Ali BOZER

Makale/Derleme | 2013 | STRUCTURAL CONTROL & HEALTH MONITORING

The optimization of tuned mass damper (TMD) involves the attachment of a damper to a TMD unit. Although thissupplementary damping renders TMD to be operational under broad bandwidth inputs (i.e., wind excitation), italso considerably decreases the efficiency. In this paper, an alternative approach is suggested to eliminate therequirement for supplementary damping, hence to utilize TMD in full efficiency. For this purpose, combinedstructure/undamped TMD system is equipped with an active controller to track the response of an oscillatorwith natural frequency set to the operating frequency of the TMD unit. In this case, a proposed cont . . .roller doesnot aim returning a system to its zero state; instead, it supports the TMD unit to suppress vibration effectively.This tracking type controller is formulized by both linear quadratic regulator, andH1control schemes, andcontrol performances of each system are evaluated through numerical simulations. Copyright © 2011John Wiley & Sons, Ltd Daha fazlası Daha az

Şaban Suat ÖZSARIYILDIZ | Ali BOZER

Makale/Derleme | 2015 | STRUCTURAL DESIGN OF TALL AND SPECIAL BUILDINGS

In this paper, optimum design of tuned mass damper for seismically excited structures is discussed. In thedesign process, a benchmark multi-degree of freedom system is considered, and the performance measureof the optimization criterion is selected as the H2and H1norms of the transfer function of the combinedtuned mass damper and building system. Differential evolution algorithm is then utilized to minimize theseobjective functions. The objective function choice on performance and the effectiveness of differential evo-lution optimization algorithm in comparison with other algorithms in the literature are investigated throughnumerica . . .l simulations. Copyright © 2014 John Wiley & Sons, Ltd Daha fazlası Daha az

Ali BOZER

Makale/Derleme | 2017 | PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-STRUCTURES AND BUILDINGS

Non-ductile, concentrically braced frames are a common lateral force-resisting system used in low-to-moderate seismic regions in the USA. However, their dynamic responses to earthquake ground motions have not been well examined. Structural engineers usually design them conservatively as brittle structures with a small response-modification factor, while building codes restrict their use to low-rise buildings. In this paper, seismic responses of two typical non-ductile concentrically braced frames, one of three storeys and one of nine storeys, were predicted through a neural network model. Twelve input parameters, covering non-linear . . . features from structural components and the uncertain nature of earthquake ground motions, were used in the modelling. Numerical results extracted from thousands of non-linear time-history analyses under one set of moderate ground motions were used to develop the model. Sensitivity analyses were conducted to evaluate the impacts of input parameters on the peak inter-storey drift ratio, designed as an output parameter in the model. The results are shown to be promising considering the uncertainties in both ground motions and the characteristics of structures Daha fazlası Daha az

Ali Bozer

Makale/Derleme | 2017 | PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-STRUCTURES AND BUILDINGS

The non-linear numerical analysis of reinforced-concrete structures presents several difficulties due to the complicated behaviour of reinforced concrete under cyclic lateral loading. For practical use, design guidelines provide simplified non-linear models which are implemented in many structural analysis programs. However, restrictions and assumptions on which the models are based may influence the seismic response of existing structures. The primary aim of the work reported in this paper was to identify possible differences in structural response due to selected non-linear modelling parameters. Based on these findings, the aim wa . . .s then to provide guidance for practical computer models capable of representing a realistic non-linear seismic response. A set of numerical models was constructed and then a force–deformation relationship for each model was compared with experimental results. Sensitivity of response due to changes in each member's modelled plasticity and hysteresis was further investigated on a ten-storey reinforced-concrete building under five different seismic inputs. The analyses confirmed that storey displacements and degree of plastic deformation were influenced by modelling preferences. A fibre model was found to be more reliable in reflecting non-linear behaviour Daha fazlası Daha az

Ali BOZER | Şaban Suat ÖZSARIYILDIZ

Makale/Derleme | 2018 | STRUCTURAL CONTROL & HEALTH MONITORING

In optimization of multiple tuned mass dampers (MTMDs), certain restric-tions or preconditions such as uniform distribution of stiffness, mass, or fre-quency spacing had been applied for simplification, but in turn, solution ofindividual stiffness and damping parameters are not the true optima. Themain purpose of this paper is to obtain the true optima of individual stiffnessand damping parameters of MTMD system. In the proposed method, param-eters of TMD units are treated as free search optimization variables, and anefficient optimization algorithm, namely, artificial bee colony algorithm hasbeen utilized in obtaining optimum param . . .eters of MTMDs. Performance pro-posed method with respect to uncontrolled structure is verified throughnumerical analyses and compared with other reported methods. Comparisonsshow a superior performance of proposed approach. The basic properties ofoptimum design, the effectiveness, and robustness with respect to numberof dampers are also discussed Daha fazlası Daha az

