Cam Elyaf İçeren Betonarme Kirişin Eğilme Davranışı İçin Deneysel Çalışma

Konferans Bildirisi-- İstanbul Teknik Üniversitesi, Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2017Conference Paper -- İstanbul Technical University, Theoretical and Applied Mechanical Turkish National Committee, 2017Yaygın yapı malzemesi olarak kullanılan beton gevrek bir malzeme olduğu için basınç altında nispeten güçlü olmasına rağmen çekmede zayıftır [1, 2]. Betonun çekmedeki zayıflığı, geleneksel çelik çubuk takviyesinin kullanılması veya yeterli oranda lifli malzemenin karıştırılmasıyla aşılabilmektedir [3]. Liflerin kullanımı, betonda çatlaklar oluştuktan sonra da kompozit malzemenin tokluğunu arttırarak davranışını yeniden düzenler. Lifli beton küçük ve süreksiz elyafların düzgün şekilde dağılmış olduğu betondur. Mevcut araştırmada, ince agrega yerine cam elyafın farklı oranlarda (% 0.0, % 0.5, % 1.0, % 1.5) eklenmesi ile, betonun basınç dayanımını, eğilme mukavemetini ve işlenebilirliliğini araştırmak için deneysel çalışmanın yapılması amaçlanmaktadır. Cam elyafın C30 kalite betonun basınç, çekme ve eğilme mukavemeti üzerine etkileri karşılaştırılacaktır. Her lif yüzdesi için, ortalama sonuçları almak için üçer adet küp ve silindir numune dökülmüştür. Ayrıca betonarme kirişin, eğilmede güçlendirmesini incelemek için de dört adet 1300 mm etkin açıklıklı kirişde dört noktalı eğilme testi yapılacaktır.Concrete is most widely used construction material in the world. It is relatively strong in compression but weak in tension tends to be brittle [1, 2]. The weakness in tension can be overcome by the use of conventional steel reinforcement and to some extent by the mixing of a sufficient volume of certain fibers [3]. The use of fibers also recalibrates the behavior of the fiber-matrix composite after it has cracked through improving its toughness. Fiber reinforced concrete is a concrete in which small and discontinuous fibers are dispersed uniformly. In the present investigation, the compressive strength, flexural strength, and workability of concrete containing varying proportions of Glass Fiber (GF) (0.0 %, 0.5 %, 1.0 %, 1.5 %) as replacement of fine aggregate is studied. The effect of GF on C30 concrete on compressive strength, tensile strength and flexural strength are studied for a given aspect ratio and various percentages of GF. For each percentage of fiber three cubes and three cylinders are casted to take average results. Also for flexural strengthening of reinforced concrete, four beams were tested over an effective span of 1300 mm up to the failure of the beam under four-point loading test

Analysis and Optimum Design of Curved Roof Structures

Curved steel buildings are frequently designed to supply the users of the structure with ordinary light with a sense of capaciousness as well as grandness in public facilities such as stations, buying malls, leisure centres and airports. This paper presents a method for analysis and optimum design of 2D and 3D curved roof trusses subjected to static loading and specified set of constraints. Here the optimization refers to minimization of total weight of curved roof structures such that they can resist applied forces (stress constraint) and don’t exceed certain deformations (displacement constraints). The finite element formulations is developed and implemented for the static analysis of curved roof trusses to determine the stresses and displacements. The use of a reliable and competitive procedure for finding the optimum solutions for problems involving continuous design variables based on genetic algorithms is demonstrated and used in this study .The performance of genetic algorithms is affected by various factors such as coefficients and constants, genetic operators, parameters and some strategies. Member grouping and initial population strategies are also important factors. Optimization is an automated design procedure in which the computers are utilized to obtain the best results. The numerical methods of structural optimization with applications of computers automatically generate a near optimal design (converge to solve) in interactive manner. A program was modified and used to automate analysis and optimization of the structure written in FORTRAN language based Finite Element analysis and Genetic Algorithm optimization technique. The developed method is tested on several examples and compared with previous researches or SAP2000 results. It is concluded that this method can serve as a useful tool in engineering design and optimization of curved roofs

