International Journal of Structural Engineering (18 papers in press)
Prediction of temperature distribution and fire resistance of RC slab using Artificial Neural Networks
by Nagat Zalhaf, Mariam Ghazy, Metwally Abd Elaty
Abstract: This paper present the use of artificial neural networks as alternative approach for predicting the temperature distribution of RC slab and its fire resistance according thermal criteria (the temperature of reinforcement criteria and the temperature of unexposed surface criteria). The predicted fire resistance compared with target fire resistance in codes of EN 1992-1-2 and ACI 216.1 Two set of data are used in training and testing two different ANNs. Data set 1 which consists of temperature profile for siliceous aggregate concrete slab presented in EN 1992-1-2. Data set 2 represents the temperature profile for carbonate concrete slab presented in ACI 216.1. Two ANNs models have been constructed. The first ANN is used to predict the temperature distribution in RC section. Second ANNs have been used to predict the fire resistance of RC slab. These models are used to study the effect of different parameters include aggregate type, slab thickness, concrete cover and reinforcement type on the fire resistance of RC slab. The results showed that ANNs can predict the temperature in RC slab section and its fire resistance with a good accuracy. Also, the ANNs models are succeed in predicting the effect of different parameters in the resistance of RC slab.
Keywords: prediction; temperature distribution; fire resistance; RC slab; artificial neural network (ANN).
Evaluation of Linear Visco-elastic Model of Quintuple Friction Pendulum Isolator
by Ankit Sodha, Devesh Soni, Sandip Vasanwala
Abstract: The Quintuple Friction Pendulum (QTFP) isolator is an extended technology of Triple Friction Pendulum (TFP) isolator having nine stage sliding regimes operation with five effective pendula. Although non-linear hysteretic model of the QTFP system allow a detailed appraisal of response by means of nonlinear time-history analyses, such analyses are dilatory and not suitable for the early stages of design where appropriate configurations are required for the desirable performance. However, it would be favorable to have a linear visco-elastic model to determine peak dynamic response parameters at the preliminary design to achieve desirable performance. The linear model is characterized by the equivalent effective stiffness and effective damping of the isolation system. A comparative study of linear and non-linear model of the QTFP for response quantities like isolator displacement, base shear and top floor absolute acceleration are presented under earthquakes of three different hazard levels with various probability of exceedance. It is observed that the linear visco-elastic model gives consistently good and conservative estimate of peak isolator displacement and base shear whereas, it under-predicates the floor acceleration as compared to non-linear model. Further, the effect of superstructure flexibility for both models is studied and linear model is found suitable for flexible superstructures too.
Keywords: Seismic Isolation; Quintuple Friction Pendulum System; Multi Hazard Level Earthquake; Linear Visco-elastic model.
ELEMENT DAMAGE ASSESSMENT IN SEMI RIGID CONNECTED STRUCTURES USING MODAL DOMAIN DATA
by Bharadwaj Nanda, Damodar Maity, Dipak Kumar Maiti
Abstract: Current vibration based damage assessment techniques assumes that the joints in a structure behave either perfectly rigid or perfectly flexible. However, joints in the bolted structures are semi-rigid, which means the elements may show rotations to a certain degree on the basis of a fixity factor. In this regard, the present work proposes an alternate solution to conventional inverse damage identification problems by providing due weightage to the joint rigidity. The beam-column joints for this study are made semi-rigid by reducing their end fixity factor. An inverse problem is formulated here the purpose of using changes to natural frequencies and mode shape vectors caused due to damages, which is then solved by a unified particle swarm optimization algorithm. The efficacy of this procedure is demonstrated by conducting a few numerical and experimental studies. The outcomes suggest that the developed procedure is able to locate and quantify damages in a semi-rigidly connected structure with significant accuracy.
Keywords: Element damage identification; Semi-rigid connection; Modal data; Inverse problem; Stiffness reduction factor; Unified particle swarm optimization.