Alper AYDEMİR

Makale/Derleme | 2017 | Civil Engineering and Environmental Systems

Dam failures are catastrophic accidents resulting in property damage and loss of life. Risk prioritisation systems should be used in accordance with dam safety regulations to prevent these disasters. The purpose of this paper is to develop a risk assessment software which can be used by the decision makers for ranking of dams. Risk assessment was conducted on three embankment dams from Turkey to obtain information about the dam performance based on piping, earthquake, normal stability and flood failure modes. Parameters are incorporated into the programme to develop a new model that could predict variables such as breach width, dam . . .failure time, side slope and peak breach discharge. The proposed tool gives flexibility to choose dam elements for describing the primary features of the evaluated dam; so users can make hazard categorisation of dams according to their risk level which is based on unique project conditions Daha fazlası Daha az

Alper AYDEMİR

Makale/Derleme | 2017 | Harran Üniversitesi Mühendislik Dergisi

Barajların elektrik üretimi ve sulama gibi alanlarda elde edilecek faydaları ile ülke ekonomilerine katkılarının yanı sıra çevre düzenlemesi, ulaşım ve taşkın koruma gibi alanlarda da faydaları bulunmaktadır. Ancak oluşabilecek aksaklıklar baraj yapılarının yükseklikleri ve aktif depolama hacimlerinin büyüklüğüne göre farklı seviyelerde tehlikeler meydana getirmektedir. Özellikle baraj alanlarına yakın yerleşim bölgeleri için barajlarda oluşabilecek yıkılmanın önceden minimum hata ile tahmin edilebilmesi hayati önem taşımaktadır. Bu çalışma baraj yıkılma modellerinde kullanılan debi tahmin yöntemlerinin temel amaçları, hesap yönteml . . .eri ve uygulama alanları ile elde dilecek sonuçların karşılaştırılmasını içermektedir. Literatürde bulunan ve bu araştırmada incelenen yöntemler tarihi baraj yıkılma verilerine istatistiksel regresyonlar uygulanarak elde edildiği için bazı durumlarda yetersiz kalmaktadır; özellikle bu verilerin elde edildiği baraj türlerinin (baraj yüksekliklerinin) tüm barajları içermemesi sebebiyle önerilen regresyon denklemlerinin yüksek belirsizlikleri olduğu görülmektedir. Dams have benefits such as electricity generation and irrigation for national economy as well as recreation, transportation and flood prevention could be given as other benefits. However, possible failures could cause different level hazards according to dam height and active storage volumes of dams. Especially for people living in inundation zones of dams, it is essential to predict dam breach simulations with lowest uncertainty. In this study, dam breach peak discharge prediction methods are compared based on their principles, applications and formulations. Since the methods obtained from the literature were derived from regression analysis of historical dam failures, these methods are insufficient in some situations, especially the historical data used in these studies does not include all dam failures or some types of dam data are missing. Hence, it is obvious that regression equations include high uncertainty Daha fazlası Daha az

Alper AYDEMİR

Bildiri | 2014 | Uluslararası Katılımlı IV. UlusalBaraj GüvenliğiSempozyumu Bildiri Kitabı , pp.489 - 496

