Thesis Doctorate Master- Post graduate -

Investigation of hydrodynamic demands of tsunamis in inundation zone

admin — Fri, 10 Apr 2009 19:31:46 +0000

This thesis analyzed the new parameter “hydrodynamic demand” repre-
senting the damage of tsunami waves on structures and coastlines,
maximum positive amplitudes and current velocities occurred during
tsunami inundation by using the numerical model TUNAMI-N2. Regular
shaped basins were used with two different bottom slopes in analyses in
order to understand the behaviour of tsunami wave and investigate the
change of important tsunami parameters along different slopes during
tsunami inundation. In application, different initial conditions were used for
wave profiles such as solitary wave, leading elevation single sinusoidal
wave and leading depression sinusoidal wave. Three different initial wave
amplitudes were used in order to test the change of distribution of the
hydrodynamic demand. The numerical results were compared and
discussed with each other and with the results of existing analytical and
experimental studies.

Ceren Özer
Investigation of hydrodynamic demands of tsunamis in inundation zone · 2007 · 146 sayfa.
Danışman: Doç.Dr. Ahmet Cevdet Yalçıner
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

Forced hydraulic jump on artificially roughened beds

admin — Fri, 10 Apr 2009 19:30:33 +0000

In the scope of the study, prismatic roughness elements with different longitudinal
spacing and arrangements have been tested in a rectangular flume in order to reveal
their effects on fundamental characteristics of a hydraulic jump. Two basic
roughness types with altering arrangements have been tested. Roughness elements of
the first type extends through the channel width against the flow with varying length
and pitch ratios for different arrangements. The second type is of staggered essence
and produced by piecing the roughness elements defined in the initial type into three
parts which are equal in length. The doublet formed from the pieces on the sides is
shifted to the consequent row to make two successive roughness rows encapsulate
the channel span completely. Staggered roughness type is formed with the repetition
of this arrangement along the flume. Independent of their type and arrangement, the
entirety of roughness elements are embedded in the channel bed in order to avoid
their protuberance into the flow, based on the presumption that the crests of the
roughness elements levelled with the channel inlet would be less exposed to caving
effects of flow than the protruding elements.

iv
In the study, influence of the proposed roughness elements on the fundamental
engineering concerns as the length, height (tail water depth) and energy dissipation
capacity of hydraulic jumps has been questioned in the light of empirical work and
related literature on forced and smooth hydraulic jumps.
At the final stage of the study, it was concluded that both strip and staggered
roughness have positive effects on the characteristics of hydraulic jump given above.
3-7% more energy dissipation was observed in jumps on rough beds compared to
classical hydraulic jumps. For tailwater dept reduction, whereas strip roughness
provided 5-13%, staggered roughness led to 7-15% tailwater depth reduction
compared to classical hydraulic jump. While strip roughness reduced jump length
around 40%, 35-55% reduction was observed with staggered roughness when
compared to classical hydraulic jump.

Çağdaş Şimşek
Forced hydraulic jump on artificially roughened beds · 2006 · 105 sayfa.
Danışman: Doç.Dr. Nuray Tokyay
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

A comparative assessment of an existing reinforced concrete building by using different seismic rehabilitation codes and procedures

admin — Fri, 10 Apr 2009 19:29:13 +0000

Lateral load carrying capacities of reinforced concrete structures which are designed
by considering only gravity loads or according to outdated earthquake codes can be
insufficient. The most important problem for these buildings is the limited ductility
of the frame elements. How to evaluate the performance of an existing structure and
to what level to strengthen it had been major concerns for structural engineers.

Recent earthquakes which occurred in the Marmara Region in the last decade have
increased the number of seismic assessment projects drastically. However, there
was no special guideline or code dealing with the assessment of existing buildings.
In order to have uniformity in assessment projects, a new chapter has been included
in the revised Turkish Earthquake Code (2006).

iv
In this study, the existing and retrofitted conditions of a reinforced concrete
building were assessed comparatively by employing linear and nonlinear
assessment procedures according to different seismic rehabilitation codes. The
study was carried out on a six storey reinforced concrete telephone exchange
building. Although there was no damage in the structure due to the recent
earthquakes that occurred in the Marmara Region, the building was assessed and
retrofitted in 2001 by using equivalent lateral load analysis results. The results of
linear and nonlinear assessment procedures performed in the scope of this thesis,
were also compared with the assessment results of this previous study.

In the nonlinear assessment procedures, pushover analysis results were used. In
addition to comparison of the assessment procedures, efficiency of a widely used
approximate pushover method was also investigated.

