الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Dynamic properties of a hydraulic structure in terms of; frequency/time period,
mode shape and damping properties, play the major role in seismic design of hydraulic
structures or assessment of existing hydraulic structures. The seismic design depends
mainly on the value of ground acceleration which is a function in the natural period of
the structure. Therefore, the problem of choosing the value of ground acceleration in
design or assessment reflects on the cost needed for establishing or habitation of existing
hydraulic structure. Most of current codes do not involve the seismic design of this kind
of structures. Also, most of the existing hydraulic structures in Egypt, such as barrages
were built using bricks or plain concrete which has low resistance against tension stresses
induced in the piers due to seismic excitation. These structures are social, strategic and
sensitive for seismic loads. Besides that, the major benefits of hydraulic structures are
improving the situation of irrigation, improving river navigation as well as eliminating
the water shortage problems. Therefore, this current research aims to estimate the real
dynamic properties of a hydraulic structure as the first step to find its behavior under the
seismic loads. Also, investigating which parameters should be involved in and their
effect on results. To reach this aim, the Old Rayah Menoufi Barrage was selected as a
case study, that was simulated in three-dimensional Finite Element (FE) models using
ANSYS release 15 FE Software. The dynamic properties of the Old Rayah Menoufi
Barrage in terms of mode shapes, natural frequencies, and damping ratio were
investigated experimentally and numerically. The Old Rayah Menoufi Barrage is an old
existing hydraulic structure in Egypt that was permitted to be tested by the Construction
Research Institute (CRI) - National Water Research Center (NWRC) - Egypt. After the
estimation of the dynamic properties of the barrage, a time history analysis is mounted
for the most realistic FE model, investigating its dynamic behavior under an Earthquake
(EQ) time history record. For the numerical modal analysis, five various models are
established to simulate the studied barrage, that are varied in the base condition (stiffness
of the soil). However, the Experimental Modal Analysis (EMA) gives the realistic
behavior of the tested structure, it requires some control to get accurate results. This control is represented in several factors; the method of excitation, the sampling rate of
the recorded data, and the locations grid of the measurement sensors. Therefore, a prefinite
element model is required to adjust these factors. This model is called Initial Model
(IM). In this model, all structural elements of the barrage were simulated using solid 3D
elements with its real corresponding material properties. Water through the vents and the
lock chamber of the barrage was modelled using Housners` simulation [1]. The fixed
base condition of the barrage was adopted in this model, neglecting the Soil Structure
Interaction (SSI). Great significant differences were observed between them, so four
Updated Models (UM1, 2, 3, and 4) were mounted to decrease this variation and achieve
more realistic results close to the Experimental Work (EW). In the updated models, the
SSI was considered through this model, changing the base condition from fixed to soil
subgrade reactions. The vertical stiffness of the subgrade reactions was chosen as an
average value of the Bowles` subgrade reactions [2], according to the soil properties
under the base of the used barrage. Since, the horizontal subgrade reactions were
considered as a percentage of the vertical reaction (0%, 10%, 30% and 50% for UM1,
UM2, UM3 and UM4, respectively). The updated models are compared with the EW to
obtain the most realistic results. These comparisons showed that UM3 with the ratio of
30% of the vertical subgrade reaction is the most matching model that is close to the EW.