Dünya nüfusundaki hızlı artış ile doğru orantılı olarak insanların suya olan ihtiyaçları da artmaktadır. İnşaat mühendisliği alanındaki gelişmeler daha yüksek barajların yapılmasına ve baraj göllerinde tutulan suyun geçmiş yıllara göre çok daha büyük miktarlara ulaşmasına imkân sağlamaktadır. Barajların sulama, elektrik enerjisi üretimi, taşkından koruma ve içme suyu depolama gibi çok çeşitli amaçları vardır. Ancak inşaat veya işletme aşamalarında meydana gelebilecek aksaklıklar baraj yıkılmalarına sebep olmaktadır. Baraj yıkılmalarının çevresel ve ekonomik etkilerinin yanında, yıkılma sonucunda çok ciddi can kayıpları da meydana ge . . .lmektedir. Oluşabilecek kayıpları azaltmanın en etkili yolu baraj yıkılma süresinin hesaplanması ve erken uyarı sistemlerinin kullanılmasıdır. Baraj güvenliği için risk, barajda herhangi bir aksaklığın meydana gelme olasılığının sayısal olarak ifade edilmesidir. Özellikle ekonomik yetersizlikler sebebiyle tüm barajlara eşit kaynak aktarılması ve yüksek maliyet gerektirecek incelemeler gerçekleştirilmesi zordur. Bu sebeple baraj risk değerlendirmeleri yapılarak öncelikle yüksek risk değerine sahip ve yıkılma durumunda çevresinde yaşayan insanları tehdit etme olasılığı en yüksek barajlar belirlenerek bu barajlar üzerinde detaylı araştırmalar yapılmalıdır. Bu çalışmanın amacı Türkiye’den seçilen bir baraj üzerinde yıkılma parametrelerini belirleyerek, bu barajın risk değerlendirmesini yapmaktır. Risk analizi için Utah Üniversitesi tarafından Federal Emergency Management Agency’nin (FEMA) kullanımı için hazırlanmış olan EXCEL tabanlı risk analizi yazılımı (FEMA Risk Tool) kullanılmıştır. İncelenen barajın risk analizi sonuçlarına göre; borulanma durumu için risk değerinin yüksek olduğu görülmüş ve alınabilecek önlemler açıklanmıştır. Geliştirilen yazılım, barajların hızlı ve etkili bir şekilde sıralanmasına olanak sağladığı için çok sayıdaki baraj üzerinde kısa sürede uygulanabilmektedir. People's water needs are increasing in direct proportion along with the rapid increase in world population. Advances in civil engineering are intended to allow building higher dams and to store water in dam reservoirs much more than past years. Dams have different purposes such as irrigation, hydropower, flood control and drinking water storage. Errors during construction and operation periods of dams could cause dam failures. The effects of dam failures could be environmental and economic as well as failures could cause loss of life. Calculating dam failure time and using early warning systems could prevent loss of life and property damages. Risk in dam safety means, numerical probability of misoperation of any dam part. Because of economical deficiencies, it is hard to pay equal attention or to make high cost detailed examinations for all dams. For this reason risk assessment must be performed for all dams and detailed research could be made for dams that have high risk value or dams that could threat population living near dam. The aim of this study is to clarify dam failure modes and to make risk analysis of a dam from Turkey. For this purpose, an Excel based risk analysis tool was used. This tool was created by UTAH State University for the use of Federal Emergency Management Agency (FEMA). Results of risk analysis showed that piping failure risk value is high for embankment dams and recommended actions for this failure mode is explained. This software helps to sort dams effectively and fast. So it can be applied many dams in a short time Daha fazlası Daha az

Alper AYDEMİR

Bildiri | 2012 | Uluslararası Katılımlı III. Baraj Güvenliği Sempozyumu Bildiri Kitabı , pp.247 - 258

