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Headed bars (HB) with different head shapes (Square, Circular, and Rectangular) and bar diameters (db: 16, 20, and 25 mm) embedded in steel fiber reinforced concrete have been subjected to pull-out test. The influence of head shapes, concrete compressive strength (M20 and M40), db, and steel fibers (0, 0.5, 1, and 1.5%) on the anchorage capacity of HB have been evaluated. Numerical model for improving the anchorage capacity of HB has also been proposed. Results have revealed that the anchorage capacity of HB increases with the increase in concrete compressive strength, db, and steel fibers, which have been validated by nonlinear regression analysis using dummy variables. Two failure modes namely, steel and concrete-blowout have been observed and the prevailing mode of failure is steel failure. Based on load–deflection curves and derived descriptive equations, it is observed that the circular HB has displayed the highest peak load.

Fiber-reinforced cementitious composites have been increasingly used during recent years on beam-column joints and the introduction of headed bars is a practical solution to eliminate the congestion problem caused by hooked bars in beam-column joints. The present study emphasizes the evaluation of the performance of steel fiber reinforced concrete (SFRC) external beam-column joints (BCJ) using headed bars as an anchorage mechanism and the comparison has been made with the conventional bars which have been detailed in accordance with ACI 318-19 and ACI 352R-02. The repository of previous BCJ work has been further expanded by researching the effect of structural parameters i.e. compressive strength (C20 and C40) and steel fibers (1 and 1.5%) on the hysteresis curve, ductility, stiffness, energy dissipation, and cracking on all specimens. The experimental results have revealed that the headed bars can be significantly replaced by the conventional bars for the areas vulnerable to earthquakes due to their higher load carrying capacity with better ductility and stiffness response and reducing congestion in BCJ.

Skew slab is the most common structural element that finds numerous applications in practice, especially when there is any space constraint that prevents the selection of either square or rectangular slab. Due to its geometry, this type of slab behaves differently in comparison to the rectangular slabs and it is a very time-consuming process to predict the moment field in such type of slabs. It becomes still more complicated when some beam system is used to meet the prescribed serviceability criterion. A set of mathematical expressions is presented in the paper that could be of help to predict the moment field being induced in skew slabs under external loads. The outcome of the proposed expressions is validated experimentally as well as numerically; a good agreement is observed in the results. An illustrative example is also presented in the paper to demonstrate the efficiency of the proposed expressions.

The skew slabs possess a broad range of applications in bridges as well as in buildings because of severe space constraints in the congested urban localities and in locations, when there ar...

The main objective of the study is to investigate the flexural behaviour of concrete sandwich panels strengthened with geosynthetics. Two types of geosynthetic material are being used viz. plastic geogrid and polyester geogrid. An attempt has also been made to enhance the strength by using two different mixes. The panels are tested under a monotonically increasing load using a hydraulic jack. The load–deflection curves of the panels were examined to evaluate the effect of geosynthetics on the strength, stiffness, and deformability of panels. The result shows that plastic geogrid reinforced sandwich panels enhanced the flexural strength and ductility of panels compared with control specimens. Polyester geo-grid as reinforcement is also found to be relatively better in restoring the deformability and energy absorption of panels. The results show a gain of about 28% in plastic geogrid (SPGG); 36.8% in the case of polyester geogrid (SGi200), in comparison with the control specimen. The moment–curvature curves were also examined.

The aim of the studyis to develop Pavement Maintenance Management System (PMMS) for four roadsections of urban road network (Patiala, Punjab, India) using HighwayDevelopment and Management (HDM-4) model. The HDM-4 provides a deterministicapproach in data input and process data of existing road condition, trafficvolume and pavement composition to predict road deterioration as per the urbanroad conditions in terms of International Roughness Index (IRI) value. Thisstudy presents the use of HDM-4 model for the computation of optimumMaintenance and Rehabilitation (M&R) strategy for each road section andcomparative study of scheduled and condition responsive M&R strategies. Theresults of present study will be useful for gaining better support for decision-makersfor adequate and timely fund allocations for preservation of the urban roadnetwork.