Performance improvement of rigid connection by reduced web section with Cellular beam and column subjected to cyclic loading
by Kitjapat Phuvoravan
Abstract: The behavior under cyclic loading of a Cellular beam and Cellular column on the beam-to-column rigid connection was studied. The main focus was at the connection when openings were implemented to the beam and column members. The study aims to determine the increase of the yield and ultimate strength of the whole rigid connection, the ductility of connection and the energy dissipation in each loading cycle. Finite element analysis with both nonlinear material and geometry was conducted. The case studies included the original commercial wide-flange member, a Cellular member, a member with the same size as the Cellular but with no web opening and a member with the same size as the Cellular but with only one opening at the beam near the connection. The results indicated that the implementation of a Cellular member could increase the yield strength of the overall rigid connection by 28.81%, the ultimate load by 30.93% and the stiffness by 36.21% compared to the original. Whereas failure usually occurs at the connection due to brittle behavior resulting from welding failures, the results showed that such failure can be effectively shifted to occur at the opening. The energy dissipation behavior of the overall rigid connection is improved in the early loading cycles, with small to medium rotation up to 0.14 radian.
Keywords: Cellular beam; Cellular column; Web-opening; Cyclic load; Rigid connection; Energy dissipation; Reduced web section.
Prediction of Ultimate Load Carrying Capacity of Castellated Beams by Experimental and Analytical Investigation
by Amol J. Mehetre, Rajashekhar S. Talikoti
Abstract: Abstract: The aim of this research paper is to offer a new angle of web opening for hexagonal castellated beams to avoid failure due to shear stress concentration at the corner of the web opening and to investigate the ultimate load carrying capacity and deflection of hexagonal and rectangular castellated beams. This research is focused on hexagonal and rectangle openings of a castellated beam. This research includes testing of 18 castellated steel beams out of 21 numbers of steel beams and 3 solid beams to investigate ultimate load carrying capacity and deflection. The variables were considered are the angle of opening for hexagonal shape with 30, 45 and 60, and the equivalent length of opening for a rectangular shape. All the castellated beams were analysed by using ANSYS software and the results were compared with experimental outcomes. The experimental and ANSYS results for ultimate load carrying capacity and deflection shows good agreement. Experimental results showed that the castellated beam with 30 hexagonal web opening having 28.63% more load carrying capacity and 83.52% less deflection compared to the solid beam.
Keywords: ultimate load carrying capacity; angle of opening; length of opening; hexagonal and rectangular web opening; bending stress; shear stress; castellated beams; finite element analysis; ANSYS; deflection.
Effect of Masonry Infill Wall with Opening on Reinforced Concrete Frame due to Seismic Loading: Parametric Study
by Abu Sayed Mohammad Akid, Muhammad Harunur Rashid, Md. Habibur Rahman Sobuz
Abstract: This study aims to investigate the effect of masonry infill wall with opening on reinforced concrete frame due to seismic loading under the influence of story number and panel aspect ratio. For this purpose, a total of thirty-six building frames including bare frame and infill frame with door and window opening were analyzed by Equivalent Static Analysis (ESA) and Response Spectrum Analysis (RSA) using STAAD.Pro software. The seismic load was applied as lateral loading and then sway, story-wise deflection, inter-story drift, bending moment and shear of those frames were evaluated and compared. Results of the parametric study indicated that ESA exhibited higher results compared to RSA for a conventional design of building frames as the bare frame. The bending moment in infill frames with opening concentrated at the top of the ground floor level for RSA whereas it was at the bottom of the ground floor for bare frames. The maximum moment and shear in the infill frames with opening decreased 12-50% and 2-47% respectively compared to the bare frame due to the interaction of infill panels with the frame elements.
Keywords: masonry infill wall; reinforced concrete frame; infill frame with opening; seismic loading; bare frame.