Günümüzde küresel ısınma nedeniyle yenilenebilir enerji kaynaklarının önemi her geçen gün artmaktadır. Ülke ekonomisine önemli katkısı bulunan su kaynaklarının verimli kullanılması yeni istihdam alanları yaratabileceği gibi mevcut olanakların geliştirilmesinde de önemli rol oynamaktadır. Barajların, tarım arazilerinin sulanması, elektrik enerjisinin üretimi, taşkın kontrolü, balıkçılık, iç sularda ulaşım gibi pek çok faydaları bulunmaktadır. Barajların bu önemli özelliklerinin yanında baraj yıkılması sonucunda çok ciddi can kayıplarına ve maddi hasarlara yol açabilecekleri unutulmamalıdır.Baraj güvenliği açısından oluşabilecek tehli . . .kelere karşı risk analizleri bütün barajlar için yapılmalı ve baraj durumları sürekli olarak izlenmelidir.Bu çalışmanın amacı risk analizi yazılımı geliştirerek, baraj güvenliğinin Türkiye’deki durumunu belirlemektir. Bu kapsamda, öncelikle farklı ülkelerde baraj güvenliği konusunda yapılan çalışmalar araştırılmış ve kullanılan çeşitli yönetmelikler incelenmiştir. Çeşitli baraj türleri için tehlike oluşturabilecek parametreler belirlenmiş, baraja yakın bölgelerde yaşayan ve olası bir yıkılma durumunda etkilenebilecek insan sayıları, bölge haritaları ve nüfus bilgileri kullanılarak belirlenmeye çalışılmıştır.Risk analizi için Utah Üniversitesi tarafından Federal Emergency Management Agency’nin (Fema) kullanımı için hazırlanmış olan EXCEL tabanlı risk analizi yazılımı (FEMA Risk Tool) kullanılmıştır. Yazılım baraj yüksekliği, baraj gövde türü, dolu savak kapasitesi, ortalama yıllık yağış miktarı, ana kanal uzunluğu, ortalama havza yüksekliği gibi temel baraj karakteristiklerini kullanmaktadır. Herbir baraj türü için risk analizinde kritik öneme sahip değişkenlere göre analiz yapılmıştır. Örneğin toprak dolgu barajlar için yıkılma modları, taşkın, deprem, normal stabilite ve sızıntı durumlarıdır.Yazılıma gedik genişliği hesabı, yıkılma süresinin belirlenmesi, çıkan en büyük debi miktarının bulunması için kullanılan ampirik yöntemler ve gedik şev eğiminin bulunması için kullanılan çeşitli metotlar da eklenmiştir. Geliştirilen bu yazılım kullanılarak Türkiye’deki bir baraj üzerinde risk analizliyapılmıştır. Yapılan risk analizleri sonucunda oluşabilecek tehlikeler 3 farklı kategoride toplanmıştır. Bunlar yüksek tehlike, önemli tehlike ve düşük tehlike durumlarıdır. Yapılan çalışmanın sonucu olarak önemli risk parametreleri ve oluşturabilecekleri tehlike durumlarına göre grafiksel sonuçlar elde edilmişve eklenen yeni metotlar için de grafikler hazırlanarak sonuçlar yorumlanmıştır. Nowadays importance of renewable energy sources increased due to global warming. Effective use of water resources can play important role on economics; this can create new employment areas and helps improvement of existing possibilities. Dams have benefitable functions such as irrigation, hydropower, flood control, fisheries, and navigation. Besides these important benefits, dam failures can cause loss of life and financial loss. Safety risk analysis must be done for each dam and monitoring of dam situations examined continuously.The purpose of this study is to examine the safety of a dam in Turkey by performing risk analysis Firstly different dam safety researches are investigated and all available methods are searched. Dam failure parameters for different kinds of dams are identified. People who live in areas near dams, and the number of people affected in case of a possible collapse of the region are determined using maps and census data.For risk analysis purpose, an Excel based risk analysis tool was used. This tool was created by UTAH State University for the use of Federal Emergency Management Agency (FEMA). This software uses main dam characteristics such as dam height, body type, spillway capacity, mean annual precipitation, main steam length, and mean basin elevation. Risk analysis has been done by using critical parameters for each type of dam, for instance, important failure modes of earth fill dams are flood, earthquake, normal stability and piping.New features such as peak dam breach width, failure time formulas, peak breach discharge empirical formulas and breach side slope calculation methods are also added to the existing tool.In this study, risk assessment of a dam in Turkey has been made by using improved risk analysis software. As a result of risk analysis, hazard situations are classified on 3 different categories. These are high hazard, significant hazard and low hazard. Important risk parameters and failure results of these parameters are shown on graphics. New graphic results are drawn for new methods added on software. All graphical results are discussed Daha fazlası Daha az

Alper AYDEMİR

Bildiri | 2018 | 5th International Symposium on Dam Safety Proccedings 1 , pp.278 - 288

Bildiri

Mehmet Hasnalbant

Makale/Derleme | 2018 | Journal of Civil Engineering and Architecture

In order to investigate the behavior of buildings and engineering structures during earthquakes, based on the data of seismic observation devices mounted on constructions with typical characteristics, results of investigating the change of mechanical properties of building structural system over time and the results of examination of structural rigidity and safety change over time, depending on the dynamic characteristics of the building, determined by experimental investigations made at intervals are mentioned in this article. In addition, evaluation of earthquake acceleration acting on structures due to earthquake-induced damage . . .characteristics of buildings and engineering constructions which are made earthquake resistant is also included here. Daha fazlası Daha az

Haktanır T

Bildiri | 2018 | International Conference on Innovation, Sustainability, Technology and Education in Civil Engineering (İSTE-CE’2019) , pp.586 - 604

Using the measured data on 15 laboratory models in USA, six models and one prototype in Turkey, the discharge coefficients (C’s) of radial-gated ogee spillways for various gate openings and lake water surface elevations are computed. Comparison of these C’s for 22 spillways with the ones given by Figure 9-31 of Design of Small Dams does not show close agreements. It is determined that C depends on both the angle Ɵ and the ratio d/H1, rather than Ɵ only where d and H1 are the gate opening and the upstream head, and statistically significant regression equations are computed individually for each one of 22 cases.