The plastic behavior of exterior beam-column joint with different fiber reinforced concrete (FRC) is explored experimentally under cyclic loading. Steel fiber and polypropylene fibers are used in fiber reinforced concrete and engineered cementitious composites respectively. A total of four specimens were prepared, among the four two specimens are conventional and remaining two are with different FRC. The hysteresis loop, stiffness degradation, energy dissipation and damage index are the considered parameters to quantify the plastic response of employed technique. The quantification of results shows enhanced load carrying capacity and energy dissipation capacity with lesser rate of stiffness degradation. The post failure analysis authenticates that the use of fiber improves the damage tolerance behavior and ductility enhancement without sudden loss in strength.

This paper presents a numerical study of moisture propagation in fibre reinforced polymer (FRP) materials with spatial tortuosity. An algorithm for creation of microstructures with clustered fibre architecture is presented. Several controls for different characteristics of the clusters are described. Different statistical descriptors of geometry are used to quantify the clustering. A Fickian diffusion process has been modelled. The effect of clustering on moisture diffusion through the FRP is reported. It is observed that microstructures greatly affect the diffusion behaviour of the FRP. Correlation between moisture diffusion and the statistical descriptors has been examined. The statistical measures that depict the global characteristics of the microstructure are found to have a better correlation with time to saturate the representative volume element. The results should help in prediction of macroscopic response and durability of FRPs.

The objective of the present study is to develop models to predict the deterioration of pavement distress of the urban road network. Genetic programming (GP) has been used to develop five models for the prediction of pavement distress: Model 1 for the cracking progression, Model 2 for the ravelling progression, Model 3 for the pothole progression, Model 4 for the rutting progression, and Model 5 for the roughness progression. The data have been collected from the roads of Patiala City, Punjab, India; during the years 2012–2015, the network of 16 roads have been selected for the data collection purposes. The data have been divided into two sets, that is, training dataset (data collected during the years 2012 and 2013) and validation dataset (data collected during the years 2014 and 2015). The two fitness functions have been used for the evaluation of the models, that is, coefficient of determination (R2) and root mean square error (RMSE), and it is inferred that GP models predict with high accuracy for pavement distress and help the decision makers for adequate and timely fund allocations for preservation of the urban road network.

Diffusion of moisture through fibre reinforced polymers (FRP) is one of the main environmental causes of their deterioration and loss of service life. Moisture diffusion and the resulting stresses in a fibre–matrix system vary considerably with the topology of the fibres inside the polymer matrix. This paper reports a numerical study on stress build up in FRP due to moisture diffusion. The Fickian diffusion model is implemented. Stresses due to the transient moisture distribution have been estimated using a finite element model. Some fundamental topologies have been studied. Most important topological parameters have been identified. Utilising the results of fibre neighbourhood, interpretation of large microstructures has been discussed. Considerable interactions among neighbouring fibres can be observed in the stress build up. The results should help in designing moisture impeding microstructures for FRP and prolong their life.

Influence of microarchitectural fiber matrix arrangement in representative volume element is studied to assess the effect of mass diffusion in the fiber-reinforced polymer composites. A novel approach has been proposed to illustrate the quantitative definition of the representative volume element heterogeneity using topological descriptor of clustering. Average fiber center distance from the fixed representative volume element center is described to compute the clustering in different representative volume elements, followed by finite element method simulation to model and visualize two-dimensional microstructures of fiber-reinforced matrix composites with moisture boundary conditions. The suggested topology descriptor shows good correlation with diffusion response in relation to saturation time, whereas a fair degree of correlation was observed for mass accumulation and mass flux characteristics. The results indicate that microstructural heterogeneity has a strong influence on typical moisture diffusion characteristics and hence, an overall diffusion-induced damage. The observations should serve as a clue to design the fiber-reinforced polymer composites with the moisture barrier properties.