İsmail Öztürk
A comparative assessment of an existing reinforced concrete building by using different seismic rehabilitation codes and procedures · 2006 · 198 sayfa.
Danışman: Prof.Dr. Haluk Sucuoğlu
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

A numerical study on the dynamic behaviour of gravity and cantilever retaining walls with granular backfill

admin — Fri, 10 Apr 2009 19:27:50 +0000

Dynamic behaviour of gravity and cantilever retaining walls is investigated by
finite element method, incorporating the nonlinear elasto-plastic material
properties of soil and seperation of the wall and backfill. Two dimensional finite
element models are developed employing the finite element software ANSYS. The
wall is modelled to rest on a soil layer allowing translational and rotational
movements of the wall. Soil-wall systems are subjected to harmonic and real
earthquake motions with different magnitude and frequency characteristics at the
base. The maximum lateral force and its application point during dynamic loading
are determined for each case. It is observed that the frequency content of the base
motion has a significant influence on the dynamic lateral soil pressures and the
lateral forces considerably increase as the base motion frequency approaches the
fundamental frequency of the soil layer. The maximum lateral thrusts calculated
by finite element analyses are generally found to be greater than those suggested
by Mononobe-Okabe method and experimental findings. Nevertheless, the
locations of the application point obtained by finite element method are found to
be in good agreement with the results of experimental studies.

Ersan Yıldız
A numerical study on the dynamic behaviour of gravity and cantilever retaining walls with granular backfill · 2007 · 169 sayfa.
Danışman: Prof.Dr. Yener Özkan
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

Risk assessment of international construction projects using the analytic network process

admin — Fri, 10 Apr 2009 19:26:42 +0000

This thesis offers a comprehensive risk assessment methodology that provides a decision
support tool, directed for Turkish construction organizations, which can be utilized
through the bidding decisions for international construction projects. Within this context
the analytic network process technique is implemented to develop a risk assessment
model, which is used to derive the relative priorities of the risk factors associated with
international construction projects. The findings of the risk assessment model have
demonstrated that the most significant sources of risk are vagueness of contract
conditions about risk allocation, client, and immaturity of legal system in the host
country. Factors such as low % of advance payment, geographical distance, and bribery
were found to be relatively insignificant. An international construction project risk rating
software application is then developed. The application incorporates the derived
priorities from the risk assessment model to calculate a risk rating for a given
international construction project.
To increase the credibility of the results a risk rating adjustment methodology was
integrated into the application. Its purpose is to count for the potential influencing
factors that may increase the risk level of a given project. The influencing factors which
were considered are the company’s experience, contract type, level of the available
project data from the outset, and project delivery system.

The application is also structured to enhance the organizational learning practices. It
improves the process of the organizational memory formation with respect to post-
project risk data by developing a database of risk information of the rated projects for
future references. The reliability of the application was tested with post-projects risk
data and was found to be satisfactory.

Amanı Bu-Qammaz
Risk assessment of international construction projects using the analytic network process · 2007 · 206 sayfa.
Danışman: Prof.Dr. Mustafa Talat Bırgönül ; Prof. İrem Dikmen Toker
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

Tensile behavior of chemically bonded post-installed anchors in low strength reinforced concretes

admin — Fri, 10 Apr 2009 19:24:49 +0000

After the 1999 Kocaeli Earthquake, the use of chemically bonded post-installed
anchors has seen a great growth for retrofits in Turkey. Currently, chemically bonded
post-installed anchors are designed from related tables provided by adhesive
manufacturers and a set of equations based on laboratory pullout tests on normal or
high strength concretes. Unfortunately, concrete compressive strengths of existing
buildings, which need retrofit for earthquake resistance, ranges within 5 to 16 MPa.
The determination of tensile strength of chemically bonded anchors in low-strength
concretes is an obvious prerequisite for the design and reliability of retrofit projects.

Since chemically bonded anchors result in the failure of concrete, adhesive-concrete
interface or anchored material, the ultimate resistance of anchor can be predicted
through the sum of the contributions of concrete strength, properties of anchored
material (which is steel for this work), and anchorage depth. In this work, all three
factors and the predictions of current tables and equations related to anchorages are
examined throughout site tests.

Levent Maziligüney
Tensile behavior of chemically bonded post-installed anchors in low strength reinforced concretes · 2007 · 113 sayfa.
Danışman: Doç.Dr. İsmail Özgür Yaman ; Y.Doç.Dr. Erdem Canbay
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

Evaluation of minimum requirements for lap splice design

admin — Fri, 10 Apr 2009 19:23:38 +0000

Minimum requirements for lap splices in reinforced concrete members, stated in
building codes of TS-500 and ACI-318, have a certain factor of safety. These
standards have been prepared according to research results conducted previously and
they are being updated according to results of recent studies. However the reliability
of lap splices for minimum requirements needs to be investigated. For this purpose, 6
beam specimens were prepared according to minimum provisions of these standards.
The test results were investigated by analytical procedures and also a parametric
study was done to compare two standards. For smaller diameter bars both standards
give safe results. Results showed that the minimum clear cover given in TS500 is
insufficient for lap spliced bars greater than or equal to 26 mm diameter.

