سعد جبار عباس الوزني

The presented study consists of the dynamic analysis of a real pedestrian bridge structure of 35m span over the highway connect Kufa and city center of Najaf (Iraq). The main objective of this analysis was to assess whether the dynamic properties of footbridge structure meets the main safety requirements with the appropriate verification criteria. The extracted dynamic properties of the structural bridge model are natural frequency and mode shape. ANSYS software is used to perform the analysis by ANSYS-APDL method. In this study, the first seven vibration modes of the bridge model are extracted. The dynamic characteristics extracted by modal analysis of the adopted bridge structural model exhibited uncomfortable of vibration modes compared with European standards.

systems using their modal properties is an important tool of Structural Health Monitoring (SHM) of civil infrastructure. The herein presented research proposes procedures for damage detection based on two heuristic optimization methods: Simulated Annealing (SA) and Tabu Search (TS). In order to test the proposed procedures in different frequency ranges, experimental and numerical analyses were conducted on a steel grid bridge model in two configurations, according to the total mass of the structure, as well as for two simulated damage cases. The calibration of model parameters, according to experimentally extracted modal properties, is carried out using the proposed procedures. Numerical computations were conducted using ANSYS package and developed routines under MATLAB environment for model calibration and damage detection procedures. Experimental modal properties were extracted from ambient vibration measurements, as state-of-the art in SHM of complex structures, by the Frequency Domain Decomposition (FDD) technique, using ARTeMIS software. Both of the proposed procedures for model calibration and damage detection, with adopted objective functions including frequency and mode shape differences, exhibit accuracy, efficiency and robustness.

Structural Engineering Department of Faculty of Civil Engineering at University of Belgrade

Present study adopts calibration process based on FE model updating using two heuristics optimizations, Simulated Annealing and Tabu Search methods. A simply supported overhang steel beam model is considered in this study. Experimental and numerical modal analyses are implemented to estimate modal properties using ARTeMIS and ANSYS software, respectively. Results show good convergence between experimentally extracted and numerically updated values of natural frequencies extracted based on ambient vibration measurements.

During recent years, significant effort has been devoted to developing non-destructive techniques for damage detection in structures based on changes of vibration properties. The presented study implemented a simply supported steel overhang beam model. Proposed procedures adopted two heuristic optimization techniques, Tabu search and Simulated Annealing methods used to detect location and extent of damage. Numerical computations were conducted using both ANSYS and MATLAB software, whereas, extraction of the modal properties from ambient vibration measurements, are carried out using ARTeMIS software. Results exhibit that the proposed procedures, with adopted weighting factors, are very efficient to detect position and severity of damage.

This paper presents an overview of the methods of structural damages using the non-destructive testing, as well as the appropriate methods of optimization applied for localization and characterization of the severity of structural damage. Change of stiffness as a result of damage is reflected in the change of modal characteristics of the structure, which is widely used in the detection of defects. Measurement of ambient vibration, with appropriate identification of modal characteristics, are detailed because of the great importance in the process of detection of damage. A key benefit for the application of these methods is the ability to run tests without disturbing the function of structures. Also shown are the basic elements of detection and localization of damage using modern heuristic optimization methods.

The paper presents performance of two different system identification methods applied on experimental ambient vibration recorded data. The first applied method is so-called Frequency Domain Decomposition – FDD, frequency domain based peak-picking method, while the second one is Stochastic Subspace Identification - SSI method, for estimation of state space systems. Emphases are on advantages and disadvantages of both applied methods. Also, application of ARTeMIS software is presented, as a very useful tool to facilitate extracting and displaying modal parameters.

The study presents test and analyses of experimental recorded response from ambient vibration test of the highway bridge in Belgrade across the river Sava. Ambient vibration test carried out on the structure excited by the traffic and wind in order to determine the dynamic structural properties. ARTeMIS software was applied for estimation of structural properties. With a limited number of transducers and available channels, test carried out in a few sets of records with appropriate reference points. Peak-Picking method (FDD) was applied for extraction structural properties of the tested structure.

In the paper, procedure of structural damage detection with application to a simple supported steel beam model, is presented. Simulated Annealing optimization technique is used to determine damaged element by numerical simulation of different scenarios of damage location and severity. The method of damage detection based on changing of dynamics properties of first five natural modes by formulating new objective function. The procedure is done using ANSYS Finite Element Analysis Software, with main optimization routine developed in MATLAB software. The results indicated that the performance of proposed procedure is robust.

The study presents the procedure of simulation of damage detection of simply supported steel beam using Tabu search optimization method. Numerical computation carried out in ANSYS finite element analysis software. Damage detection assumes determination of location and amount of damage. The method uses detection of damage based on changing dynamic properties of structure. The main procedure, using optimization Tabu Search method, is developed in MATLAB package. Damage was successfully detected after performing the procedure for both parameters, location and amount of damage.

