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  • 1.
    Al-Taie, Entidhar
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Saaed, Tarek Edrees
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Foundation assessment in different parts of Iraq using STAAD Pro v8i2013In: Journal of Civil Engineering and Architecture, ISSN 1934-7359, E-ISSN 1934-7367, Vol. 7, no 3, p. 273-281Article in journal (Refereed)
    Abstract [en]

    Foundation is considered as one of the main parts of any structure such as buildings, railways, bridges, etc. The type of foundation used is highly dependent on the type and properties of soil. The design of foundations requires many factors that should be defined such as the load that the foundation is going to hold, geological conditions of the soil under the foundation, type of soil and the local building code criteria.There are number of differences in the geological and soil conditions in Iraq. As a consequence, these differences are reflected on the type of foundation to be used. Despite these differences, same materials and style of buildings are used all over Iraq. The main problems of Iraqi soil are high gypsum content, salinity and shallow water table depth. These factors that influence the foundations are the soil properties and the amount of loads that transmitted by the superstructure.The situation had been analysed through a case study which illustrated the link between soil and foundation types in three different parts of Iraq (Mosul, Baghdad and Basra). One building was analysed using STAAD. Pro software in these regions. It is evident that Iraqi designers and engineers require local code to define all the loads, materials and design of the foundation to be used. The use of local materials might be very effective from both engineering and economic perspectives.

  • 2.
    Edrees, Tarek
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Structural Control and Identification of Civil Engineering Structures2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In general, the main purpose of a structural control system is to apply powerful control techniques that improve the behaviour of civil structures under various kinds of dynamic loading. The first part of this thesis presents novel applications of posicast and input shaping control schemes that have never previously been applied in the field of structural control. Numerical simulations of a benchmark three-story building with an MR damper are used to verify the efficiency of the proposed control theories. The superiority and effectiveness of the suggested schemes at reducing the structure’s responses were demonstrated using six evaluation criteria and by comparison to results achieved with well-established classical control schemes. Moreover, a comprehensive procedure for generating scaled real ground motion records appropriate for a seismic analysis and design of structures using the linear spectrum matching technique is presented based on a seismic hazard study.To efficiently control a structure, it is necessary to estimate its real-life dynamical behaviour. This is usually done using the Structural Identification approach, which is also addressed in this thesis. Structural Identification is commonly utilized to bridge the gap between the real structure and its modeled behaviour. It can also be used to evaluate the structure’s health, detect damage, and assess efficiency. Despite the extensive development of parametric time domain identification methods, their relative merits and the accuracy with which they predict the behaviour of vibrating structures are largely unknown because there have been few comparative studies on their performance under diverse test conditions, and they have not been verified against real-life data gathered over extended periods of time.Thus, the second part of this thesis focuses on applications of parametric and non-parametric models based on the Structural Identification approach in order to clarify their potential and applicability. In addition, a new strategy is proposed that combines this approach with techniques based on Singular Value Decomposition (SVD) and Complex Mode Indicator Function (CMIF) curves to detect structural damage.The methods developed in this work are used to predict the vertical frequencies of the top storey in a multi-storey building prefabricated from reinforced concrete in Stockholm, and to detect and locate damage in a benchmark steel frame. In addition, the non-parametric structural identification approach is used to investigate variation in the modal characteristics (frequency, damping, and mode shapes) of a steel railway bridge.

  • 3.
    Edrees, Tarek
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Structural Identification of Civil Engineering Structures2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The assumptions encountered during the analysis and design of civil engineering structures lead to a difference in the structural behavior between calculations based models and real structures. Moreover, the recent approach in civil engineering nowadays is to rely on the performance-based design approaches, which give more importance for durability, serviceability limit states, and maintenance.Structural identification (St-Id) approach was utilized to bridge the gap between the real structure and the model. The St-Id procedure can be utilized to evaluate the structures health, damage detection, and efficiency. Despite the enormous developments in parametric time-domain identification methods, their relative merits and performance as correlated to the vibrating structures are still incomplete due to the lack of comparative studies under various test conditions and the lack of extended applications and verification of these methods with real-life data.This licentiate thesis focuses on the applications of the parametric models and non-parametric models of the System Identification approach to assist in a better understanding of their potentials, while proposing a novel strategy by combining this approach with the utilization of the Singular Value Decomposition (SVD) and the Complex Mode Indicator Function (CMIF) curves based techniques in the damage detection of structures.In this work, the problems of identification of the vertical frequencies of the top storey in a multi-storey¸ building prefabricated from reinforced concrete in Stockholm, and the existence of damage and damage locations for a bench mark steel frame are investigated. Moreover, the non-parametric structural identification approach to investigate the amount of variations in the modal characteristics (frequency, damping, and modes shapes) for a railway steel bridge will be presented.

