Nouredine Bourahla

Ecole Nationale Polytechnique Algiers · Civil Engineering Department

In practice, assessing the structural integrity of existing structures with complex forms poses a challenge. Although photogrammetry has gained increasing recognition as a versatile and cost-effective technique for obtaining numerical three-dimensional models, it still presents some difficulties in converting the scanned models into exploitable fin...

This paper presents a dual-modified implicit time integration method (DMITIM) for three-dimensional impact modelling within the framework of the scaled boundary finite element method (SBFEM). Controlled by a single parameter, this method effectively dissipates high-frequency responses in impact problems without affecting low-frequency responses, en...

This paper introduces a neural network-based methodology for determining the total floor eccentricity along one axis in existing buildings. The method utilizes ambient vibration-measured natural frequencies and corresponding frequency response amplitudes at two distinct points on the considered floor. The developed feed-forward neural network takes...

While significant advancements have been made in structural health monitoring (SHM), effectively implementing emerging techniques for damage detection and localization in large civil engineering structures remains a challenge. This paper demonstrates a comprehensive multi-damage detection framework based on a deep neural network (DNN) using a case...

Predicting the propagation of ground vibration wave, induced by highways, railways, electrical power plants and other industrial activities, in their vicinity is of paramount importance to evaluate the degree of nuisance to populations, buildings and sensitive equipment. The present study proposes a generalized artificial neural network (ANN) model...

This paper proposes an approach for evaluating the seismic performance of buildings. By considering the uncertainties in material and geometrical properties of the structural elements as well as those related to the seismic loading, this method aims to delimit the performance zone of the structure rather than focusing on a single performance point...

This paper proposes an improved vibration-barrier technique to reduce the vibrations of shallow foundations. For this purpose, three-dimensional finite element with absorbing boundaries were used to model and perform dynamic analyses of the whole system comprising the soil, the in-filled trenches (barrier) and the foundation. The barriers are commo...

Knee bracing system is a lateral earthquake resisting system which combines the feature of lateral stiffness and energy dissipation capacity. The concept relies on the strategic placement of hysteresis dissipative elements to yield (form plastic hinges) in the first instance and absorb energy to protect the main frame. This paper proposes an intell...

In line with the trend towards predictive seismic codes adopting the performance-based design method, this paper presents an integrated protocol to determine the degraded hysteresis parameters of corroded RC hinges based on relationships developed for this purpose together with a calibration procedure using the random-mutation hill-climbing algorit...

To keep pace with the trend of automating structural design processes, this paper presents an intelligent framework for generating optimized reinforced concrete dual systems (RCDS) based on given architectural configurations extracted in IFC format, allowing seamless integration with a BIM platform. First, a technique is developed to reduce the inf...

This paper proposes an improved vibration-barrier technique to reduce the vibrations of shallow foundations. For this purpose, three-dimensional finite element with absorbing boundaries were used to model and perform dynamic analyses of the whole system comprising the soil, the in-filled trenches (barrier) and the foundation. The barriers are commo...

RESUME Cet article présente une stratégie de surveillance de l'état de santé structurale appliquée à la Kalaa de Beni-Hammad (Algérie), monument historique millénaire. La procédure consiste à optimiser le nombre et les emplacements des capteurs et d'appliquer une méthode hybride utilisant un RNA pour la détection des dommages et leurs sévérités à p...

The trend in systemization and automation of the design process in the architecture, engineering and construction (AEC) industry is relatively slow because of the diversity of partners, the specificity of each project and the iterative nature of the design. Cold-formed steel structures which are widely used as a construction system, lends itself we...

Pushover analysis technique is a key tool for the performance-based seismic design that has been largely adopted in the new generation of seismic codes. Therefore, more precise and reliable performance predictions are highly demanded. Improved upper-bound (IUB) pushover analysis is one of the advanced nonlinear static procedures (NSPs) that has bee...