The paper studied stresses due to triple axle loads in the interior of a concrete pavement slab resting on elastic foundation, represented by Winkler model, The program was written in Quick BASIC language to handle a problem of calculation of stresses generated inside the concrete pavement slab. The calculation of all parameters which are included and appeared the significant effect on the stresses. Also, the drawing of the stresses charts for many values of load, parameters and thickness of slab are created for this type of triple axle.

Building and Construction Engineering Department-University of Technology

Department of CEng, Faculty of Eng., university of Kufa

The multi-storey buildings and towers that are constructed of steel frames are exposed to lateral loads such as wind loads, earthquakes and explosions, which cause a vibrational movement in the structure. Therefore, the horizontal drift and deformations increase and lead to instability in the structure. So, it is necessary to retrofit the structural steel buildings by increasing the lateral stiffness and ductility of the structure. This is made by choosing a suitable bracing system type to retrofit the building. In this research, the bracing system types are taken to achieve the desired purpose. A summary of this system and its types, and a historical overview of the use of this system were studied. The results are compared by investigating several parameters, such as the total mass of the structure, the cost, lateral stiffness, and lateral displacement. Also, previous research was categorized following how it affected the reinforcement system. The main objectives of the study are to determine the most efficient bracing system for steel buildings under the influence of retrofitting against a lateral load and to compare the structural performance of various types of bracing systems. Also, the outcomes demonstrated that the bracing system decreases lateral displacement and boosts energy dissipation.

Bricks are commonly used in developing regions because of their low cost and ease of accessibility. Buildings built with bricks symbolize Iraq's rich history and represent its rich culture. Those walls will likely fail if in-plane loads are applied to masonry walls without reinforcement. This is particularly due to their insufficient resistance to non-concentric and concentric compression loads. The historical architecture style often relied on using masonry brick; however, brick structures pose challenges when they are exposed to in-plane loading in eccentric loading scenarios, such as in the presence of lateral loads from wind, which can create eccentric compressive forces, especially if the walls are not symmetrically located within the building footprint. Uneven settlement of a building's foundation can introduce eccentricities in the loads applied to the walls. This is particularly relevant in older buildings or structures on uneven or weak soils. During an earthquake, structures experience dynamic loads that can induce eccentric forces and moments in walls, particularly if the seismic forces are not evenly distributed across the building's height or plan. Due to the age of such a structure, some upgrading and strengthening will be necessary. Choosing a strengthening methodology that does not adversely affect the appearance and operation of a building is of paramount importance. Therefore, in recent years, FRP materials have been widely used to address these problems to improve brick masonry walls' structural performance. An FRP material is typically expensive unless applied in a specific configuration for a specific stress condition, but it has many positive characteristics concerning low weight and ease of application. A current study has evaluated the effectiveness of strengthening configurations utilizing FPR materials (CFRP and GFRP) fabricated into sheets and strips in specific orientations. To achieve the objective of this study, eight masonry brick specimens were manufactured and tested until failure occurred. All specimens in each loading condition maintained the same characteristics as the dimensions of the specimen and boundary condition. The specimens of masonry brick were identified with dimensions (813×810mm) according to British Standard BSEN 1052-1: 1999. In eccentric load conditions, the GFRP material has a more significant effect on load, particularly at the cracking stage; however, this effect is less noticeable at the ultimate loading stage. At the concentric load state, the specimens with a GFRP sheet on the entire side and with CFRP in a diagonal configuration present the most significant displacement by (262.8%); moreover, the specimen with a CFRP sheet on the entire side processes the maximum increase in compression stress with (58.8%).

To conduct the vibration based non-destructive evaluation technique of an important historical building of Imam Ali holy shrine, the investigation of structural dynamic behavior is necessary. This study aims to carry out the dynamic (modal) analysis for masonry minaret structure of Imam Ali holy shrine and execute the parametric analysis. The dynamic characteristics, natural frequency and mode shape, are extracted in the modal analysis of the adopted minaret structure. The finite element model masonry bricks minaret is created using ANSYS-software by APDL technique with tetrahedral solid element. The convergence study with different size of mesh (fine, moderate and coarse mesh) to find out the optimum mesh size of FE model is performed. The first seven natural modes are adopted and the first, third, fifth and sixth natural frequency are chosen in the parametric study. In the parametric analysis, four parameters are adopted represent the material properties and the geometry of minaret model. For material properties, Modulus of Elasticity and mass density are selected, whereas the height and radius of minaret model are chosen. The results and relationship of mass density, Modulus of Elasticity, height of minaret and radius of minaret are displayed and discussed. Based on the results, a complete evaluation of the building structure of Imam Ali can be made and the Structural Health Monitoring technique can be implemented. © 2023 American Institute of Physics Inc.. All rights reserved.

