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İnşaat mühendisliği yapı güvenliği ekonomik ve işlevsel yapı imalat
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Multi-hazard assessment stochastic analysis tsunami hazard curve sea level rise
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Tsunami, hazard assessment, nuclear power plant
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Stochastic analysis Monte Carlo simulation tsunami simulation flood potential combined hazard assess
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Air resistance, Energy dissipation, Flip bucket, Ski-jump jet
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Tsunamijenik depremler, monte carlo simulasyonu, sosyal risk analizi
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Misinterpretation of rupture parameters, displacement, historical earthquakes, overestimation of tsu
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A free-fall water jet released from a spillway may cause significant scour on the downstream river reaches due to high dynamic pressures. Energy dissipators are generally used at the downstream of a spillway to disperse the energy of the water jet. In case of low air concentration, the jet may hit the river bed with high dynamic pressure heads that can cause significant scour adjacent to the dam body. The scour can cause significant stability problems on the dam body. To prevent the phenomenon, water cushion can be a practical tool to reduce the jet impact at the impingement area. In this study, the effectiveness of the water cushion is inspected by measuring the dynamic pressure variations against different discharges and varying water cushion levels. The results of the experimental study show that dynamic pressure reduction is reversely proportional to the water cushion level until a certain discharge. Then, water cushion level changes become meaningless, especially for small discharges.
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Water jet, Dynamic pressure, Impact assessment, Water cushion, Scour
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Scour always be a significant problem for the stability and safety of a dam. Water jet issued from flip bucket of a dam creates an air-water mixture and finally plunges at the downstream of a dam. Depending on the discharge, total head, thickness of the water body, aeration conditions and geometrical features of the flip bucket, the jet is dispersed in air. It is obvious that air concentration is inversely proportional with the dynamic pressures at impingement area of the water jet coming from the flip bucket of spillway of a dam. Impact of the ski jump jet at the impingement point may be reduced depending on the air concentration of the jet. In this study, experimental and numerical assessments are performed to analyze the distribution of the air into the ski jump jet depending on the dynamic pressures at the impingement point. The impact of the ski jump jet is analyzed and air percentages are defined into the jet according to dynamic pressure measurements using pressure transmitters at the impingement area. By doing so, aeration characteristics and impact values of water jets are revealed to generate reliable scour estimates for future researchers.
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Air concentration, ski jump jets, dynamic pressure distribution, jet dispersion, numerical solution
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Climate change impacts on social and economic assets and activities are expected to be devastating. What is as important as the analysis of climate change triggered events is the analysis of a combination of climate change related events and other natural hazards not related to climate change. Given this observation, the purpose of this study is to present a coastal risk analysis for potential earthquake triggered tsunamis (ETTs) coupled with the sea level rise (SLR) in the Eastern Mediterranean Sea. For this purpose, extensive stochastic analysis of ETTs, which are not related to climate change, are conducted considering the effects of climate change related SLR projections for this century. For the combined analysis, economic and social risks are evaluated for two regions in the Eastern Mediterranean Coastline, namely the Fethiye City Center at the Turkish Coastline and the Cairo Agricultural Area near Egypt. It is observed that ignoring SLR will hinder realistic evaluation of ETT risks in the region. Moreover, spatial evaluations of economic and social risks are necessary since topography and proximity to the earthquake zones affect inundation levels due to ETTs in the presence of SLR.