This paper presents an experimental program carried out to investigate the behavior up to failure of composite wood-cold-formed steel studs under monotonic and cyclic axial loading. The composite stud is made of a wood core incorporated inside a CFS C-channel. The main objective of the experiments is to quantify the ultimate strength, the energy di...

Pushover analysis technique is a key tool for the performance-based seismic design that has been largely adopted in the new generation of seismic codes. Therefore, more precise and reliable performance predictions are highly demanded. Improved upper-bound (IUB) pushover analysis is one of the advanced nonlinear static procedures (NSPs) that has bee...

From structural and material point of view each historic monument is a textbook case, as it differs in shape, age, material characteristics and level of preservation. New means and approaches are used for geometric and shape survey, material and modal characterization, which helps restitute detailed information regarding the structural elements of...

Purpose Despite the fast progress in structural health monitoring (SHM), the efficient use in practice of emerging techniques for large civil engineering structures is still a challenge. This paper outlines a practical framework to optimize both the number and the locations of sensors to measure frequency response functions (FRFs) that will be proc...

This paper presents a practical procedure based on a hybrid neural network-flexibility damage index technique to predict the severity level and location of damages in a gravity dam. Numerical models of the Beni-Haroun gravity dam in Algeria are elaborated and validated using ambient vibration tests. The measured frequency response functions are use...

This paper presents a novel approach to determine the seismic performance of a building, taking into account the uncertainties in material and geometrical properties of the structural elements as well as those related to the seismic loading. The elaborated procedure is applied to a building case, where it has been found that the performance point l...

This paper evaluates the performance of a genetic algorithm (GA) in generating an optimal RC shear-wall slab structure for a given architectural model in IFC (Industry Foundation Classes) format. The concept of the optimization procedure is first outlined. Then a sensitivity analysis is carried out to find out the adequate weights of the multi-obje...

In recent years, significant economic and human loses have been caused by earthquake events across the globe, particularly in developing countries, where non-seismically designed buildings constitute a significant share of the existing stock. Algeria is one of those cases and has witnessed earthquakes in the northern part of the country, which indi...

Performance evaluation of masonry Infilled RC frame structures under lateral loads Numerous studies on masonry infill panels have greatly contributed to the research of strength, stiffness and energy dissipation capacity of various buildings. If the effects of masonry panels are disregarded, structural damage will occur under any significant ground...

In this paper, the effect of openings on global performance of Cold Formed Steel Shear Wall Panels is investigated numerically using the ABAQUS software. A benchmark model is first validated in terms of lateral shear capacity and nonlinear behaviour of the CFS-SWP. The failure mode of the CFS-SWP with opening is identified and validated. Subsequent...

Shaking tables are an essential tool in dynamic testing to analyse the nonlinear behaviour of structures, structural and non-structural elements, evaluate and predict their seismic responses to dynamic excitations similar to real earthquakes. A high fidelity in signal reproduction on the shaking table platforms, achieved by a robust control system,...

The prediction of the nonlinear seismic demand for a given hazard level is still a challenging task for seismic risk assessment. This paper presents a Ground Motion Prediction Model (GMPE) for efficient estimation of the inelastic response spectra of 5% damped Single Degree of Freedom (SDOF) systems, with Elastic-Perfectly-Plastic hysteretic behavi...

Replicating acceleration time histories with high accuracy on shaking table platforms is still a challenging task. The complex interference between the components of the system, the inherent nonlinearities, and the coupling effect between the specimen and the shaking table are among other reasons that most affect the control performance. In this pa...

The objective of this paper is to validate finite element (FE) modeling protocol for screw connected, back-to-back built-up cold-formed steel (CFS) columns. The protocol is developed and validated using results from previously conducted experiments. The effort is motivated by two applications: (1) to augment experimental findings on built-up CFS co...