A bracing system is the one of effective retrofitting methods for existing high buildings to support the lateral loads. Structural bracings increase the stiffness and stability of the building and the energy dissipation capacity. In this research, the numerical study of retrofitting a multi-story steel building near Imam Ali Holy Shrine in Najaf, Iraq has been conducted. The retrofitting mechanism includes a test of four different bracing systems such as X-bracing, V-bracing, Diagonal-bracing and IV-bracing located in the x and y-axis of the model. The seismic analysis using the elastic response spectrum method was performed for two types of earthquakes, weak and strong. The comparison among different parameters is discussed such as maximum lateral displacement, story drift ratio and base shear values. The seismic load was applied in two axes of the building model simultaneously and the results of the parameters in the x and y-axis were extracted. The results show that the retrofitting using four bracing system types increases the capacity of energy dissipation of the existing building model to seismic load by reducing the maximum lateral displacement in the x-axis by 55%, 44%, 41%, and 30% for X, IV, V and Diagonal-bracing, respectively. However, the X-bracing has a significant increase of the shear base value of the model by%39 and 49% in the x and y-axis, respectively, which means cost-effective compared with the other bracing types. Therefore, the IV-bracing type has an appropriate effect on the strength of the building against seismic load with reasonable cost-effectiveness.

Perforated clay brick masonry is a popular and widely used construction, offering both structural and aesthetic benefits. The structural behavior of perforated clay brick masonry walls is a significant topic in the field of civil engineering. However, understanding the compressive and tensile strength of these walls are influenced by various factors such as the quality of mortar joints, the distribution of mortar, and the presence of reinforcement. The purpose of this study is to investigate the compressive behavior of four perforated clay brick masonry walls, using cement-sand mortar, with two different systems under in-plane compression load. The first masonry system is unreinforced with filling joints, and the other system is reinforced by steel bars embedded in the mortar as a low reinforcement ratio. The study provided valuable arguments about how mortar distribution affects wall performance, which is significantly impacted by poor quality of head joints and the fully or partially distributed mortar in the masonry joints. Also, the role of low reinforcement ratio within the construction industry has important effect. The mentioned parameters are investigated through practical case studies demonstrating their effects in the context of ductility and ultimate load capacity. It was found that the compressive strength of the unreinforced masonry system is highly increased to the distribution of the mortar by 35 % and 133% for filling all holes in brick units and the head joints, respectively, due to increasing the bonding between brick units in the masonry wall specimen. In the reinforced masonry system, the utilization of a low reinforcement ratio is increased the ultimate load capacity by 60% and decreased the ultimate displacement by 54%., but it is no longer provided significant changes to the ductility.

Mass concrete is designed and constructed commonly to avoid early-age cracks, but in some cases, damage is caused by service loads, where machine foundations can be considered as examples of such cases. The present study evaluated the structural performance of the concrete Roller Mill Stand, where cracks were seen after several years of operation. The vertical Roller Mill is one of the main components of a cement plant. The evaluation was based on the following main steps: estimation of the concrete strength, analysis of loading scenarios, structural analysis based on the preceding two steps, and analysis and evaluation of the structure performance. Finite element results showed that cracks were initiated in mill concrete stands when the mill was operated under maximum extraordinary loading case, and then these cracks gradually grew. The field investigation agreed with the numerical analysis that the mill was operated under maximum extraordinary operation conditions, which caused the observed cracks in the reinforced concrete stands. It was concluded that the mass concrete of the stands was strong enough to transfer forces from the mill to the foundation. Also, the compression fatigue failure is not potential for the assumed loading cases in the analysis, while the fatigue due to shear stresses is not verified in some sections near the openings of stands, therefore, the shear and fatigue capacities are essential for dynamic loading demands.

Using of new technique to reinforce concrete structures is needed to improve their strength against unexpected loads such as earthquake. The Computer Numerical Control (CNC) technique is one of the modern ways to configure the steel plate in any desired shape. RC shear wall is one of the important structural elements in the buildings. Reinforcing of concrete shear wall by embedded CNC steel plate instead of steel bars has been proposed in this study under cyclic loading. To implement the investigation of the new technique of reinforcement, a numerical simulation of the concrete shear wall specimen reinforced with ordinary steel bars under cyclic loading combined with vertical uniaxial load has been adopted from previous literatures. The numerical results have been verified with a selected experimental case results in term of hysteresis behaviour of the RC wall model. Then, the comparison in seismic behaviour of the ordinary and the proposed reinforcement technique of concrete shear wall model has been exhibited. Furthermore, three varied parameters have been inspected to explain the efficiency of the new technique. The parametric study includes reducing the thickness of steel CNC plate, cyclic loading path and steel yield strength. The results show significant enhancement of concrete wall strength by increasing the ultimate loading capacity when using embedded steel CNC plate technique by 173% with appropriate energy dissipation capacity. The new technique could be alternative process than traditional ways in the precast building construction industries to correspond the modern method of robot-based construction, as well to reduce the cost.