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Natural hazard, climate change, sea level rise, earthquake triggered tsunami, social and economic ri
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In this study, we present a novel methodology that may be used to analyze tsunami risk along coastal regions. The application of the proposed methodology is demonstrated for the Eastern Mediterranean coast. Economic, social and environmental dimensions of risk are calculated and aggregated to obtain the overall risk maps for a number of elements at risk (EaR) that are identified from seven countries located along the Eastern Mediterranean coastline. Historical earthquakes that are recorded in the region during the period 1900–2013 are used as data, and probabilistic tsunami modeling is carried out using Monte Carlo analysis. Based on historical data, randomly generated earthquakes are simulated, and wave propagation analysis is performed using NAMI-DANCE software. Inundation depth–damage analysis and exceedance probabilities of tsunami inundations are used to evaluate social and economic risks while the environmental risk is calculated using a binary approach. The overall risk map is constructed in the geographic information system environment. Cairo Agricultural Area in Egypt and Fethiye City in Turkey are identified as high-risk EaR in the Eastern Mediterranean coastline. The new risk assessment methodology may be utilized in coastal regions of the world, and the results obtained for the Eastern Mediterranean may be effectively used in developing preventive measures and disaster management strategies for tsunamis that may develop the region.
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Geographic information systems (GIS), Monte Carlo analysis, Risk assessment, Tsunami modeling
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Java (Sunda) trench lying along the eastern and southern coasts of Indonesia is one of the world‘s most active seismic zone. Java (Sunda) trench experienced devastating earthquakes and tsunamis throughout history. Despite the fact that about 14 years have passed since the 2004 Indian Ocean earthquake and tsunami, the seismic activity in this region is still intense. Thus, reliable estimation of the associated hazard of a possible large earthquake that can generate tsunami is vital for designing early warning systems, site selection of future critical infrastructures (CIs) and planning necessary mitigation measures for existing CIs and critical regions (CRs). Therefore, Scenario-based Tsunami Hazard Assessment (STHA) is performed for this region in this study. Historical earthquake data is compiled using ISC-GEM Global Instrumental Earthquake Catalogue for the region. Monte Carlo (MC) simulation method is used to generate random earthquake source parameters (i.e. magnitude, focal depth) along Java (Sunda) trench. The worst-case scenario among MC runs is selected and simulated using NAMI-DANCE tsunami simulation software. Critical Regions (CRs) and Critical Infrastructures (CIs) are identified and spatial distribution of the inundation levels along the eastern and southern coastline of Sumatra and Java Islands, focusing on these CRs and CIs is determined. It is observed that some of the CRs and CIs are vulnerable to potential high-risk tsunamis.
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Scenario-based tsunami hazard assessment, Monte Carlo, NAMI-DANCE, Critical regions, Critical Infras
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Scour downstream of a dam can be a significant threat for stability and safety of a dam. Therefore, estimation of energy dissipation for ski jump jet in surrounding air becomes one of the most significant design criteria for a dam. The main goal of this study is the estimation of head loss in ski jump jets due to air entrainment in prototype scale. In order to accomplish this purpose, estimation of the energy reduction amount for ski jump jets were conducted using empirical methods to calculate the trajectory lengths with and without air entrainment. Estimation of energy reduction method is based on an experimental study conducted to analyze the impact assessment of water jets from flip buckets. Head loss calculations are performed for different prototype discharges. It is concluded that energy reduction due to air entrainment for ski jump jets becomes stable after a certain discharge amounts.
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Air Entrainment, Energy Reduction, Flip Bucket, Head Loss Estimation, Ski jump
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Cavitation can be a significant thread for hydraulic structures. This phenomenon occurs when vapor pressure drops below static pressure. Occurrence of the cavitation can cause cavitation erosion that can damage the parts of the pipes, turbines or pumps. In this study, pipeline system which will be constructed in a part of hydraulic works is investigated numerically using commercially available ANSYS Fluent software in terms of cavitation problem. By varying inlet boundary condition, the maximum velocity that cause cavitation not to occur and the velocity that cause cavitation just to occur is determined. Results of the numerical simulations are visualized. In addition, minimum static pressure and maximum velocity of the pipeline system are determined and compared with the vapor pressure. It is shown that for the given boundary conditions, cavitation does not take place. On the other hand, if the inlet velocity is increased to 5.7 m/s or further, cavitation can be observed depending on flow and structural conditions.