The frequency band gaps concept is commonly employed in many fields of physics. Recently, the concept is extended to other disciplines such as seismic vibrations. This article explores the potential of an approach based on periodic arrays to protect a civil engineering structures from seismic effects. The principle consists of an arrangement of per...

This paper addresses a recently proposed novel method to automatically derive an optimized structural layout for a given architectural design in IFC (Industry Foundation Classes) format extracted from a BIM (Building Information Modeling) model. The procedure is based on the idea of converting the civil engineer conceptual design into a multi-objec...

RÉSUMÉ. Les grands ouvrages tels que les barrages, sont considérés comme vitaux et sont souvent exposés à des conditions environnementales très sévères comme les secousses sismiques. Les méthodes de surveillance basées sur les analyses vibratoires utilisent les paramètres modaux (fréquences, déformées propres, coefficients d’amortissement) qui dépe...

In this paper, a new nonlinear static analysis procedure is proposed to assess the seismic performance of tall buildings, which considers both the higher modes effects as well as the progressive changes in the dynamic characteristics of structures during the inelastic response. In this method, the applied load pattern computed using the upper-bound...

This paper proposes an innovative approach based on a genetic algorithm able to automatically derive an optimal structure for a given architectural configuration in IFC format or BIM platform. The concept is based on a multi-objective optimization process that randomly generates an initial population of potential structural configurations which com...

Most of the research work on the torsional effect of the accidental eccentricity has been based on single-storey building models. Although the accidental eccentricity parameter is expressed for each individual floor, but the overall torsional behaviour of a multi-storey building can be significantly different from that of a single-storey model. In...

The aim of this research is to assess the seismic performance of reinforced concrete columns under different axial load and transverse reinforcement ratios. These two parameters are very important as for the ductility, strength, stiffness, and energy dissipation capacity for a given reinforced concrete column. Effects of variable axial load ratio a...

The seismic performance of reinforced concrete columns subjected to various levels of axial load is assessed in the paper. An equation relating the confined region to the applied axial load is proposed and compared to the Algerian seismic code RPA99/V2003 specifications, based on the concrete spalling length measured on 16 specimens under different...

The concept of frequency gaps in phononic crystals is widely used in physics. The feasibility and efficiency of applying this principle in damping out seismic and mechanical induced vibrations in real scale of civil engineering constructions are presented in this article through the results obtained from numerical modeling and analysis of a concret...

This paper presents a numerical evaluation of the shear strength of Cold Formed Steel Shear Wall Panels (CFS-SWPs) having 1.33:1 and 1:1 height-to-width aspect ratios with 0.76 mm steel plate sheathing thickness and 1:4, 1.33:1 and 1:1 height-to-width aspect ratios with 0.46 mm steel plate sheathing thickness, which are not provided by AISI S400. F...

In earthquake engineering practice a number of parameters are proposed to characterize the ground shaking according to multiple aspects: Amplitude, duration and frequency content-based parameters. The mean period parameter (Tm) of a ground shaking is considered as a simplified parameter to describe the frequency content. The aim of this paper is to...

Monitoring the behavior of strategic structures such as high-rise buildings, large bridges and dams is essential to determine their "state of health". Vibration analysis, for preventive maintenance, is a relevant tool that has been used for few decades in this field, relying on correlation between in-situ measurements and finite element model prope...

The Peak Ground Acceleration (PGA) is an important parameter widely used for assessing the earthquake effects at a given site and also for the development of design response spectra for seismic calculation use. The aim of this paper is to predict the PGA and investigate the effect of seismological parameters using feed forward artificial neural net...

Ce papier présente l'application de la méthode SAM (Simplified Analysis of Masonry buildings) pour l'étude du comportement non linéaire des bâtiments en maçonnerie porteuse et montre l'utilité du renforcement par corsetage pour ce type de construction. En premier lieu, les résultats du modèle numérique d'un panneau à deux étages sont confrontés ave...

