The Effects of Reinforced Concrete Jacketing on the Earthquake Performance of Precast Structures

Ülkemizdeki sanayi yapıların çoğunluğunu, kolon-kiriş birleşim bölgelerindemoment aktarımı olmayan tek katlı prefabrike sistemleri oluşturmaktadır. Yaşanmışdepremler sonrasında yapılan gözlemler; prefabrike yapıların deprem etkisi altındayüksek yatay yerdeğiştirmeleri nedeniyle kolon-kiriş birleşim bölgelerinde ve yapıgenelinde önemli hasarların oluştuğunu göstermiştir. Bu tip yapı sistemlerinin depremekarşı güçlendirilmesi, sadece yüksek maliyetli cihazlar için değil öncelikli olarak insanyaşamı açısından hayati önem taşımaktadır. Bu çalışmada betonarme (BA) mantolamayönteminin prefabrike yapıların deprem performansındaki rolü sayısal olarakincelenmiştir. Çalışmanın ilk bölümünde, literatürde deneysel sonuçları yer alan BAmantolu ve mantosuz kolonların nümerik modelleri oluşturulmuştur. Tersinir tekrarlıyerdeğiştirme protokolü etkisi altında yapılan deneylerden elde edilen yükyerdeğiştirme ilişkileri, oluşturulan nümerik model sonuçları ile karşılaştırılmıştır.Nümerik modeller, belirli yerdeğiştirme eşikleri arasında deneysel sonuçları iyi birşekilde tahmin edilebilmektedir. Deneysel olarak kalibre edilmiş olan nümerik model, üçboyutlu sanayi tipi mevcut bir yapı sisteminin lineer olmayan dinamik analizlerindekullanılmıştır. Sayısal sonuçlar, mantolama sayesinde prefabrike yapının ortalama enbüyük ve en küçük göreli ötelemelerin %54 ile %72 arasında değişen oranlardaazaldığını göstermiştir. Mevcut yapının seçilen kolonları, birim şekildeğiştirme açısındandeğerlendirildiğinde; güvenlik sınırı (GV) civarında olan kesit performansının BAmantolama ile minimum hasar sınırının (MN) altına çekildiği görülmüştür.The majority of industrial buildings located in our country consist of single-story precast systems with pinned beam-to-column connections. Observations made after earthquakes showed that due to high lateral displacement demands occurred under the effects of earthquake loads; significant damage was accumulated throughout the beam-to-column connections and whole structure. Strengthening such building systems against earthquake loads is not only crucial for high-cost devices and machinery but also very important in terms of human life as a priority. In this study, the effects of reinforced concrete (RC) jacketing technique on the global earthquake performance of precast structures was examined numerically. In the first part of the study, experimental results of bare and RC jacketed columns, which exist in the recent literature, were used as a benchmark for the development of numerical models. The force-displacement relations obtained from quasi-static experiments were compared with the numerical results. The numerical models are successful to estimate the experimental results within the range of distinct displacement levels. Validated numerical models were used for nonlinear dynamic analysis of an existing 3D precast system. Numerical results showed that the application of RC jacketing technique is effective to decrease the average maximum and minimum drift values by the ratios of 54-72%. Determinations of strain levels for the selected columns of the system showed that; the RC jacketing retrofitting technique is effective to increase the sectional performance by shifting the strain demands from safety limit (GV) to minimum damage limit (MN)

Reinforcement Detailing Requirements For The Reinforced Concrete Structures In The Earthquake Region