Fiber distribution in a polymer matrix composite plays a key role in moisture transport which in turn affects its long term behavior. In this paper, effect of filament arrangement on moisture diffusion is studied. The emphasis is on the effect of neighborhood filaments on a single filament placed in a polymer matrix. Fickian diffusion has been simulated using finite element method. Several microstructures have been created using variable angular and spatial orientations of the filaments. Their saturation times have been recorded and analyzed. Microstructures for most favorable saturation time have been identified. The results show that the diffusivity of composites can be controlled through careful spatial design of filaments. The observations should serve as a clue for designing optimum filament geometry for impeding moisture ingress and improving durability of composites.

Many building codes use the empirical equation to determine fundamental period of vibration where in effect of length, width and the stiffness of the building is not explicitly accounted for. In the present study, ANN models are developed in three categories, varying the number of input parameters in each category. Input parameters are chosen to represent mass, stiffness and geometry of the buildings indirectly. Total numbers of 206 buildings are analyzed out of which, data set of 142 buildings is used to develop these models. It is demonstrated through developed ANN models that geometry of the building and the sizes of the columns are significant parameters in the dynamic analysis of building frames. The testing dataset of these three models is used to obtain the empirical relationship between the height of the building and fundamental period of vibration and compared with the similar equations proposed by other researchers. Experiments are conducted on Mild Steel frames using uniaxial shake table. It is seen that the values obtained through the ANN models are close to the experimental values. The validity of ANN technique is verified by experimental values.

Many building codes use the empirical equation to determine fundamental period of vibration where in effect of length, width and the stiffness of the building is not explicitly accounted for. Also the equation, estimates the fundamental period of vibration with large safety margin beyond certain height of the building. An attempt is made to arrive at the simple empirical equations for fundamental period of vibration with adequate safety margin, using soft computing technique of Genetic Programming (GP). In the present study, GP models are developed in four categories, varying the number of input parameters in each category. Input parameters are chosen to represent mass, stiffness and geometry of the buildings directly or indirectly. Total numbers of 206 buildings are analyzed out of which, data set of 142 buildings is used to develop these models. It is observed that GP models developed under B and C category yield the same equation for fundamental period of vibration along X direction as well as along Y direction whereas the equation of fundamental period of vibration along X direction and along Y direction is of the same form for category D. The equations obtained as an output of GP models clearly indicate the influence of mass, geometry and stiffness of the building over fundamental period of vibration. These equations are then compared with the equation recommended by other researcher.

A large number of civil structures were designed according to old seismic code that do not meet current safety standards. They may also suffer from ageing and deterioration induced by environmental factors such as corrosive agents and earthquakes. A methodology has been developed to assess the current state of existing structures using vibration-based structural health monitoring. This technique has attracted civil engineering community recently. Vibration-based, non-destructive damage identification uses changes in the dynamic characteristics of the structure to identify damage. Full or large-scale dynamic tests of structural specimens provide unique opportunities to evaluate and validate these methods under realistic conditions, i.e. with the same level of measurement noise, estimation uncertainty and modelling errors, which are observed as in situ conditions. In this paper, we have studied the behaviour of existing structures and the models casted in the lab. Experimental determination of the dynamic characteristics of the model of RCC building under different levels of damage has been used to develop correlation between damage in the models of RCC buildings with its known dynamic characteristics using artificial neural network models.