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Cavitation, Static pressure, Vapor pressure, Numerical Model, ANYSIS-FLUENT, GAMBIT
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Water jet issued from flip bucket at the end of the spillway of a dam can be a threat for the stability and safety of the dam body due to subsequent scour at the impingement point. However, a strong jet from the flip bucket interacts with the surrounding air and develops into an aerated turbulent jet while the jet impact and scouring effect is reduced significantly. Aeration of the jet, at the same time, cause head losses along the trajectory. An experimental study is conducted to measure the trajectory lengths and investigate the effect of water depth in the river on the dynamic pressures acted on the river bed. The trajectory lengths with and without air entrainment are calculated using empirical equations and compared with the measurements. Head losses due to air entrainment are determined using the difference of the trajectory lengths with and without aeration, based on the projectile motion theory. Numerical simulation of the flow over the spillway, along the flip bucket and the jet trajectory is made and the results are compared with the experimental data. It is observed that trajectory lengths obtained from experiments, numerical simulation and empirical formulas are comparable with negligible differences. This allows us to combine alternate approaches to determine the trajectory lengths with and without air entrainment and estimate the head losses accordingly.
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Water Jet, Flip Bucket, Impact Assessment, Trajectory Length, Jet Dispersion, Numerical Method
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Hazard evaluation, tsunami, stochastic analysis
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Trajectory length determination is one of the significant issue for downstream part of a dam. Jet thickness, relative fall height, bucket shape and air resistance may cause drastic energy loss for the trajectory. If the location where the ski-jump jet plunge into the river bed is not correctly determined, excessive scour at the river bed may observed. Prototype trajectory lengths with air resistance can be determined using both empirical and numerical solutions. Bottom outlet trajectory lengths of Inoren Regulator and HEPP are calculated with empirical equations compared with numerical solutions applied by using Flow-3D software. The results can shed light on the designers to determine the plunge location of trajectory lengths with air entrainment for accurately determine design criteria for the plunge pool at the downstream part of the dam.
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Water Jet, Flip Bucket, Trajectory Length, Energy Loss, Air Resistance, Scour, Flow-3D
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Eastern Mediterranean, which contains the coasts of Greece, Turkey, Syria, Lebanon, Israel, Egypt and Cyprus experienced numerous earthquakes and also tsunamis throughout the history mainly due to the Hellenic and Cyprus archs. Many lives are lost and high economic damages are experienced. For example, 1822 and 1872 earthquakes and tsunamis that took place in Levantine basin revealed that 20 thousand people lost their lives in Hatay province, Turkey. The earthquake of magnitude 6.7 and the tsunami that occurred at Gokova in July 20, 2017 indicate that the seismic activity in this region is still intense. Therefore, reliable risk assessment of earthquakes that can generate tsunamis is vital for the positioning of early warning systems, site selection of future critical infrastructures (CIs) and planning necessary mitigation measures for existing Elements at Risk (EaR). In this study, Probabilistic Tsunami Risk Assessment (PTRA) is conducted for Eastern Mediterranean region. EU funded TRANSFER Project’s Earthquake Catalogue is used to gather 523 historical earthquakes in the region. Earthquake source parameters for the historical earthquakes are obtained from the same Catalogue and Monte Carlo Simulations (MCSs) are used to carry out PTRA. Sufficient number of MCSs required to obtain realistic results are identified based on the evaluation of change in the total economic risk. A total of 91 EaR is identified at the coasts of Eastern Mediterranean and total economic risk for these EaR are calculated for varying number of MCSs. NAMI-DANCE software is used to model tsunamis and country specific depth-damage curves are used to estimate economic risks. It is observed that around 1000 MCSs is sufficient to obtain representative economic risk for the study area.