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2002Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2002Bu çalışmada, deprem bölgelerindeki betonarme yapılarda donatı düzenlenmesinde dikkat edilmesi gereken genel kurallar ve donatı hususlarında yapı elemanlarında uyulması gereken minimum koşullar, yönetmelikler paralelinde sebepleri ile beraber incelenmiştir. Donatıların yerleştirilme biçimleri, yapıların yük altındaki davranış şekillerini etkilemektedir. Betonarme yapı elemanlarında donatının doğru olarak yerleştirilmesi için, yapı elemanlarının çeşitli yüklemeler altındaki şekil değiştirme durumunun bilinmesi gerekmektedir. Şekil değiştirme durumunun bilinmesi ile donatının teorik yeri belirlenebilmektedir. Taşıyıcı betonarme yapı elemanın yükler altında uygun davranış gösterebilmesi için teorik olarak donatının gerilme yörüngelerine paralel olarak yerleştirilmesi gerekmektedir. Dolayısıyla bu çalışma sırasında yapı elemanlarının yükler altındaki deformasyon şekli ve buna paralel olarak da donatı düzenleme ilkeleri incelenmiştir. Bu tez kapsamında yapıların güvenliğinde hayati önem taşıyan donatı detaylandırma ilkeleri davranış bilgisi ile beraber verilmiştir. Sonuç olarak donatı detaylandırılmasında yapıların yük altındaki deformasyon şekillerine uyulması ile en uygun betonarme davranışı sağlanmış olacaktır. Donatıların konumları iyi tayin edilmeli ve yerli yerine yerleştirildiği iyi denetlenmelidir. Aksi halde tasarım aşamasında harcanmış tüm emekler boşuna gidecektir. Donatı düzenleme kalitesinin artması için çeşitli kesme ve bükme makineleri kullanılmalı ve bu makinelerle tasarruf edilen zaman, donatı düzenlemesinde kullanılmalıdır. Böylelikle daha özenli yapılar yapılması sağlanacaktır. Yapıların deprem yükleri altında iyi davranış sergileyebilmesi için, yapılar güvenli olarak projelendirilmiş olmalı ve projenin yerinde titizlikle uygulandığı da iyi denetlenmiş olmalıdır.In this study the general reinforcement detailing rules regarding with the reinforced concrete structures in the earthquake region and the minimum requirements for the reinforced concrete structural elements have been investigated with their reasons and parallel to the Turkish Codes. The way of reinforcement detailing, also affects the behavior of the structures under load. In order to apply a good reinforcement detailing in the structural elements, the behavior of the elements under load must be known very well. The theoretical position of the reinforcement can be determined by investigating of the deformation shape of the element. Theoretically, the reinforcements of the elements must be positioned parallel to the stress directions, so that the structural elements will behave well under load. Because of this, in this study, the deformation shape of the elements under load and with parallel to this, the reinforcement detailing requirements are investigated. The detailing requirements that carry a vital importance in the structure’s security, is given composed with the behavior knowledge in this study. As a result, if the way is followed that the structure is deformed under load, than the best behavior of the structures are obtained. The positions of the reinforcements must be determined and inspected very well. Other wise, all the calculations at the designing stage will be just waste of time. In order to increase the quality of the detailing, reinforcement bending and cutting machines must be used. The time that is saved from cutting and bending can be used in detailing the reinforcement. Consequently, the structures can be built-up more carefully and healthy. In order to built-up earthquake resistant structures, the designing projects must be prepared carefully and the inspection of the application must be done very well.Yüksek LisansM.Sc

Enerji tüketebilen çelik yastıkların tipik bir betonarme çerçeve davranışına etkisi

Betonarme çerçeve tipi yapıların deprem davranışları, enerji tüketebilen metal elemanlar kullanılarak iyileştirilebilmektedir. Metal elemanlar, yapının çerçeve gözlerine yerleştirildiğinde yapıya giren deprem enerjisini plastik deformasyon yaparak tüketebilmektedir. Yeni nesil yapı tasarımı, plastik şekil değiştirmelerin yapısal elemanlardan çok, deprem sonrasında yenisiyle değiştirilebilen metal elemanlarda yoğunlaşması sağlanarak hasarının azaltılması eğilimindedir. Bu çalışmada enerji tüketme özelliği olan farklı kalınlıklardaki yastık görünümlü metal elemanların çevrimsel davranışı, deneysel ve analitik olarak incelenmiştir. Farklı kalınlıklardaki çelik yastıkların kayma deneyleri İstanbul Teknik Üniversitesi Yapı ve Deprem Mühendisliği Laboratuvarında (STEELAB) gerçekleştirilmiştir. Çelik yastıklar için analitik model geliştirilmiş ve gerçek betonarme yapıdan çıkartılmış bir çerçevenin lineer olmayan analizinde kullanılmıştır. Analiz sonuçları, levha kalınlığına bağlı olarak çelik yastıkların betonarme çerçeve dayanımını %5 ile %20 arasında değişen oranlarda artırdığını göstermektedir. Kalınlığı 18 mm olarak seçilen çelik yastığın kullanıldığı betonarme çerçeve yalın çerçeveden 5 kat daha fazla enerji tüketmiştir. Aynı kalınlıktaki çelik yastık, çerçeve sistemin toplam enerjisinin %55’ini tüketmiştir