In the design of reinforced concrete structures, much of the attention is embarked towards calculation of the strength of basic structural elements like beams, columns and slabs. Comparatively lesser emphasis has been laid on the detailing, corresponding strength and behavior of corner joints, especially those subjected to opening moments as in the case of cantilever retaining walls, bridge abutments, channels, rectangular liquid retaining structures, beam column joints under earthquake loads. The detailing of reinforcement should be easier and simpler in order to expedite the construction process. At the same time structural member should satisfy the fundamental requirements of strength expressed in terms of controlled cracking and ductility. The result of a comprehensive experimental programme to evaluate the structure behavior of opening corners having U type detailing; corners reinforced with fibers is presented in this paper. The parameters of investigation are: strength measured in terms of joint efficiency, ductility, and crack control. A substantial increase in post-cracking tensile strength, ductility and crack control can be achieved by adding steel fibers to the concrete. Therefore U type detailing system investigated previously was tested afresh with crimped-type flat steel fibers having aspect ratio of 30 and 50 at different percentage volume fractions of 0.5%, 1.0%, 1.5% and 1.75%. The investigations indicate that in the specimen, there is a 30%-35% gain in efficiency with increase in volume fraction up to a certain limit beyond which there is a drop in mix workability and joint efficiency.

In the past few years, there has been growing use of finite element method for analysis of RCC structures to eliminate the expensive testing. However, validations of numerical models are instrumental towards making models reliable, which is, fundamental towards truly predictive prototyping. Keeping this in view, paper presents the results of numerical study of Reinforced Concrete Corners under opening moments using general-purpose finite element analysis software (ANSYS) and the comparison of results to the experimental results available in the literature [Singh and Kaushik, J Inst Eng (India), 84:201–209, 2003]. The Load deflection behaviour obtained is compared with the results corresponding to four different reinforcement detailing investigated experimentally [Singh and Kaushik, J Inst Eng (India), 84:201–209, 2003]. Details of the FE modeling of Reinforced Concrete Corners with four different reinforcement detailing have been presented. The best reinforcement detailing of Reinforced Concrete Corners on the basis of load deflection behaviour has been judged and advocated further on the basis of finite element analysis. The second phase of the study, investigates the effect of diameter of main steel, grade of concrete and spacing of shear reinforcement on load deformation behavior of the corners under opening bending moments.

In the present study, the non-linear response of RC frame using FE modeling under the incremental loading has been carried out in the first phase of analysis to study the response and load-carrying capacity of a four storeyed RC frame using non-linear finite element analysis. In the second phase of study an analysis model for retrofitted RC frame using finite element method using software ATENA is presented. The results obtained from FE analysis in both cases are compared with the experimental data for four storeyed RC frame tested by BARC at CPRI. The results from finite element analysis were calculated at the same location as used in experimental test. The accuracy of the finite element model is assessed by the comparison with experimental results which are to be in good agreement. The base shear/ displacement curves from finite element analysis agree well with the experimental results in linear range. The maximum difference in base shear is observed to be 7.9%. I. Introduction In order to evaluate the margin of safety of RC structures against failure an accurate estimation of the ultimate load is very important and the project of the load-deformation behavior of the structure throughout the range of elastic and inelastic response is desirable.There are various factors which are accountable for these deteriorations, such as increasing load, corrosion of steel, earthquake, environmental effects and accidental impacts on the structure. The increase in scale of modern structures is closely related to the extent and impact of disaster in terms of human and economical loss in the happening of structural failure (1). As a result, careful and detailed structural safety analysis becomes more and more crucial. The purpose of such an analysis is the investigation of the behavior of the structure under all probable loading conditions, both, monotonic and cyclic The static pushover analysis is becoming a common tool for seismic performance assessment of existing and new structures. The pushover analysis provides adequate information on seismic demands imposed by the design ground motion on the structural system and its components. The purpose of pushover analysis is to evaluate the projected performance of structural systems by estimating performance of a structural system by estimating its strength and deformation demands in design earthquakes by means of static inelastic analysis, and comparing these demands to available capacities at the performance levels of interest. The inelastic static pushover analysis can be viewed as a method for predicting seismic force and deformation demands, which accounts in an approximate manner for the redistribution of internal forces that no longer can be resisted within the elastic range of structural behavior (2). Up-gradation of reinforced concrete structures is required for many different reasons. The concrete may have become structurally inadequate for example, due to deterioration of materials, poor initial design and/or construction, lack of maintenance, upgrading of design loads or accidental events such as earthquakes. That's why repair and rehabilitation has become an increasingly important challenge for the reinforced cement concrete structures in recent years. The major goals of the retrofitting are to strengthening the retrofitted structures for life safety and the protection of the structures. The existing deficient structures are retrofitted to improve their performance in the event of any natural disaster and to avoid large scale damage to life and property. Evaluation of behaviour of structures after retrofitting is more important. 1.1 Importance and Historical Background of Finite Element Modeling The complicated analytical modeling of the complex behaviour of reinforced concrete in its non-linear zone has led engineers in the past to rely heavily on empirical formulas which were derived from numerous experiments for the design of reinforced concrete structures. The finite element method makes it achievable to take into account the non-linear response. Finite element method of analysis has become a powerful computational tool with the introduction of digital computers, which allows complex analyses of the nonlinear response of RC structures to be carried out in a regular mode. Though FEM is useful for obtaining the load