A study on strain sensing property for Carbon fibre based RC beams without stirrups
by Arvind Kumar Cholker, Manzoor Ahmed Tantary
Abstract: This paper analyses strain sensing property and structural behavior of carbon fibre based concrete (CFBC) beams under four point loading. Three RC beams having varying reinforcement ratios and constant dimensions have been casted with carbon fibre based concrete at top and bottom surface in mid span for a length of 350 mm and depth of 55.5 mm. Carbon fibre based concrete was used for evaluating strain sensing property of RC beam under four point testing and to know its effect on structural properties of RC (reinforced concrete) beam. The obtained results of fractional change in electrical resistance at compression and tension side were quite similar to that of strain in the beams at compression and tension surface. Along with strain sensing test structural properties of the tested beams are reported in this paper. As there was no transverse reinforcement provided, all the beams failed due to shear failure.
Keywords: Carbon fibers; Electrical properties; Health monitoring; Shear; Self compacting concrete.
Estimation of Dynamic Design Parameters for Buildings with Multiple Sliding Non-Structural Elements Using Machine Learning
by S.P. Challagulla, C. Parimi, S. Pradeep, Ehsan Noroozinejad Farsangi
Abstract: The seismic behaviour of a primary structure (PS) with multiple sliding non-structural elements (NSEs)/secondary bodies (SBs) is investigated in this paper. Equations governing the motion of PS with SBs have been developed considering the Coulomb's friction model. Spectrum compatible ground motions associated with the two Indian seismic hazard levels were considered. A parametric study was performed to analyse the variation in the displacement of the structure by varying the structural period (T_p), the mass ratio (?_i), and coefficients of friction (?_si,?_ki). The results of the parametric study demonstrate that the sliding blocks behave as rigidly attached bodies to the structure for higher structural periods and frictional constants. A novel method is proposed to calculate the modified structural period (T_new) with multiple sliding rigid blocks. Finally, design equations for T_new are proposed by utilizing the machine learning technique like Artificial Neural Network (ANN).
Keywords: primary structure; secondary bodies; coulomb friction; sliding element; seismic hazard levels; non-structural element; ANN.
Forced Vibration Analysis of Laminated Composite Stiffened Plates
by Leena Sinha, Trushna Jena, Amar Nath Nayak
Abstract: The extensive parametric study on the forced vibration characteristics of laminated composite stiffened plates using finite element method (FEM) is investigated in this paper. A nine noded isoparametric plate element with five degrees of freedom and a three noded isoparametric beam element with four degrees of freedom as stiffener element are appropriately combined together to obtain stiffened plate element. Newmarks method is applied to obtain the dynamic response of stiffened plates and is investigated for three different types of transient loads: Uniformly distributed step load of infinite duration, uniformly distributed step load of finite duration (1s) and uniformly distributed half sine load of finite duration (1s). The dynamic response analysis of laminated stiffened plate is conducted with respect to boundary conditions of the plate, number, type and orientation of stiffeners, stiffener depth to plate thickness ratio and types of dynamic loading. Significant effects of the above parameters are observed on the dynamic responses of the laminated stiffened plates. Reduction of displacement response of the laminated composite plate is noticed to a large extent with introduction of stiffeners.
Keywords: Finite element method; forced vibration characteristics; isoparametric element; laminates; stiffened plates.
Wind induced Interference effects on two, three and four building configuration
by Shruti Konka, Sabareesh Geetha Rajasekaran, P.N. Rao, Kalluri Ram Chandra Murthy
Abstract: Wind loading codes provide the guidelines to design isolated building structures resistant to wind. But presence of a structure in the vicinity can significantly alter the wind environment. Such phenomenon known as interference effects. Provisions for interference effects are inadequate in codes and standards. Several experimental studies were made on interference effects of group of buildings. As the number of buildings in the group increases, there exists multiple configurations. This in turn adds to the complexity and increased number of experimental cases. Limited studies exists which model interference effects of group of buildings using computational fluid dynamics (CFD) techniques. The present paper investigates on interference effects of two, three and four buildings arranged in different configuration exposed to different wind incident angles using CFD. Wind load enhancement or shielding is observed on different faces of building for the same interfering distance and height ratio depending on the configuration of building.
Keywords: Interference effects; wind incident angle; group of buildings; Turbulence,CFD; LES.