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Monte Carlo simulation, tsunami hazard, risk assessment
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Various fluid structure interaction (FSI) models have been proposed in literature. FSI systems have been solved by simulating the fluid and structure either with solely mesh free or mesh-based methods. However, there are few researches that couple mesh free and mesh-based methods to interact fluid and structure. In the present study, a fluid structure interaction model is proposed in which fluid is simulated with Smoothed Particle Hydrodynamics (SPH) as a mesh free method and structure is simulated with a well-known mesh-based method (FEM). A well-known contact mechanic model is modified to simulate the interaction. In the model, water particles invading the solid domain are taken out the solid structure by using the modified contact mechanics algorithm. The validations show that the proposed FSI model is promising.
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fluid-structure-interaction, FSI, smoothed particle hydrodynamics, SPH, contact mecha
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Murat nehri üzerinde yapılmakta olan Yukarı Kaleköy Barajı ve HES’in dolusavak yapısına ait hidrolik model çalışmaları ODTÜ İnşaat Mühendisliği Bölümü Hidromekanik Laboratuvarında yapılmıştır. Dolusavak yapısı girişinde ve üzerindeki akım şartlarının incelenmesi amacı ile yapılmış olan bu model çalışması iki aşamada gerçekleştirilmiştir. 1/70 ölçekli imal edilen orijinal model, ortak ayırma duvarına sahip fakat boykesitleri farklılık gösteren bitişik iki dolusavak deşarj kanalından oluşmaktadır. Bu model üzerinde gerekli olan çalışmalar tamamlandıktan sonra, deşarj kanalları arasındaki ayırma duvarı kaldırılmış ve kanalların boykesitleride aynı kotlara alınarak yapı tek deşarj kanallı olarak revize edilmiştir. Her iki durumda da model üzerinde, verilen akım şartlarında yapı üzerindeki su derinlikleri ve basınç değerleri ölçülmüş ve mevcut havalandırıcıların yeterli olmadığı tespit edilmiştir. Yapı üzerindeki akımın yeterli derecede havalandırılabilmesi ve kavitasyon riskinin oluşmaması için gerekli olan havalandırıcıların boyutları belirlenmiştir. Bu çalışmada model üzerinde yapılan deneyler, elde edilen ölçümler, bunlarla ilgili veriler, eski ve yeni havalandırıcıların akım şartları üzerindeki etkileri sunulmuştur.
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Dolusavak modelleri, Dolusavak havalandırıcıları, Hidrolik deneyler, Kavitasyon
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Mediterranean experienced numerous earthquakes and some of them triggered tsunamis throughout the history. Historical records, locations of fault zones and volcanoes indicate that there are some tsunamigenic sources in the Mediterranean Sea. Thus, tsunami hazard assessment of the region is important for designing early warning systems, site selection of future critical infrastructures (CIs) and planning necessary mitigation measures for existing CIs and settlement areas. In this study, a probabilistic analysis of past tsunamis is conducted. Then, previously recorded tsunamis originated at a critical source zone in the Mediterranean Sea are simulated using NAMI-DANCE software to estimate inundation depths at Mersin coastline, especially where CIs such as ports, industrial zones, and waste water treatment plants are located. Simulated run-up results are assessed and probabilistic distribution of the inundation levels are analyzed for gauge points located at CIs. It can be seen that some of the existing CIs are vulnerable to probable future tsunamis.
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Tsunami, probabilistic tsunami analysis, critical infrastructures, NAMI-DANCE
Özet Metin
A jet issued from flip bucket of spillway of a dam interacts with the surrounding air and develops into an aerated turbulent jet. Depending on the relative jet thickness, the fall height and the level of turbulence, the jet may be dispersed in air forming an aerated water body which will eventually plunge into the river surface at sufficiently far downstream of the flip bucket. If not aerated, the jet may have a larger impact on the river bed causing severe scour damage. Water cushion and dispersion of jet by aeration are the practical tools to reduce the jet impact. An experimental study is conducted to analyze the contribution of water cushion to damp the dynamic pressures on the bed. The jet impact is analyzed using geometric elements of the jet trajectory in an effort to characterize the jet impact conditions in terms of relevant dimensionless parameters. It is observed that aeration of the jet is more effective in minimizing the impact when compared to the contribution of water cushion depth.
