the base shear at yield level. Significant decrease in the lateral stiffness is observed for a higher percentage of openings in the infilled. However, up to 5% of openings in infilled can be ignored due to its marginal change in the lateral strength of infill.
A Study on Challenges in the Rehabilitation of Large Masonry and Concrete Dams
Authors: Jiji Panicker K , Nagarajan Praveen , Thampi Santosh G
Published: October 2020

Large dams retain enormous volume of water intended for various purposes. The design, construction, operation and maintenance of these special structures are of paramount importance considering its uses and safety. Safety of the dam is to be ensured throughout its’ life from structural, hydrological and operational perspectives as its failure would be catastrophic. Periodical safety inspections, review on safety, dam health monitoring as well as risk assessments are measures to ensure safety of these large structures. Ageing of dams is a concern in dam safety as there can be inadequacies or deficiencies with respect to structural, hydrological and operational requirements. Revision of relevant codes of practice/standards also may necessitate review and strengthening. As such, these structures are to be rehabilitated to the prevalent standards and maintained healthy to continuously derive the benefits envisaged during construction. Rehabilitation of dams aims to bring it back to a good condition and ensure that it does not pose a risk to the stakeholders downstream. The process involves various systematic procedures such as review of structural design, review of design flood and diagnosis using non-destructive tests to detect possible deterioration in its health, etc. As per recent statistics, more than half of the large dams in India are more than 25 years old. In this paper, a review of aspects such as challenges, considerations as well as various factors involved in the effective implementation of rehabilitation/strengthening is presented. Certain case studies of rehabilitation work undertaken under the on-going Dam Rehabilitation and Improvement Project in India are cited to bring forth the importance of such measures. As dams play crucial role in the prosperity of the nation, they are to be maintained for an endured life without jeopardizing the safety of the structure. In that perspective, rehabilitation of dams or its strengthening process is extremely important.
A Software Tool to Estimate the Time-dependent Deformation in RC Walls and Columns
Authors: Sahay Varun , Shariff M N , Menon Devdas
Published: October 2020

Tall reinforced concrete (RC) buildings are sensitive to time-dependent effects which arise due to creep and shrinkage. In this study, a software tool has been developed to estimate the time-dependent deformations in RC walls and columns. The program can invoke the ACI 209, EC 2, IS 1343 and fib MC 10 models to determine the creep and shrinkage in plain concrete. In order to include the effects of longitudinal reinforcement, two alternative methods have been explored: (i) effective modulus method and (ii) one-dimensional boundary value problem method. The effect of variable environment is included using the principle of superposition, which is valid within the linear creep domain. The program is written on the Python platform and can be used on any Windows machine. The program is validated using tests reported in the literature. The program is capable of accepting input of a linear elastic one-step-analysis from standard commercial software like ETABS and StaadPro. This program requires minimal input from the user, such as the grade of concrete, rate of loading and time at which the deformations are to be evaluated. The time-dependent deformations are evaluated for each column or wall and the super-elevation levels for each story are presented in a chart form, which serves as a design aid for the engineers and can be readily used by the site construction team.
Experimental Study on Microbial Concentration Optimization in Cement Mortar using M-Sand as Fine Aggregate
Authors: Benjamin Babitha , Sabbavarapu Anisha , Sudhakumar J , Suchithra T V
Published: October 2020

One of the major shortcomings of conventional concrete based constructions is its gradual strength deterioration over time due to its week tensile strength. Without any effective measures to remedy this problem the alternatives we have now are periodic monitoring, retrofitting, repair & rehabilitation, etc. The above-mentioned methods are all highly unsustainable due to manpower, money and materials being spend in a cycle to upkeep. If a protective coating of microbial cement mortar is given to the structures like bridges, underground tunnels, etc. were a lot of dampness is observed, structural deterioration can be prevented. The study is aimed at optimizing the concentration of bacteria in self-healing cement mortar which uses microbiologically induced calcium carbonate precipitate to induce crack healing ability. For this purpose, bacteria Bacillus Subtilis
MTCC441 (non-ureolytic) were added in concentrations 104, 106, 108 cells/ml to a mix using M-sand as fine aggregate. The bacteria were cultured in a nutrient broth and were added to cement mortar by water medium during mixing. The addition to cement mortar was done when the microorganisms were still alive and active. In this study, a series of experiments like compressive strength, water absorption, and pour healing was done to optimise the concentration. The results showed that 106 cells/ml was the optimum quantity of microorganisms required to enhance the physical properties of concrete.
Enhancement of the Seismic Performance of Open Ground Storeyed Building using X-bracings
Authors: John Shemin T , Sahu Deepak Kumar , Sujeesh S , Sarkar Pradip
Published: October 2020