İstanbul’un Esenler İlçesinde yer alan Betonarme Yapıların Sismik Hasar Görebilirliğinin Değerlendirilmesi

Istanbul is one of the largest cities of Turkey which is located on the regions where there is high seismic activities. Recent studies performed on mid-rise reinforced concrete (RC) structures showed that majority of the existing building stock does not conform to current seismic code requirements and they can be evaluated as vulnerable structures. The seismic performance evaluation of an existing buildings can be conducted by using nonlinear procedures stated in Turkish Earthquake Code (TEC-07). According to the code, an existing building completing its economic lifetime and/or having a performance level in between “Life Safety” to “Collapse Prevention” under the effect of Design Earthquake is defined as “building under seismic risk”. Before going into such a detailed seismic evaluation procedure for each building, there is a need for regional screening surveys to rank the building stock in terms of the potential seismic hazard. This study aims to assess the seismic vulnerability of a group of midrise RC buildings located in Esenler District of İstanbul employing the Rapid Visual Screening (RVS) procedure. In this study, valuable results have been derived to rank the buildings in terms of seismic vulnerability of existing structures located in Istanbul. It is concluded that the number of stories is the key parameter to change the priority range of the building from lowest to highest level. Majority of the buildings with the highest priority level (0≤PS≤30) suffer from the parameters related with poor construction quality, soft story irregularity and the heavy overhang. The aforementioned method could be used to estimate the performance scores of the buildings to determine the priority for more detailed seismic risk assessment procedures.İstanbul, Türkiye'nin sismik aktivitesi yüksek olan en büyük şehirlerinden biridir. Orta yükseklikteki betonarme yapılar üzerinde yapılan son çalışmalar, mevcut bina stokunun çoğunluğunun güncel deprem yönetmeliği şartlarına uymadığını dolayısıyla hasar almaya meyilli yapılar olarak değerlendirilebileceğini göstermiştir. Mevcut binaların deprem performansının değerlendirilmesi, Türk Deprem Yönetmeliği (TEC-07)'de belirtilen lineer olmayan yöntemler kullanılarak yapılabilir. Mevcut yönetmeliğe göre, ekonomik ömrünü tamamlayan ve/veya tasarım depremi etkisinde performans seviyesi "Can Güvenliği" ile "Göçmenin Önlenmesi” arasında bulunan yapı, "riskli bina" olarak tanımlanmaktadır. Her bina için böylesine detaylı bir deprem değerlendirme yöntemine gerek kalmadan, bina stokunun potansiyel sismik tehlike açısından sıralamak amacıyla bölgesel tarama anketlerine ihtiyaç duyulmaktadır. Bu çalışma, İstanbul Esenler İlçesi'nde bulunan bir grup orta yükseklikteki betonarme binanın “Hızlı Görsel Tarama (RVS)” yöntemini kullanarak deprem güvenliğini belirlemeyi amaçlamaktadır. Bu çalışmada İstanbul'da bulunan mevcut yapıların deprem güvenliğine göre sıralandırılması açısından önemli sonuçlar elde edilmiştir. Kat adedinin, yapının potansiyel risk seviyesini en düşükten en yükseğe değiştirebilen bir anahtar parametre olduğu sonucuna varılmıştır. Kötü inşaat kalitesi, yumuşak kat düzensizliği ve ağır çıkma ile ilgili parametreler, en yüksek risk seviyesine sahip olan binalarda (0≤PS≤30) ortak zafiyetler olarak belirlenmiştir. Söz konusu yöntem, daha detaylı deprem riski değerlendirmesi için önceliğin belirlenmesi amacıyla binaların performans puanlarını tahmin etmekte kullanılabilmektedir

Determination of the Risk on Human Health of Heavy Metals Contained by Ship Source Bilge and Wastewater Discharged to the Sea on the Mediterranean by Monte Carlo Simulation