This paper presents a numerical simulation aimed at analysing the seismic performance of low- and mid-rise cold-formed steel (CFS) framed buildings, employing wood-sheathed shear wall panels (SWPs), designed according to a seismic design procedure compatible with the framework of the Eurocodes. To simulate their nonlinear behaviour, the structures...

In recent years, nonlinear static procedures (NSPs) have gained considerable popularity as an efficient tool in the performance based seismic design practice. This was backed by extensive corroboration studies that have demonstrated its good accuracy in estimating the seismic response of regular structures. Despite the numerous improvements of the...

The concept of frequency band gaps that has been widely used in many disciplines of physics and semiconductors is extended to other phenomena such as seismic vibrations. This paper presents the potential of an approach based on periodic arrays to protect a site from seismic effects. The scheme consists of a periodic arrangement of inclusions that a...

This paper presents the probabilistic seismic performance and risk assessment of cold-formed steel (CFS) sheathed shear wall panel (SWP) structures adopting conventional steel moment-resisting frame (MRF) systems as a benchmark with the aim of exploring the viability of using CFS-SWP as a new structural solution in seismic prone regions. A set of 1...

This paper presents the development of finite element (FE) models for advanced analyses of screw connected and axially-loaded back-to-back, built-up cold-formed steel (CFS) chord studs. Results are validated using column test data from displacement-controlled experiments conducted at Johns Hopkins University. Shell finite element-based models have...

High accuracy and precision in reproducing seismic signals on shaking tables is more and more needed for various applications in structural dynamic testing. However, the distortion between the command signal and the reproduced signal caused by inherent nonlinearities in the system and the nonlinear interaction between the table and the specimen is...

The characterization of ground motion is a fundamental step in seismic analyses of structures subject to earthquake ground acceleration. The seismological parameters affecting the seismic action are not explicitly incorporated in current practice. The aim of this paper is to predict the significant duration and analyze the effects of seismological...

This article proposes a method based on artificial neural networks (ANN) to predict the time history responses at any point on the ground near a shaking table reaction mass (Earthquake Engineering Research Centre, Algiers). The induced vibrations may disturb occupants or damage surrounding buildings. The accelerations generated by the shaking table...

This paper presents the development and validation of a finite element (FE) modeling protocol for screw connected, back-to-back built-up cold-formed steel (CFS) columns using results from experiments conducted at Johns Hopkins University. The shell finite element-based models have been constructed in the ABAQUS FE software and include non-linear ge...

The shaking table is a powerful tool in dynamic testing in which a high signal reproduction fidelity is considered as a distinguishing feature of the system. However, a precise control of the platform motions to ensure desired accelerations is still a challenging target because of the interference of the different mechanical, hydraulic and electron...

A seismic design procedure for CFS structures employing sheathed shear wall panels (SWP), compatible with the framework of the Eurocodes, is proposed in this paper. In order to assess the structural behaviour and generate the required data for the appraisal of the seismic design procedure, the OpenSees finite element environment was used to simulat...

The stability of structures made of light-gauge steel depends highly on the contribution of Shear Wall Panel (SWP) systems under horizontal forces due to wind or earthquake loads. Steel plate sheathing is often used with these panels made of cold formed steel (CFS) to improve its shear strength. In order to predict the shear strength resistance, tw...

Shear wall panels (SWP) are the primary lateral load resisting elements in cold-formed steel (CFS) structures. In this paper, smooth hysteresis models that take into account strength and stiffness degradation, as well as pinching effect have been developed and implemented in OpenSees software, as user-defined uniaxial materials named CFSWSWP and CF...

The seismic codes specify the accidental eccentricity as a percentage (5% or 10%) of the building dimension perpendicular to the direction of excitation, to account for the uncertainties and errors in evaluating the mass and stiffness centres of the building floors and the earthquake rotational component. Because of the random and uncertain nature...