High rise buildings are rapidly increasing in India, and the reason is the unavailability of land. The latest developments in the construction industry improved the utility of available space in productive ways. Perhaps the most recent pattern in the development field is Open Ground Story (OGS) encircled structures, where the ground story is kept open without infill dividers mostly because of points of interest on parking facilities. The ground storey of these buildings are considered as soft and weak, making it most vulnerable to earthquakes, and incorrect structural designing of these buildings will result in catastrophic failure. It is found that the addition of steel bracings significantly improves the seismic performance of OGS buildings in recent years. The motivation of the present study is to focus on the OGS framed buildings with and without steel bracings. In this work, a combination of conservative lateral load resisting systems such as X-bracings and multiplication factor is employed along with moment resisting frame to develop a hybrid system thus by improving the seismic performance of OGS structures.
Strengthening of Confined Masonry Structures for In-plane Loads: a Review
Authors: Gupta Akshay , Singhal Vaibhav
Published: October 2020

Confined masonry is a load-bearing masonry structure where walls are confined with nominally reinforced concrete elements at key locations. This building typology is popularly used in many countries as it generally performs better than the unreinforced masonry and non-ductile RC infill masonry under seismic loads. However, the confined masonry buildings have also experienced damage during past earthquakes. Poor seismic performance is generally seen due to construction errors, design flaws or material deficiencies in the building design and construction process. To overcome the structural deficiencies researchers have used different strengthening techniques for confined masonry walls such as application of ferrocement overlay, steel bands, and fiber-reinforced polymers. There are several inherent advantages and disadvantages of these strengthening techniques in terms of efficiency, bonding with the substrate material, durability, ease in construction and economy. This article will review and discuss the in-plane strengthening of confined masonry walls with conventional and fiber-reinforced materials and will highlight the gap areas and scope for future research.
Investigation on Rehabilitation of Circular RCC Columns with FRP Composites
Authors: Bindurani P , Ganesan N , Indira P V , Yadav V R
Published: October 2020

A detailed experimental investigation was done on the effect of rehabilitation using (i) carbon fibre reinforced polymer (CFRP) and (ii) glass fibre reinforced polymer (GFRP) on reinforced cement concrete (RCC) circular columns in order to compare the rehabilitation potential of these selected composites. The CFRP and GFRP laminates respectively consist of unidirectionally woven carbon fibre mat (230g/sqm) and bidirectionally woven glass fibre mat (220g/sqm), both impregnated in the same epoxy resin matrix. Even though there are many studies reported in the literature, comparative studies among these composites are limited. In order to have a level playing field, tension tests have been conducted on test coupons of these composites, and it was found that one layer CFRP was equivalent to 3 layers GFRP. In this study, pre-distressed RCC circular columns of 150mm diameter and 850mm length were rehabilitated with these equivalent laminates and tested under uniaxial compression. For rehabilitation purposes, the levels of pre-distress induced were at 70%, 80% and 90% of the ultimate capacity of the specimen. The compression behaviour of the rehabilitated columns was compared in terms of strength and serviceability. It was noted that both the composites improve the strength significantly, and CFRP performed much better than GFRP in terms of strength and serviceability.
Utilisation of Ultra-High Performance Fiber Reinforced Concrete(UHPFRC) for Retroffiting – a Review
Authors: Jose Josniya , Nagarajan Praveen , Remanan Mini
Published: October 2020