EXPERIMENTAL INVESTIGATION ON BOLTED FLANGED STEEL PIPE JOINT SUBJECTED TO FLEXURE
by Muhammad Monowar Hossain, Zasiah Tafheem, Khan Mahmud Amanat
Abstract: This paper presents an experimental study on the behavior of bolted flanged structural steel pipe joint subjected to bending. The sample was prepared by welding a flange to an end of a pipe segment and then joining the two segments of pipe by placing the flanges face to face and fastening using structural bolts through holes in the flanges. The whole assembly was then subjected to flexure by placing on a simple support arrangement and applying two-point loading. Total sixteen flanged pipe joint samples were tested having different pipe diameter, flange thickness, bolt diameter etc. The deformation characteristics of the joint demonstrated two different kinds of behavior: thin flange behavior and thick flange behavior. Thin flange behavior is characterized by local flexural deformation of the flange accompanied by prying action and some bending of the bolts while thick flange behavior is characterized by contact separation between flanges accompanied by tensile elongation of the bolts.
Keywords: Bolted flanged pipe joint; two-point loading; bolt shank; bolt tension.
Use of Angle Steel as Internal Reinforcement in Low Strength Concrete: an Experimental Study
by H.M.A. Mahzuz, Sourav Ray Ray, Ajoy Bala, Bijoy Chondo Jony
Abstract: Use of Angle Steel as Reinforcement in concrete is a prominent field of research nowadays.This paper presents an experimental study where angle steel is used as reinforcement in concrete members like column, beam, and frame. The effects were compared with the members prepared with the conventional round bar as reinforcement. It is found that structural RCC concrete members having angle steel performed better than the structural concrete members having conventional reinforcement.The study revealed thatthe load-carrying capacity of the column, beam, and frame reinforced with angle steel were 5.4%, 28.16%, and 42.29% higher than those of the column, beam, and frame respectively, reinforced with conventional steel; even though the yield strength of angle steel was less than the conventional rebar and also the steel usage was found 13.73% less for angle steel.
Keywords: Angle steel; cross-section; flexural strength; load carrying capacity; reinforcement; yield strength.
Simple mathematical model for piezoelectric coupled FGM plate subjected to dynamic studies
by Swapnil Patare, Kamal Bajoria
Abstract: Smart application of piezoelectric material is now well established through numerous studies. Piezoelectric material is used for sensing and monitoring purposes by coupling to main structure with piezo effect of generating current upon application of stress. FGM posses smooth property transition between two different material unlike laminated composite. Coupling of piezoelectric layers to FGM plate increases complexities from analysis point especially with analytical solution. Objective of present study is to develop simple mathematical model for free vibration analysis of FGM plate which can be further employed for smart application of piezoelectric material. Plate theory used here is based on four variable approach with two models with and without considering effect of thickness stretching. To consider combination of simply supported and clamped boundary conditions through analytical solution beam functions are used.
Keywords: functionally graded; smart piezoelectric material; free vibration; analytical solution.
Bond behaviour in rubberised concrete filled circular steel tubes
by Abdulrahman Khaleel Midhin, Abu Bakar Nabilah, Noor Azline Mohd. Nasir, Nor Azizi Safiee
Abstract: Rubberised concrete filled steel tube (CFST) is a potential method to utilise the crumb rubber as partial replacement of aggregate, however previous researches show weaker interfacial bond between the rubber and concrete. The aim of this research is to investigate the bond behaviour between the steel tube and the concrete in CFST. Push-out and mechanical tests were conducted on circular specimens, and the variables were: 1) different thicknesses of steel tube; 2) concrete types (normal, rubberised concrete and presence of metakaolin as pozzolan). The results indicated that the use of rubber gives adverse effect on the compressive and splitting tensile strengths, and the modulus of elasticity. However, the use of metakaolin as cement replacement improves its mechanical properties. Based on push-out test, the rubberised concrete shows lower bond strength, and the bond strength increases with increasing section thickness. The presence of metakaolin yielded higher bond strength compared with other mixes.
Keywords: rubberised concrete; concrete filled steel tube; bond-slip relation.