RÉSUMÉ. Les systèmes à masse accordée ou TMD sont des amortisseurs passifs communément utilisés dans des ouvrages de génie civil. La raideur et la masse d'un tel système sont choisies pour que l'oscillateur ainsi constitué dissipe le maximum d'énergie de l'ouvrage qu'on souhaite lui réduire sa réponse dynamique. Un inconvénient majeur, dans la conc...

During the last four decades a great progress has been made in order to understand the effect of earthquakes on dams. The development of measurement instruments which helps to record the response of any structure under actual earthquakes or ambient excitations as well as the progress in analytical procedures led to a better insight of the seismic b...

Cold-Formed Steel low rise buildings have been recently erected in different seismic prone regions in Algeria. The main lateral load resisting system (LLRS) of these buildings is made of shear wall panels (SWP). The latter are composed of CFS C-shaped framing members attached to corrugated steel sheathing using screw connections. The connection bet...

The use of nonlinear static analysis to evaluate the performance of structures subjected to seismic loadings has become widely accepted nowadays in design practice. This is because of its simplicity, reduced time cost and the reliability of the responses compared to nonlinear dynamic analysis. Multi-modal Pushover Analysis (MPA), which takes into a...

Dans la conception sismique des structures en charpente métallique légère à base de profilé formé à froid, une attention particulière est accordée aux systèmes de contreventements. Ces derniers sont des ensembles complexes généralement modélisés par des macro-éléments qui visent à simuler le comportement global en cisaillement.Les tentatives de mod...

In this study, an offline Neural Network (NN) controller is developed as an additional tool to actual shaking table control technique. First, the shaking table is simulated using a finite element model (FE). A second model is implemented as transfer functions in Matlab. Series of dynamic analysis are carried out to constitute a database to train an...

The purpose of producing scaled physical models is to allow the assessment in the laboratory of the probable response of a structure to a prescribed loading. It is obviously of paramount importance to construct these models to reflect reality as accurately as possible. The problem encountered particularly for dynamic testing is that the similitude...

Les panneaux de contreventement en profilés d’acier formés à froid (Cold-Formed Steel « CFS » Shear Wall Panels « SWP »), sont les principaux éléments de contreventement qui résistent aux forces latérales dans les bâtiments en CFS. Leur comportement sismique est géré essentiellement par la performance des éléments de connexion tels que : les élémen...

The design of structures such as buildings, bridges, dams etc. uses often numerical models whose structural and material parameters are assumed from similar projects or limited material tests. For large civil engineering constructions, further validation and checking of the actual as-built construction can be very useful to assess the model accurac...

Shear wall panels (SWP) are the main lateral resisting elements of cold formed steel (CFS) structures. Their seismic behaviour is governed essentially by the performance of the connectors e.g.: sheeting-tosheeting connectors, and sheeting-to-framing connectors. This can be achieved by an acceptable evaluation of the load bearing capacity of the wal...

The seismic codes specify the accidental eccentricity as a percentage (5% or 10%) of the building dimension perpendicular to the direction of excitation, to account for the uncertainties and errors in evaluating the mass and stiffness centers of the building floors. Because of the random and uncertain nature of the factors responsible for the accid...

The equivalent static lateral force method is a simplified technique to substitute the effect of dynamic loading of an expected earthquake by a static force distributed laterally on a structure for design purposes. The total applied seismic force V is generally evaluated in two horizontal directions parallel to the main axes of the building. The eq...

In this paper, a new technique is proposed to confine concrete columns using GFRP-prefabricated bonded shells and a shrinkage-compensating cement mortar. The confinement is performed with three identical shells, each of which contains two stepped lap joints at their ends. The main advantage of this technique is that the shells can be directly assem...

This article addresses the influence of the seismic component of rotation on the torsional response of building structures subjected to earthquake ground motions. Furthermore, the increase an equivalent additional eccentricity due to the action of this component is estimated. For this purpose, a rotational acceleration component is generated from t...