  • 4.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Identification of building damage using armax model: A parametric study2016In: Diagnostyka, ISSN 1641-6414, Vol. 17, no 3, p. 3-14Article in journal (Refereed)
    Abstract [en]

    The Structural Identification approach is used to identify and localize the existence of damage for a steel frame. The black box linear parametric model called Auto-Regressive Moving Average with eXternal input (ARMAX) was utilized for the construction of the Frequency Response Functions, based on simulation results. The Singular Value Decomposition method was adopted to identify how many significant eigenvalues exist and plot the Complex Mode Indicator Function for the complete frame. Three damage indices were adopted to evaluate the state of damage in the frame. The results indicated that the ARMAX is a robust scheme for structural damage detection.

  • 5.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Posicast Control of Structures Using MR Dampers2016In: Structural Control and Health Monitoring: The Bulletin of ACS, ISSN 1545-2255, E-ISSN 1545-2263, Vol. 23, no 8, p. 1121-1134Article in journal (Refereed)
    Abstract [en]

    In this article, a novel application of a semi active Posicast control scheme for structures with Magneto- Rheological (MR) dampers is presented. MR dampers are considered to be highly promising of semi-active control systems, which are becoming increasingly popular for alleviating the effects of dynamic loads on civil engineering structures because they combine the merits of both passive and active control systems. The main contribution of this article relates to the design, application, tuning and performance evaluation of the novel Posicast control scheme for structural control. The efficiency of the suggested control strategy was evaluated by performing numerical simulations of a benchmark three-story building with an MR damper, rigidly attached between the first floor and the ground. The damper’s behaviour was simulated using the Bouc-Wen model. Seven evaluation criteria were used to assess the performance of the proposed posicast control scheme in reducing the excited structure’s responses to dynamic loading. The simulation’s results indicated that the Posicast control scheme had significant advantages over conventional alternatives in terms of performance and efficiency.

  • 6.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. College of Engineering, Department of Civil Engineering, University of Mosul, Mosul, Iraq.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Dritsas, Leonidas
    University of Patras, Department of Electrical Engineering.
    Semi-active control of flexible structures using closed-loop input shaping techniques2017In: Structural Control and Health Monitoring: The Bulletin of ACS, ISSN 1545-2255, E-ISSN 1545-2263, Vol. 24, no 5, article id e1913Article in journal (Refereed)
    Abstract [en]

    In this research effort, a novel approach on the control of structures with magnetorheological (MR) dampers is presented, based on an appropriately adapted closed-loop version of the generic input shaping control theory. The MR damper is a very promising kind of semi-active control system (actuator), mixing the advantages of the active and passive structural control systems, hence their increasing use as attenuators that reject the effects of dynamic loads on civil engineering structures. The main contribution of this article is the application and performance evaluation of the novel ‘Linear Matrix Inequality-based’ feedback version of the input shaping control theory for the first time in the area of structural control. The need for the use of a feedback version of input shaping control stems from the design trade-off between robustness and speed of response requirements. A simulation of a benchmark three-story building with one MR damper is employed to verify the efficiency of the proposed control approach. The nonlinear behaviour of the MR damper, rigidly connected between the first floor of the structure and the ground, is captured by the well-known Bouc–Wen model. The superiority and effectiveness of the proposed scheme in reducing the responses of the structure were proved using seven quantifiable evaluation criteria and by comparing these results with those achieved by classical and well-established alternative control schemes.

  • 7.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Grip, Niklas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Investigation of changes in modal characteristics before and after damage of a railway bridge: A case study2015In: The IES Journal Part A: Civil & Structural Engineering, ISSN 1937-3260, E-ISSN 1937-3279, Vol. 8, no 2, p. 131-144Article in journal (Refereed)
    Abstract [en]

    The linear, time-invariant transfer function Txy has been utilized for the construction of FRF, based on the ambient vibration measurements. The results presented here indicated the possibility to identify and localize damages in steel railway bridges from the variations in the modal characteristics of the structure. The comparison between the modal characteristics for the healthy and collapsed bridge confirmed that damage had been existed. The abnormal percentage of change in modal damping, between the healthy and any other condition for a structure, can be regarded as a serious indicator for early stages of damage, while the high percentage of change in modal damping can clearly indicate the existence of damage in that structure. The average ratio of change in the damping ratio from the healthy to the collapsed bridge was about 206 % and this ration could be regarded as an index for the existence of a serious damage in steel bridges, which needs further evaluation in other test cases.