Tall buildings cater to the need for increased workspace with a reduced footprint, enhance the skyline, and image and increase the prestige of a city. Tall buildings also tend to intercept upper level high velocity winds and deflect them down to ground level, giving rise to conditions that could be unpleasant or even dangerous to pedestrians. Such accelerated winds also reduce the appeal of plazas, outdoor cafes, parks and pedestrian access-ways. Vertically accelerated downward wind flows can be mitigated with the help of architectural elements like podia or, canopies. Horizontally accelerated flows are best ameliorated with soft and hard landscape elements such as trees, shrubs and porous fences. This paper reports results of wind tunnel investigations that have been carried with the objective of assessing the role of landscape elements in moderating the pedestrian level wind environment in the vicinity of tall buildings. The tests have been carried out in the de Bray boundary layer wind tunnel at the University of Auckland on a representative model of a tall building suburb in New Delhi using the erosion technique enhanced with an image processing system. The results of the tests have brought out the effectiveness of landscape elements such as trees and porous fences in mitigating adverse horizontal winds in the vicinity of tall buildings.

PurposeIn developing countries such as India, it is common practice to use low‐quality building materials, the strength of such materials reduce with time, which affects the lifespan of buildings. The wind, rain, seepage, and surface runoff are other key factors responsible for building damage and exterior degradation. The increasing industrial growth in and around urban areas is responsible for increasing industrial and anthropogenic emissions that are found to accelerate degradation of the buildings that affects their physical appearance. In an area prone to natural hazards such as earthquakes, volcanoes, subsidence, floods, lightning, tornados, and cyclone/hurricanes, huge amounts of damage throughout the globe has been experienced. For the purpose of assuring safety due to natural hazards, it is necessary to monitor the damage for its existence, its location and extent. Undetected damage may potentially lead to risk of vulnerability caused by natural hazards and eventually to catastrophic failure. Hence, rapid structural damage detection is essential and important to save human life due to failure of structures or buildings. Most of the time, human loss occurs due to damage to the buildings. This paper aims to address these issues.Design/methodology/approachIn the present study, numerous experiments have been carried out on two reinforced concrete building test specimens and on seven existing reinforced cement concrete structures.FindingsThe results presented here in this study show that the vibration measurements can be used to monitor the health of framed reinforced cement concrete buildings.Originality/valueThe present study is part of doctoral thesis of Varinder S. Kanwar, an original research work.

An efficient and highly sensitive fiber Bragg grating optical sensor is demonstrated to detect strain and corrosion in civil structures. The sensitivity of the fiber Bragg grating optical sensor is enhanced after examining different grating shapes, grating lengths, and refractive indexes of the core. The experimental results show that the proposed uniform grated fiber Bragg grating with 1.46 refractive index and 50,000 μm grating length provides better sensitivity in terms of wavelength shift (approximately 3 nm). The theoretical results are also compared with the experimental results for validation, and it is observed that the proposed sensor can monitor strain/corrosion with high sensitivity and speed.