Retrofitting has become a proven method for improving the load carrying capacity of existing concrete structural elements subjected to high mechanical loading, ageing or aggressive environments. Ultra-High Performance Fiber Reinforced Concrete (UHPFRC)is a relatively new generation of cement-based retrofitting material with a very high compressive strength and low permeability attributed to its tightly packed microstructure, also displaying excellent bonding ability with normal structural concrete. It has the potential to eliminate various problems caused by other retrofitting methods like FRPs or externally bonded steel plates as a result of the mismatch of stiffness with parent concrete. This study presents an overview of UHPFRC focusing on its properties, design, applications and challenges. The performance of UHPFRC concrete mix is greatly influenced by the type and degree of packing of its constituents in the cementitious matrix, necessitating the need for optimisation. Strength properties are very much higher when compared to that of conventional concrete alongside with increased durability aspects. The retrofitting technique showed an enhancement in the load carrying capacity of deteriorated structures. Therefore, UHPFRC can be considered as a practical solution to improve the sustainability of buildings and other infrastructural components. However, as a retrofit, there are some concerns regarding the loss of ductility. This broadens the need for methods to improve its ductility. This paper presents the state-of-art review of existing literature that deals with the retrofitting/rehabilitation of structures using UHPFRC. Altogether, the paper aims to expand the awareness regarding UHPFRC which was otherwise hindered, owing to limited design codes.
A Review on Fractal Analysis and its Applications in Structural Engineering
Authors: Anwar Ayisha , Adarsh S
Published: October 2020

Fractals refer to rough or fragmented geometric shape in which each sub-section is a reduced-size copy of the whole. Its potential to describe the complex and irregular phenomena leads to wider applicability, and its enormous unexplored potential in the field of structural engineering is to be attended by the research community. This paper first presents a brief theoretical background of the most popular algorithms, such as the box-counting method, Multifractal Detrended Fluctuation Analysis (MFDFA), and Multifractal Detrended Cross-Correlation Analysis (MFDCCA). This paper further presents a comprehensive review of the potential of fractals and multifractals in four specific domains, such as crack identification, pore structure analysis and chloride resistance, and structural damage detection. The review of literature further reveals that 2 dimensional and multi-dimensional extension of fractal theory can be effectively coupled with image analysis for micro-level examination of pore structures, which opens the scope for abundant applications in research in the field of structural materials. The applications of MFDFA and cross-correlation analysis structural health monitoring are very recent research contributions in the field, and they are in the infant stage of applications. The review of research works performed in this study shows that the complete potential of fractals in the structural engineering field is not yet explored by the researchers.
Production and Utilisation of Artificial Coarse Aggregate in Concrete - a Review
Authors: George George K , Revathi P
Published: October 2020

This present work provides a study of several successful approaches in producing artificial aggregates using a pelletiser machine and the parameters affecting efficiency. These aggregates were contrived from substances of nature such as fly-ash, GGBS, Rice husk ash, volcanic ash, etc. Different sets of artificial aggregates are to be made with different molarity. The common methods of developing them include cold bonding, autoclaving, and sintering. The aggregate pellets (with lightweight and possessing less specific gravity and high impact value than gravel) were batch manufactured by a cold bonded technique using disc pelletiser (used to perform agglomeration). The prepared aggregates are characterised based on their crushing and impact strength rate and also moisture absorption. This paper explicitly reviews various effective and eco-friendly artificial aggregate and their potential usage in the construction industry.
Design of Flexural Members Reinforced with GFRP Bars
Authors: Sethi Abinash Kumar , Kinjawadekar Trupti A , Nagarajan Praveen , Shashikala A P
Published: October 2020

Reinforced concrete has emerged as a primary construction material since the nineteenth century. A passive combination of concrete and steel reinforcing bar (rebar), this composite material is widely used in various types of structures. However, corrosion of steel reinforcement has been identified as a significant problem affecting the structural integrity of such concrete structures. In this context, the use of GFRP bars is gaining prominence due to their non-corrosive nature. This paper presents behaviour of flexural members reinforced with GFRP bars. The strength reduction factors and guidelines available with different codes for flexural members are studied. The design of flexural members reinforced with GFRP bars has been done using Indian Standard code parameters. The flexural capacity of the beams is estimated from the strain compatibility and equilibrium of forces. The theoretical and experimental results are compared. It is seen that designing the beams as an over-reinforced section will increase the stiffness of the beams.
Effect of Adhesive Debonding on Static and Dynamic response of PZT Bonded Aluminium Beam
Authors: Aslam Mohammed , Nagarajan Praveen , Remanan Mini
Published: October 2020