  • 8.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    A comparative study on the identification of building natural frequencies based on parametric models2014In: Proceedings of the 33rd IASTED International Conference on Modelling, Identification and Control: February 17 – 19, 2014, Innsbruck, Austria, 2014Conference paper (Refereed)
    Abstract [en]

    The analysis and design of civil engineering structures is a complex problem, which is based on many assumptions to simplify these operations. This in turn, leads to a difference in the structural behaviour between calculations based models and real structures. Structural identification was proposed by many researchers as a tool to reduce this difference between models and actual structures. Moreover, Parametric models and non-parametric models were used intensively for system identification by many researchers. In this research effort, the system identification concept is utilized to identify the natural frequencies for a steel building’s frames. Different black box linear parametric models such as Transfer Function model (TF), Auto-Regressive model with eXternal input model (ARX), Auto-Regressive Moving Average with eXternal input (ARMAX) model, Output Error model structure (OE), and Box-Jenkins model (BJ) were examined for identifying the first 10th natural frequencies for the building’s frames, based on simulation results. Abaqus 6.12 finite-element software was utilized to perform the time history analysis for the examples and the obtained responses at one point of the roofs (assumed as a sensor) were further processed by the parametric models to obtain the building’s natural frequencies based on the Abaqus time history analysis results (assumed as a measurements). After that, Abaqus 6.12 was utlized again to perform another analysis, which is called frequency analysis to obtain the building’s natural frequencies and mode shapes based on the stiffness and mass (not the measurements) of the buildings. The results showed that the linear parametric models TF, ARX, ARMAX, OE, and BJ are robust to identify the natural frequencies of building and they are recommend for future work.

  • 9.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Comfort Level Identification for Irregular Multi-storey Building Subjected to Vibrations2015In: Automation in Construction, ISSN 0926-5805, E-ISSN 1872-7891, Vol. 50, p. 40-49Article in journal (Refereed)
    Abstract [en]

    In this article, the System Identification approach is being used to identify the vertical frequencies of the top storey in a multi-storey building prefabricated from reinforced concrete in Stockholm. Before building construction, detailed investigation indicated that the building will not be affected by train vibrations from the nearby railway yard. After building completion, disturbing vibrations were observed in the building. Three measurement types namely: ambient vibration test, forced vibration test on the rails, and forced vibration test have been performed in order to specify the probable reasons for these vibrations. Five methods of structural identification approach, specifically: ARX, ARMAX, BJ, OEand State Space Models have been implemented for the identification process in this study usingthe tests' results. All the test types and model structures utilized have identified a concentration inthe floor only, which is close to the frequencies of human body parts. Furthermore, the article concludes that the ARMAX model and the Output Error model have indicated an excellent performance to predict the mathematical models of vibration's propagation in the building, when compared with other models used from the three types of tests. In addition, the results of the aforementioned system identification methods, implemented for this study, have indicated that there are no other reasons for the disturbing vibrations still observed in the building. Furthermore, the results confirmed the correctness of the previous theoretical and experimental results obtained by different specialists, who stated that the values of floor acceleration are within the acceptable limits, and the probable reason for any disturbance is the resonance between the generated low frequencies and the human body parts’ frequencies.

  • 10.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Semi-active structural control strategies2014In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 31-34Article in journal (Refereed)
    Abstract [en]

    The utilization of structural control systems to alleviate the responses of civil engineering structures, under the effects of dynamics loadings, has become a standard technology, while still there are numerous of current research approaches for advancing the effectiveness of these methodologies. It is important for successful application of smart structure to provide an effective control algorithm to compute the control forces to be applied on the building in order to reduce the external disturbances. The aim of this article is to provide a review of the control strategies to control the performance of semi-active systems utilized in civil engineering structures.

  • 11.
    Edrees, Tarek
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jonasson, Jan-Erik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Hedlund, Hans
    Skanska Sverige AB Technology, Bridge and Civil Engineering.
    A state-of-the-art review of Structural Control Systems2015In: Journal of Vibration and Control, ISSN 1077-5463, E-ISSN 1741-2986, Vol. 21, no 5, p. 919-937Article in journal (Refereed)
    Abstract [en]

    Nowadays the utilization of structural control systems for alleviating the responses of civil engineering structures, under the effects of different kinds of dynamics loadings, has become a standard technology, while still there are numerous of current research approaches for advancing the effectiveness of these methodologies. The aim of this article is to review the state of the art technologies in structural control systems by introducing a general literature review for all the types of vibrations control systems that have been appeared till now. These systems can be classified into four main groups: a) passive, b) semi active, c) active, and d) hybrid based on their operational mechanism. A brief description of each of these main groups and their subgroups, with their corresponding advantages and disadvantages will be also extendedly reported in this review. This article will conclude by providing an overview of some innovative practical implementations of devices, which are able to demonstrate their potentials and future directions of structural control systems in civil engineering.

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