Seismic response of large diameter buried concrete pipelines subjected to high frequency earthquake excitations
by Roghayeh Abbasiverki, Anders Ansell
Abstract: Buried pipelines are tubular structures that cross large areas with different geological conditions. During an earthquake, imposed loads from soil deformations on pipelines may cause drastic damages. In this study two dimensional finite element models of pipelines and surrounding soils are used for simulation of seismic waves that propagate from the bedrock through the soil. The models describe both longitudinal and transverse cross-sections of pipelines and the soil-pipe interaction is described as a nonlinear behaviour. The effects of uniform ground with different burial depth and soil layer thickness, soil stiffness and non-uniform ground on the seismic response of reinforced concrete pipelines is studied. Two earthquakes, with high and low frequency contents, are employed for the dynamic analysis. The results show a significant effect on the response due to non-uniform ground caused by inclined bedrock, especially for high frequency earthquake excitations.
Keywords: buried pipelines; high frequency; finite element; seismic analysis; non-uniform ground; soil stiffness.
Modelling and calibration of infill frame-buildings, using ambient vibration tests and genetic algorithms
by Edgar David Mora, Jhon Jairo Aguirre, Jorge Luis Bone, Kléver Gastón Parra, Raúl Fernando Baquero
Abstract: The presence of infill walls modifies the global structural response of frame buildings subjected to seismic loads. In evaluation studies, the stiffness of the structural elements and the mass of the building do not have great scattering; consequently, the variable to be analysed is the stiffness of the masonry. This investigation presents a process to determine a more realistic calibration of an existing building model using structural software and genetic algorithm programs made in Python 3 where the properties of the masonry were iterated to obtain modal periods similar to those obtained from ambient vibration tests. This programming can be freely downloaded and can be used in any optimisation case. The results highlighted the influence that non-structural masonry has over the overall behaviour of a building. It is also demonstrated that the use of a simplified macro model, with one spring that depicts the nonlinear performance of masonry, is an excellent option to address the limitations of commonly used software, as well as reducing processing time.
Keywords: infill frame; ambient vibration; genetic algorithm.
Prediction of spectral acceleration of a light structure with a flexible secondary system using artificial neural networks
by S.P. Challagulla, C. Parimi, Jagadeesh Anmala
Abstract: The effect of a flexible secondary system (FSS) on the design spectra is studied in this paper. An FSS affects the primary structure (PS) during ground excitation differently than a secondary system that is rigidly attached to it. A modal superposition analysis is performed on a 2DOF system (PS + FSS). The influence of various parameters such as mass ratio and length of FSS on the design spectra is addressed. A methodology to estimate the spectral acceleration of the PS with FSS is developed. A design expression is proposed using statistical nonlinear regression and artificial neural network (ANN) to estimate the spectral acceleration of PS with FSS as a function of the structural period, length of FSS, and mass ratio. ANN modelling is proved to be more efficient than nonlinear regression model. An example calculation is shown for the estimation of spectral acceleration of the PS using ANN and nonlinear regression models.
Keywords: primary structure; flexible secondary system; FSS; design spectra; seismic zones; artificial neural network; ANN; nonlinear regression; NLR.
Seismic performance of reinforced concrete frame strengthened with an imperfect steel plate shear wall
by Mustafa Batikha, Yara Mouna
Abstract: In this research, the effects of imperfections in a steel plate shear wall (SPSW) used to strengthen a reinforced concrete (RC) frame were numerically examined using nonlinear finite element analysis. Three types of structures were analysed in this study: SPSW only, a one-story RC frame with an SPSW infill, and a multi-story RC frame with an SPSW. It was determined that the initial imperfections of a thin SPSW cause a dramatic reduction in the yield and ultimate capacity of the SPSW when analysed individually; however, the presence of RC boundary frame members addresses an important role in eliminating this reduction. In contrast, it was found that the SPSW prevents the shear cracking in the RC frame joints. Based on this point, a higher RC frame capacity together with high initial stiffness and ductility are registered when an SPSW is applied, and equations for estimating the system capacity were derived through this study.
Keywords: concrete frame; steel plate shear wall; SPSW; strengthening; finite element analysis; FEA; pushover lateral loading.