Purpose – The need for structural health monitoring systems is continuously growing to maintain existing civil infrastructure. For the purpose of assuring seismic safety, it is necessary to monitor the damage for its occurrence, its location and the extent of damage. Information on the damage may be utilized to make decisions on maintenance and structural safety of existing buildings, rapid evaluation of condition of damaged structure after future earthquakes, estimation of residual life of structures, feasibility of repair and retrofitting of structures, partial replacement or demolition of structure and financial planning for renovation and rehabilitation. The purpose of this paper is to present a four‐level scheme of damage detection.Design/methodology/approach – In the first stage of the four‐level scheme, finite element model has been developed and dynamic parameters are calculated. In the second stage, change in the dynamic properties of farmed reinforced concrete building model is identified from v...

A structure is evaluated, after an earthquake, to find out whether it is usable or requires repair and retrofitting. The natural time period, damping, and mode shape are the primary dynamic characteristics of any structure that is related to seismic forces during an earthquake event. Periodic monitoring using vibration measurements is one of the most effective nondestructive methods to identify the damage level. A significant deviation in natural frequencies or damping ratios from the undamaged states indicates the possible occurrence of damage. In the present study, the dynamic characteristics of a 2D rigid frame of a reinforced concrete building are obtained analytically under different levels of damage. Further, using an artificial neural network (ANN) model the authors have developed a correlation between the damage in the frame of the reinforced concrete building with its known dynamic characteristics. Use of such correlations for evaluating the health status of the buildings has been discussed.

Artificial Neural Networks (ANN) have the capability to develop functional relationshipsrnbetween input-output patterns obtained from any source. Thus ANN can be conveniently used to developrna generalised relationship from limited and sometimes inconsistent data, and can therefore also be appliedrnto tackle the data obtained from wind tunnel tests on building models with large number of variables. Inrnthis paper ANN model has been developed for predicting wind induced pressures in various zones of arnGable Building from limited test data. The procedure is also extended to a case wherein interference effectsrnon a gable roof building by a similar building are studied. It is found that the Artificial Neural Networkrnmodelling is seen to predict successfully, the pressure coefficients for any roof slope that has not beenrncovered by the experimental study. It is seen that ANN modelling can lead to a reduction of the windrntunnel testing effort for interference studies to almost half.

Tall building can vibrate in both the directions of Along wind and Across wind caused by the flow of wind. Modern Tall buildings designed to satisfy lateral drift requirements, still may oscillate excessively during wind storm. These oscillations can cause some threats to the tall building as buildings with more and more height becomes more vulnerable to oscillate at high speed winds. Sometimes these oscillations may even cause discomfort to the occupants even if it is not in a threatening position for the structural damage. So an accurate assessment of building motion is an essential prerequisite for serviceability. The wind response on tall buildings is generally estimated either through wind tunnel testing or using analytical approach as mentioned in IS8751987, Part-3. However, both these methods are very cumbersome and time consuming. Therefore, in this paper an attempt has been made to estimate the wind response on tall buildings using Genetic Programming in the along wind direction for Long After Body and Short After Body. The database has been developed using the analytical approach as given in IS875-1987, Part-3. The building height, plan dimensions, design wind speed, gust factor and base moment have been used as the parameters for the development of the equations. The Gust Factor and Base Moment thus obtained from Genetic Programming have been thus compared with the analytical values.

The effect of strain on civil structures is experimentally studied using fiber Bragg grating (FBG). The genetic algorithm is implemented to optimize the multiple parameters (Poisson’s ratio, photoelastic coefficient P11, and photoelastic coefficient P12) of the proposed sensor. The optimized results helped in increasing the sensitivity in terms of wavelength shift. It is observed that the proposed FBG provides maximum wavelength shift of 38.16 nm with Poisson’s ratio of 1.94, photoelastic coefficient P11 of 1.994, and photoelastic coefficient P12 of 1.8103.