الفهرس 
CHAPTER (1) “IntroductionOnly 14 pages are availabe for public view
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Abstract
Defects of structures bleed a lot of national income. Early detection and localization damage allow increased expectation of reliability; safety and reduction of the maintenance cost. A lot of studies appeared to evaluate the defected structures. Non destructive techniques are used to evaluate the defected structures. Advanced technique is a new approach to detect the damage of structural members. Structural monitoring systems based on measured structural vibration have been perceived to be able to assist structural inspection in the future. Sensitivity of measured modal properties to potential damage is very critical for their practical application. In this thesis, causes behind structure failures are reviewed. An extensive literature for structural damage detection such as material defects and fracture mechanism has been reviewed. An extra literature of advanced techniques of damage detection was reviewed. Modal tests and operation deflection shapes were proposed on a steel member including both intact and simulated damage states. It consists mainly of piezoelectric accelerometers, impact hammer, pulse analyzer with (modal analysis consultant software) and laptop. For three cases, the first free-free vibration, second boundry condition and third boundry condition with static load. Each case contains four beams. Damage is prepared by making artificial crack in flange at different locations (mid span, third span and quarter span Sensitivity of modal parameters to change of steel member condition was studied for (natural frequency, damping ratio, mode shape and operation deflection shape) through tables and figures analysis. The Finite Element Analysis (FEA) using (ANSYS) was conducted to study natural frequencies, mode shape, stresses and to correlate the results obtained using experiments. The steel beam is modeled by the three dimensional structural solid element (solid 45). This element is suitable for this analysis PDF created with pdfFactory Pro trial version www.pdffactory.com because the main objective is to determine mode shapes, natural frequencies and stresses of steel beam in case of intact beam and cracked beam. The Finite Element results from (ANSYS) are used to make comparisons between numerical solutions and experimental results through tables and analysis in terms of natural frequencies. For more explanation, the results of mode shape from experimental and numerical are given. Results show that, modal frequencies and mode shapes may be used to identify the structural damage with certain sensitivity and operation deflection shape. An artificially unmeasured excited force is a significant advantage in applying this forced vibration test as a greater range of procedure. These can be used more accurately for determining the modal parameters for practical structures when exciting force is unknown and complex to measure for ambient vibration test. The present results and concluded remarks can play an important role in developing an efficient condition maintenance plan for complex structures. Recommendations for practical applications and suggestions for further work in the field of structural damage detection are briefly discussed.