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Water Jet Flip Bucket Impact Assessment Water Cushion Air Entrainment
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Beyhan 1 Barajının dört ünitedenoluşan su alma yapısının hidrolik model testleri Orta Doğu Teknik Üniversitesi İnşaat Mühendisliği Bölümü Hidromekanik Laboratuvarında yapılmıştır. Farklı işletme durumlarında akım koşulları, girdapların gelişme ve sönümlenmesinin incelenmesinin yanısıra, hava çeken girdapların önlenmesi için girdap önleyici araçlar belirlenmiştir. Su alma yapısıünitelerini birbirinden ayıran dikey duvarlarla birlikte mütemadi sundurma duvarının kullanılmasınınen iyi sonucu verdiği tespit edilmiştir.
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Hidrolik Model Girdap oluşumu Girdap Önleyici Araçlar
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Alparslan II baraj ve Hidroelektrik santraline ait basınçlı iletim tüneli kapaklarının hidrolik model testleri Orta Doğu Teknik Üniversitesi İnşaat Mühendisliği Bölümü Hidromekanik laboratuvarında gerçekleştirilmiştir. Deneysel çalışma 1/26.5 ölçekli modelde Froude sayısı benzerliğine göre yapılmıştır. Model kapak üzerinde çeşitli debilerde ve kapak açıklıklarında aşağı yönlü hidrodinamik çekme kuvvetleri ölçülmüştür. Kapağın kapanması esnasındaki hava ihtiyacını ve türbin kapanırken kapak yuvalarındaki su yüksekliğini tahmin etmek için tek boyutlu hesaplama modeline dayalı bir bilgisayar çözümü yapılmış, çeşitli başlangıç debilerinde cebri borudaki maksimum hava akımı hesaplanmıştır.
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Tsunamis are rarely experienced events that have enormous potential to cause large economic destruction on the critical infrastructures and facilities, social devastation due to mass casualty, and environmental adverse effects like erosion, accumulation and inundation. Especially for the past two decades, nations have encountered devastating tsunami events. The aim of this study is to investigate risks along the Mediterranean coastline due to probable tsunamis based on simulations using reliable historical data. In order to do this, 50 Critical Regions, CRs, (i.e. city centers, agricultural areas and summer villages) and 43 Critical Infrastructures, CIs, (i.e. airports, ports & marinas and industrial structures) are determined to perform people-centered risk assessment along Eastern Mediterranean region covering 7 countries. These countries include Turkey, Syria, Lebanon, Israel, Egypt, Cyprus, and Libya. Bathymetry of the region is given in Figure 1. In this study, NAMI-DANCE is used to carry out tsunami simulations. Source of a sample tsunami simulation and maximum wave propagation in the study area for this sample tsunami are given in Figures 2 and 3, respectively.Richter magnitude,, focal depth, time of occurrence in a day and season are considered as the independent parameters of the earthquake. Historical earthquakes are used to generate reliable probability distributions for these parameters. Monte Carlo (MC) Simulations are carried out to evaluate overall risks at the coastline. Inundation level, population density, number of passenger or employee, literacy rate, annually income level and existence of human are used in risk estimations. Within each MC simulation and for each grid in the study area, people-centered tsunami risk for each of the following elements at risk is calculated: i. City centers ii. Agricultural areas iii. Summer villages iv. Ports and marinas v. Airports vi. Industrial structures Risk levels at each grid along the shoreline are calculated based on the factors given above, grouped into low, medium and high risk, and used in generating the risk map. The risk map will be useful in prioritizing areas that require development of tsunami mitigation measures
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Drainage gates, Saemangeum tidal dyke, Hydraulic experiments, 3D Numerical analysis