5 research outputs found
Investigation of the effects of cyclic lateral load characteristics on monopiles in saturated sandy soils using hypoplastic material model
No full text<p>Offshore wind turbines play a critical role as a renewable energy source and are experiencing continuous growth in usage. Both the design and implementation phases of constructing these structures present difficulties. It is crucial to ensure these structures are built to resist such conditions, assuring their durability, as they are exposed to lateral external influences such as wind and wave loads. This study investigated how monopile foundations behave in saturated sandy soil under cyclic loading. Pore water pressure accumulations in saturated sandy soil, monopile head lateral displacements, and vertical settlements around the monopile are investigated using the hypoplastic material model and two-phase element with the ANSYS finite element program. Analyses conducted in this study demonstrated that lateral cyclic loads could cause excessive pore water pressure accumulations around the monopile, leading to displacements in the monopile head and soil settlements around it, highlighting the importance of carefully considering loading characteristics during the design process to provide the security and longevity of offshore wind turbines.</p>
ÇELİK CÜRUFU İLE İMAL EDİLEN TAŞ KOLONLARIN SAYISAL ANALİZİ
No full textSıvılaşma kaynaklı hasarları önlemede en etkin çözümlerden biri taş kolon uygulamalarıdır. Zemin iyileştirme amacıyla uygulanan taş kolon uygulamalarında hem zeminlerin drenaj kapasitesi hem de rölatif sıkılıkları arttırılmaktadır. Böylece dinamik yükler altında oluşan aşırı boşluk suyu basıncı azalmakta ve sıvılaşma nedeniyle oluşan hasarlar en aza indirilmektedir. İnşaat Mühendisliği’nde yaygın bir şekilde kullanılan sonlu elemanlar yönteminde zemin davranışı ileri düzey zemin modelleri kullanılarak modellenebilmekte, zeminde oluşan deformasyonlarla gerilme dağılımları daha gerçekçi olarak belirlenebilmektedir. Sonlu elemanlar yöntemiyle yapılmış olan bu çalışmada yapılan analizlerde dinamik yüklemeler altında boşluk suyu basıncı oluşumlarını görebilmek için hipoplastik malzeme modeli kullanılmıştır. Ancak ANSYS sonlu elemanlar programında tanımlı olmayan bu modelin kullanımına olanak sağlanması için programa üç boyutlu iki fazlı bir eleman (u20p8) tanımlanmıştır. Geliştirilen bu eleman için iki fazlı model temel alınmıştır. Çalışmada taş kolon malzemesine alternatif olarak, bazik oksijen fırınlarından (BOF) elde edilen, çelik üretim işlemi atık malzemelerinden olan, çelik cürufu kullanılmıştır. Çelik cürufu, erimiş demirin istenmeyen elementlerden arındırılması sırasında çelik üretim sürecinde elde edilen çelik fabrikalarının yan ürünlerinden biridir. Çelik cürufu kolonların dinamik yükler altında zeminlerdeki sıvılaşmayı önleyici etkisi incelenmiş ve yapılan analizlerde performanslarının taş kolonlara nazaran bir miktar daha düşük olmasına rağmen uygun tasarımlar elde edilerek kullanılması durumunda alternatif olarak kullanılabileceği görülmüştür. Ayrıca taş ve çelik cüruf kolonlar için parametrik analizler yapılarak alan oranı, hidrolik iletkenlik ve rölatif sıkılık gibi parametrelerin performanslarını arttırdığı tespit edilmiştir. Bu çalışmayla, doğada atıl olarak istiflenen çelik cürufları için yeni bir kullanım alanı açılarak endüstriyel atıkların geri dönüşümüne katkıda bulunulması hedeflenmiştirOne of the most effective solutions to prevent liquefaction-induced damage is stone column applications. With stone column applications both the drainage capacity and the relative density of the soils increase. Thus, excessive pore water pressure created under dynamic loads is reduced and damage caused by liquefaction is minimized. In the finite element method, which is widely used in Civil Engineering, soil behavior can be modeled by using advanced soil models, and stress distributions can be determined more realistically with the deformations in the soil. The hypoplastic material model was used to see pore water pressure formations under dynamic loads in the analyzes performed in this study. However, a three-dimensional two-phase element (u20p8) has been defined in the program to enable the use of this model, which is not defined in the ANSYS program. In the study, steel slag obtained from basic oxygen furnaces (BOF), which is one of the waste materials of the steel production process, was used as an alternative for the stone column material. It is one of the by-products of steel mills obtained in the steel production process during the purification of molten iron from unwanted elements. The effect of steel slag columns to prevent liquefaction in soils under dynamic loads has been investigated and it has been observed that although the performance of them is slightly lower than that of stone columns, they can be used as an alternative if appropriate designs are obtained and used. In addition, by performing parametric analysis for stone and steel slag columns, it has been determined that parameters such as area ratio, hydraulic conductivity and relative density increase their performance. With this study, it is aimed to contribute to the recycling of steel slags by opening a new area of using for them
Analysis of Stone Column Performance with Hypoplastic Model
No full textIn soft soils, soil liquefaction and related ground changes constitute a large part of the damages occurred due to the earthquakes in past years. One of the methods used to prevent the occurrence of these damages is the stone column method whose importance is increasing every day. Despite the studies, the working behaviour of stone columns under dynamic loading continues to be a complex issue. In this study, the performance of stone columns in loose, saturated sandy soils was investigated with a three dimensional finite element model. In the analysis, both pore water pressure ratios and settlement results were compared for soils with and without stone columns. Also a parametric study is carried out to see how changes in stone column parameters affect stone column performance. A three-dimensional two-phase element (u20p8) implemented to ANSYS program to make the usage of hypoplastic material model possible, in order to obtain pore water pressure accumulations that may occur under dynamic loading in saturated soils. It is seen that the model is well suited for the examination of the behaviour of granular soils under repeated loading. In this study, the advantages of using stone columns in saturated granular soils were discussed. This study is useful for the further studies to see the effect of stone column applications in liquefaction susceptible soils
Arterial carbon dioxide markedly increases during diagnostic laparoscopy in portal hypertensive children Author(s): Bozkurt, P; Kaya, G; Yeker, Y; et al. Source: ANESTHESIA AND ANALGESIA Volume: 95 Issue: 5 Pages: 1236-1240 DOI: 10.1213/01.ANE.0000030426.38778.EB Published: NOV 2002
No full textEsophageal variceal bleeding secondary to portal hypertension: Endoscopic sclerotherapy as the first-step treatment Author(s): Yesildag, E; Emir, H; Tekant, G; et al. Source: JOURNAL OF LAPAROENDOSCOPIC & ADVANCED SURGICAL TECHNIQUES-PART A Volume: 12 Issue: 3 Pages: 199-202 DOI: 10.1089/10926420260188100 Published: JUN 2002
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