Discharge of bilge and wastewater from ships into the sea poses a risk to human health due to the heavy metals. In this study, shipborne bilgewater and wastewater carcinogenic and non-carcinogenic human health risks determine by using the measured and literature values of heavy metals copper, iron, vanadium, chromium, manganese, cobalt, nickel, zinc, arsenic, cadmium, and mercury in the shipborne bilgewater and wastewater. The heavy metal contents of seawater were selected from 11 points determined in Antalya Bay, wastewater, and bilge samples taken from two ships. The human health risk was determined using the Monte Carlo Simulation (MCS) method using these measured values and the heavy metal concentrations in the Mediterranean Sea in the literature. The risk of carcinogenicity of heavy metals from wastewater by dermal route, ingestion, and from bilge water by dermal way and ingestion were evaluated. The wastewater is dermal Ni > As > Cr, the wastewater is Ni > Cr > As by ingestion, the dermal Ni > As > Cr in the bilge, and the risk of ingestion is Ni > Cr > As. It has been determined that the non-carcinogenic Cr, Co, Hg, and As values in the wastewater and bilge water are above the acceptable 1 and therefore expose a risk to human health. The human health carcinogenic risk caused by heavy metals generating from the bilge and wastewater is much higher than the standard values determined by the WHO. For the first time in this study, it was determined that bilge water exposes a high risk for both swimmers and ship personnel in the health risk assessment of shipborne wastewater and bilge water

Improvement of seismic performance of precast frames with cladding panels fastened by energy dissipative steel cushions

Precast reinforced concrete panels are commonly used as wall claddings in precast buildings. The cladding panels are generally evaluated as non-structural members and are joined to structural systems via mechanical, welding, and bolted dry connections. Several failures were observed in the last seismic events in Southern Europe, which demonstrate the deficiencies of the cladding connections in terms of strength and ductility. A comprehensive research activity named SAFECLADDING was conducted in Europe to provide knowledge for proper seismic design of precast structures with cladding panels. In this context, energy dissipative steel cushions were developed and evaluated through the extensive experimental and numerical studies. Steel cushions can provide robust interaction of the structural system with the cladding panels. This paper numerically evaluates the effects of cladding panels with steel cushions on the global seismic behaviour of the buildings. An existing representative industrial building is selected to perform intensive nonlinear dynamic analyses. Analyses performed on the bare and hybrid systems showed that the hybrid system has high performance in terms of story drifts, internal forces, and deformations with respect to the bare system. The overall drifts in longitudinal and transversal directions of the building are reduced by about 78 and 54%, respectively. Average residual drifts of cladding panels and steel cushions indicated that the applied steel cushion placement scheme has a promising re-centring capability during seismic action.The research presented herein was accomplished via the valuable experimental and numerical data derived FP7 project, "SAFECLADDING: Improved Fastening Systems of Cladding Wall Panels of Precast Buildings in Seismic Zones" research for SME associations, grant agreement number 314122, coordinated by Mr. Alessio Rimoldi from BIBM, Belgium. The financial support provided by the Commission of the European Communities through SAFECLADDING and other project partners are greatly acknowledged. The study was conducted at the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University. Support for the laboratory staff and graduate students is gratefully acknowledged.Publisher's Versio

Cyclic behavior of reinforced concrete cladding panels connected with energy dissipative steel cushions

Precast concrete structures show damage after the destructive earthquakes and indicate that the connections of reinforced concrete (RC) cladding panels might be inadequate. RC cladding panels greatly increase the lateral stiffness and strength of the building when they are rigidly connected to the structural system. However, this also increases the seismic requirements. Consequently, a robust mechanical connection device with energy-dissipating capability was produced for RC cladding panels. Extensive experimental and numerical studies on an energy-dissipative steel cushion (SC) connection device were carried out in the framework of the SAFECLADDING project. Cladding panel tests were conducted with various connection configurations. The fundamental variables are the location, quantity, and thickness of SCs used in the cladding systems. The test results demonstrate that the SCs used in panel-to-panel and panel-to-support connections made large contributions to the total energy dissipation capacity. The parameters of a numerical model were also evaluated to reproduce the experimental results.This research was conducted in the framework of the FP7 project, "SAFECLADDING: Improved Fastening Systems of Cladding Wall Panels of Precast Buildings in Seismic Zones," research for SME associations, grant agreement number 314122, which was coordinated by Mr. Alessio Rimoldi from BIBM. The financial support provided by the Commission of the European Communities through this project is greatly appreciated. The study was conducted at the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University. The support of the laboratory staff and graduate students is gratefully acknowledgedPublisher's Versio