Panellerin Burkulma Analizinde Yapay Sinir Ağları Yaklaşımı

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2008Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2008Bu bildiride panellerin burkulma analizi sonlu şeritler metodu ve yapay sinir ağları yaklaşımı ile incelenmektedir. Mindlin-Reissner kabuk teorisine bağlı sonlu şeritler metoduyla geliştirilen bilgisayar programı kullanılarak farklı panel boyutları için kritik burkulma yükleri hesaplanmış ve elde edilen veriler önerilen yapay sinir ağları modelini eğitmek için kullanılmıştır. Kullanılan analiz tekniğinin ve önerilen yapay sinir ağları modelinin geçerliliği çeşitli örneklerle gösterilmiştir.This paper deals with the analysis of stiffened panels in buckling situations using finite strip and Neural Network approach. The finite strip method is used to determine the critical buckling loads based on Mindlin-Reissner shell theory which is further used for the training of the proposed Neural Network Model. The validation of the analysis and the proposed Neural Network model is also shown by means of several examples of application

Modelling of Bonded Post-Tensioned Concrete Cantilever Beams under Flexural Loading

Prestressing is widely used technic all over the world for constructions of buildings, bridges, towers, offshore structures etc. due to its efficiency and economy for achieving requirements of long span with small depth. It is used for flexural strengthening of reinforced concrete structures for improving cracking loads and decreasing deflections due to service loads. There are two methods for prestressing (pre-tensioning and post-tensioning). In this paper, a three-dimensional nonlinear Finite Element (FE) method is used to determine the behaviour of Post-Tensioned (PT) concrete cantilever beams with different tendon profiles. Numerical analyses ANSYS package program is used for analysis of beams. The results from FE analysis is verified by experimental reference test result and good agreement is achieved. This paper is focused on the effect of different tendon profiles on the flexural behaviour of Bonded Post Tensioned (BPT) reinforced concrete cantilever beams. Six models with different tendon profiles are investigated. These models are without tendons, two tendons at the bottom, middle, top, parabolic tendons with one draped point and two draped points. Failure loads, deflections, and load versus deflection relationships for all models are examined and it is seen that the beam with one draped tendon profile shows a highest performance

Investigation Of Ductility Of Pva Fiber Reinforced Beams

The current work aims to investigate the behaviour of PVA fibre reinforced beams under four-point flexural test in which the judgment is based on the peak load resistance and the ductility. To achieve this aim, four beams, which are reinforced with PVA fibres and conventional reinforcement bars are tested. Three fibre percentages (0.5, 1.0, and 1.5 %) are used, the behaviour of these beams are compared with the control beam of plain concrete. The results showed that the inclusion of 0.5 % of fibre increases the compressive strength by 48 %, the first cracking load by 104 %, and the ultimate strength by 10 %. And also, the inclusion of 1.5 % of PVA increases the beam ductility factor by 63 %. Moreover, the mentioned improvements are also affects the load initiate the first crack and crack depth of the compression zone, where the load resistance of the compression zone is increased by 8 % for that beam with 1.5 % of PVA compared to the beam of plain concrete.İT

Enerji iletim Hattı Direklerinin Genetik Algoritma ile Optimizasyonu

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2011Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2011Bu çalışma, enerji iletim hatlarında kullanılan direklerin statik yükler altındaki şekil optimizasyonu üzerinedir. Yapı maliyetleri ancak yapıyla ilgili detaylı bilgilerin edinilmesi ve tasarımların iyileştirilmesi ile minimize edilebilir. Statik yüklere maruz direklerdeki gerilme ve yer değiştirmeler sonlu elemanlar metodu ile hesaplanmıştır. Optimum tasarım için sonlu elemanlar metodu ile genetik algoritma metotlarını birleştiren bir modüler bilgisayar programı geliştirilmiştir. Örneklerde üç boyutlu birkaç tip enerji iletim direkleri seçilerek, şartnamelerdeki yükler altında kesit alanları değişkenleri kullanılıp, optimizasyonunun verimliliği gösterilmiştirThis paper deals with the size optimization of electric povver transmission towers under static loads. Minimizing the cost of structures can only be accomplished by increased knowledge of loading conditions which influence the possible risks involved. The finite element method is used to determine the stress and displacements of truss structures which are under the static loads. For optimum design a modular Computer program is derived to combine the finite element method and genetic algorithm. Three dimensional povver transmission towers are dealt and size design variables are used to demonstrate the efficiency of optimization program