Piezoelectric actuators and sensors have been extensively used in smart structures. A structure becomes smart when piezoelectric patches are either surface bonded or embedded into the host structure. Under the application of electric potential piezoelectric materials may expand/contract, which serves them as an actuator. Similarly, when it gets strained, an electric potential is induced, which serves them as sensors. Piezoelectric materials (PZT) are usually surface bonded to the structures using suitable bonding agents. This bonding agent plays a crucial role in transferring the forces from the piezoelectric layer to the host layer. This paper presents the effect of adhesive debonding on static as well as dynamic response of PZT bonded aluminium beam. The results show that debonding failure adversely affects the actuating capabilities of the PZT transducer. It is seen that the tip displacement decreases with increase in debonding size. The results also highlight that neglecting the adhesive layer in the finite element (FE) models overestimates the tip displacement as well as its natural frequencies.
Hysteresis Behaviour of Precast Shear Wall – Slab Connection under Reverse Cyclic Loading
Authors: Arthi S , Jaya K P
Published: October 2020

An experimental study focused on precast shear wall-slab joint failure is presented in this paper. For the precast specimen, the shear wall and slab are precast members and were connected with cast-in situ concrete using dowel bars. The specimen was tested under reverse cyclic loading and the structural behaviour of the connection was evaluated. The parameters considered are cracking pattern, hysteresis behaviour, energy dissipation and ductility. This study also aimed to develop 3-D finite element (FE) model of precast shear wall – slab dowel connection using ABAQUS software in order to investigate the joint failure of the specimen such as damage and hysteresis behaviour. The non-linear behaviour of concrete was defined using concrete damaged plasticity (CDP) model and the interactions between the precast members were modelled using cohesive element. FE model was then validated against the experimental results of precast dowel connection which are vulnerable to wall-slab joint shear failure. The failure pattern of the tested specimen showed the “Strong joint-Weak member” concept. The comparison between experimental and numerical results showed that the FE model developed was capable of simulating the seismic performance and the joint failure of precast shear wall-slab connection using dowel bars.
Deep Learning-based Metamodeling Technique for Nonlinear Seismic Response Quantification
Authors: Kundu Anirban , Chakraborty Subrata
Published: October 2020

Classical physics-based numerical techniques such as finite element method (FEM) usually takes a huge computational resource and time for simulation-based uncertainties in structural analysis. Especially, it is expensive when nonlinear time history analysis is involved. The metamodeling technique becomes an alternative with an ability to predict the time history response of both elastic and inelastic structural system in a data-driven fashion. Various machine learning and deep learning-based techniques have been attempted to have their limitations in handling huge and sequential data while it comes to predict the whole response time history given stochastic ground motion acceleration. In this regard, Long Short Term Memory (LSTM) approach is found to be useful. The present study used LSTM deep learning network based metamodeling approach for nonlinear seismic response history approximation. The novelty of the approach lies in its capability of capturing record to record variability even for an inelastic structure. This metamodel can work with the desired level of accuracy with very limited data. The proposed approach has shown satisfactory results to approximate seismic response of a nonlinear single degree of freedom system.
Failure Mode Recognition of Columns Using Artificial Neural Network
Authors: Edward Chippy , Balu A S
Published: October 2020

Columns are one of the most vital segments in bridgessince its post-seismic behaviour is of much importance. The retrofitting methods and rehabilitation strategies of bridges mainly rely on the identification of the failure mode of columns. It has been witnessed in various studies on columns that the mode of failure highly depends on section and material properties and there is no specific boundary between the modes, which makes their identification more sophisticated. This paper uses an artificial neural network to predict the modes of failure by analysing the effects of such soft computing methods. In this study, machine- learning models were generated from the experimental data of 253 columns of rectangular cross-section and its accuracy of failure mode prediction was evaluated by considering failure modes mainly flexure, flexure-shear, and shear. The optimal input parameters have also been evaluated for the machine-learning algorithm that enhances the efficiency of failure mode prediction.
A Review on Strut and Tie Methods
Authors: Bhanu Kannan C , Ganesan N , Indira P V
Published: October 2020

Strut and tie method (STM) provides simplified solutions to complicated design problems. It was an evolutionary discovery which lead to an improved understanding of shear and flexural deformations of the structures. STM is applicable to the regions of the structure where beam theory is not valid. Numerous studies were conducted in this field, and various modifications are being attached to the conventional STM. Indeterminate models replaced determinate models, and nonlinear analysis replaced linear elastic analysis. New ideas like automatic generation of models based on optimisation techniques, simplified inelastic analysis using secant stiffness method and 3-dimensional analysis were also introduced. This paper summarises some of these studies and discusses their merits and limitations. Some suggestions to simplify these complicated methods are also included.