Uni-axial behavior of energy dissipative steel cushions

Seismic excitations may impart a significant amount of energy into structures. Modern structural design attitudes tend to absorb some part of this energy through special dissipaters instead of heavy plastic deformations on the structural members. Different types of dissipater have been generated and utilized in various types of structures in last few decades. The expected earthquake damage is mainly concentrated on these devices and they may be replaced after earthquakes. In this study, a low-cost device called energy dissipative steel cushion (EDSC) made of flat mild steel was developed and tested in the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University (ITU). The monotonic and cyclic tests of EDSC were performed in transversal and longitudinal directions discretely. Very large deformation capability and stable hysteretic behavior are some response properties observed from the tests. Load vs. displacement relations, hysteretic energy dissipation properties as well as the closed form equations to predict the behavior parameters are presented in this paper.The research presented herein was conducted in the framework of the FP7 project "SAFECLADDING: Improved Fastening Systems of Cladding Wall Panels of Precast Buildings in Seismic Zones" research for SME associations, grant agreement number 314122, which was coordinated by Mr. Alessio Rimoldi from BIBM. The financial support provided by the Commission of the European Communities through this project is greatly appreciated. The study was conducted at the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University. The support of the laboratory staff and graduate students is gratefully acknowledgedPublisher's Versio

Experimental investigation and pseudoelastic truss model for in-plane behavior of corrugated sandwich panels with polyurethane foam core

Sandwich panels are commonly used in facades and the roofs of industrial buildings due to their well-known advantages. However, there is limited data about the in-plane behavior of the panels. Hence, this paper aimed to propose a pseudoelastic truss model to represent the effective in-plane stiffness and strength properties of the corrugated sandwich panels with a polyurethane foam core. Two separate sets of experiments (mock-up and system test) were conducted in the laboratory. The variables were the number of fasteners, sheet thickness, loading direction, and number of ribs. The number of fasteners, sheet thickness, and loading direction are the most effective parameters for the in-plane behavior. A formula was proposed to compute axial stiffness of the truss members by considering the effective parameters. Experimental results showed that the proposed robust truss model could give a good estimate of the pseudoelastic stiffness and maximum load bearing capacity of the sandwich panels.Turkish Precast Concrete AssociationThis study was conducted in the framework of ITuNOVA Technology Transfer Office Research Project titled Determination of In-plane Behavior of Corrugated Sandwich Panel Type Roof Shelters. The finan-cial support provided by Turkish Precast Concrete Association through this project is greatly appreciated. The study was conducted at the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University. Support of the laboratory staff and the contributions of Gunkut Barka and Hakan Atakody are gratefully acknowledged

Behaviour of steel cushions subjected to combined actions

Mild steel is relatively low-cost and easily accessible material to fabricate some structural members. It would be a significant advantage if seismic energy dissipaters that are used in structures constructed in the earthquake prone areas, could also be produced on site. In this paper, a promising seismic energy dissipater made of mild steel, so-called steel cushion (SC) is presented. It is provided experimental and analytical responses of SCs subjected to bi-axial loadings. SC rolls under the lateral loading that allows relocation of the plasticized cross-section. Henceforth, SC dissipates considerable amount of seismic energy. A series of tests were performed to achieve experimentally the behavior of SC subjected to longitudinal and transversal loading. Finite Element Models (FEMs) were also generated to reproduce the experimental backbone curves and to predict the bi-directional response properties for discrete transversal forces and plate thicknesses. Closed-form equations were derived to determine yield and ultimate forces and the corresponding displacements as well as location of the plasticized sections. The behavior of SC could either be projected by the FEMs with the exhibited parameters or by means of the proposed closed-form equations and the normalized design chart