Doğu Bozalioğlu
Evaluation of minimum requirements for lap splice design · 2007 · 136 sayfa.
Danışman: Y.Doç. Erdem Canbay
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

Elastic layers bonded to reinforcing sheets are widely used in many

admin — Fri, 10 Apr 2009 19:21:50 +0000

Elastic layers bonded to reinforcing sheets are widely used in many
engineering applications, e.g., as elastic foundations to machinery, as seismic
isolators to structures, etc. Because of its practical importance, the behavior of
bonded elastic layers under some basic deformation modes (e.g., compression,
bending and shear modes) has attracted the attention of many researchers. However,
the analytical works available in literature involve, with the object of obtaining
design formulas, many simplifying assumptions. In this dissertation, a new
formulation is developed for the analysis of bonded elastic layers, which removes
most of the assumptions used in the earlier formulations. Since the displacement
boundary conditions are included in the formulation itself, there is no need to start
the formulation with some assumptions on stress and/or displacement distributions
or with some limitations on geometrical and/or material properties. For this reason,
the solutions derived from this formulation are valid not only for “thin” layers of
strictly/nearly incompressible materials but also for “thick” layers and/or
compressible materials.
The advanced solutions obtained within the framework of the new
formulation are used to study the behavior of bonded elastic layers under basic
deformation modes. The effects of three key parameters, shape factor, Poisson’s
ratio and reinforcement flexibility, on effective layer moduli, displacement/stress
distributions, and location/magnitude of maximum stresses are investigated. It is
shown that the stress assumptions of the “pressure” method are inconsistent with the
results obtained for thick layers and/or compressible materials and/or flexible
reinforcements, and that the assumption “plane sections remain plane” is not valid,
in general.

Seval Pınarbaşı
A new formulation for the analysis of bonded elastic layers · 2007 · 271 sayfa.
Danışman: Doç.Dr. Uğurhan Akyüz
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

Fragility based assessment of low-rise and mid-rise reinforced concrete frame buildings in Turkey using Düzce damage database

admin — Fri, 10 Apr 2009 19:20:06 +0000

In this study, the seismic fragility assessment of low-rise and mid-rise reinforced
concrete frame buildings which constitute approximately 75 % of the total building
stock in Turkey is investigated to quantify the earthquake risk. The inventory used
in this study is selected from Düzce damage database which was compiled after
the devastating 1999 earthquakes in the Marmara region. These buildings are not
designed according to the current code regulations and the supervision in the
construction phase is not adequate.

The building database is divided into sub-classes according to the height and
absence of infilled walls. Each building in the database is represented by an
equivalent single degree of freedom system with three structural parameters:
period, strength, and post-elastic stiffness ratio. The ground motion records are
selected from different parts of the world covering a wide range of characteristics.
The capacity of the structure is represented for each sub-class by the limit states.
Hence, a set of fragility curves for low- and mid-rise reinforced concrete structures
are developed by making use of the building characteristics in the database. The
generated fragility curve set is referred as “reference” since it forms the basis of a
parametric study. A parametric study is conducted to examine the influence of
post-elastic stiffness ratio, simulation and sampling techniques, sample size, limit
state definition and degrading behavior on the final fragility curves. Estimated
damage distribution after two consecutive major earthquakes is compared with the
actual field data in order to investigate the validity of the generated fragility
curves.

Keywords: .

Ahsen Özün
Fragility based assessment of low-rise and mid-rise reinforced concrete frame buildings in Turkey using Düzce damage database · 2007 · 107 sayfa.
Danışman: Y.Doç.Dr. Murat Altuğ Erberik
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.

Spatial optimization of hydrologic monitoring networks on rivers

admin — Fri, 10 Apr 2009 19:18:58 +0000

Efficient water resources planning and management must take into account multiple users,
criteria, and objectives. Due to this complexity of recent water management problems and
solutions, better analytical tools and methodologies are required. Accomplishment of this
requirement depends essentially on information gathered on natural and environmental
processes so the success of sustainable water resources management depends on
monitoring activities.
Many countries have developed extensive streamflow gauging networks. Such a
development has led to accumulation of significant amounts of data to eventually raise
questions whether they produce expected information, and whether monitoring should be
continued. These questions have led monitoring agencies to assess their current networks
for efficiency and cost-effectiveness.
The study is initiated in respect of above questions to examine various methodologies to
assess existing networks. The study also aims to develop some guidelines for consolidation
of a monitoring network. The investigation has resulted the use of multi criteria decision
making methodologies (MCDM). Consequently, the method of stream orders, a dynamic
programming approach and two MCDM methods are presented. The proposed study is
particularly focused on the assessment of the “performance” of existing networks. The
introduced methods are applied to Gediz River Basin and the results are evaluated with
respect to the ten operational and three non-operational stations. It is concluded that nonoperational
three stations are the ones to be removed from the network. Additionally the
advantages and disadvantages of the presented methods are discussed. Particular to the
network consolidation problem, reference point approach is found more useful.

Cem Polat Çetinkaya
Spatial optimization of hydrologic monitoring networks on rivers · 2007 · 140 sayfa.
Danışman: Prof. Dr. Nilgün Harmancıoğlu

Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.