Recent perspectives for ferrocement |
Author : Ornela Lalaj; Yavuz Yardim; Salih Yilmaz |
Abstract | Full Text |
Abstract :Ferrocement is the oldest form of the reinforced concrete, dating back two centuries. It is composed of mortar and galvanized steel wire mesh. It is used for a wide range of application including construction of boats, water tanks, slabs and roofs, and lining of tunnels. Nowadays, reinforced concrete is widely known and used material, whereas ferrocement has limited applications. Properties such as high strength/weight ratio and good resistance to cracking and impact loadings are bringing ferrocement under the spotlight again. New applications have been developed in the recent years, such as low cost dwelling buildings and strengthening of a wide variety of structural elements. However, these applications are still in their first stages. The aim of this paper is to summarize existing literature on the use of ferrocement and to discuss new applications of ferrocement.
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Response of an isolated structure with deteriorating hysteretic isolator model |
Author : Gökhan Özdemir; Beyhan Bayhan |
Abstract | Full Text |
Abstract :Cyclic motion of lead rubber bearings (LRBs) leads to increasing temperature in lead core initiating the reduction in strength of LRB. This reduction results in a deteriorating bi-linear force deformation relation for LRB. In this study, response of LRBs (with deteriorating hysteresis loops due to temperature change) subjected to near-field ground motions with distinct pulse-type behavior is studied. Ground motions are applied bi-directionally and LRBs are modeled with due consideration of coupled behavior in the two orthogonal horizontal directions. Response of LRBs with deteriorating hysteresis is compared with that of non-deteriorating ones by considering bounding analyses (upper and lower bound). Thus, nonlinear response history analyses are performed for each selected ground motion record. Bounding analyses result in over predicted displacement demands for LRBs compared to results obtained by implemented deteriorating bi-linear LRB model. By means of new deteriorating model, engineers may come up with more efficient isolation system designs. |
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Free vibration and bending of functionally graded beams resting on elastic foundation |
Author : Seref Doguscan Akbas |
Abstract | Full Text |
Abstract :In this paper, free vibration and static bending analysis of functionally graded (FG) beams resting on Winkler foundation are investigated within Euler-Bernoulli beam theory and Timoshenko beam theory. Material properties of the beam change in the thickness direction according to power-law distributions. The governing equations and the related boundary conditions are derived using the principal of the minimum total potential energy. The Navier-type solution is used for simply-supported boundary conditions, and exact formulas are proposed for the static deflections and the fundamental frequencies. In order to establish the accuracy of the present formulation and results, the natural frequencies are obtained, and compared with the published results available in the literature. Good agreement is observed. Numerical results are presented to investigate the influences the different material distributions, foundation stiffness, and shear deformation on the bending and free vibration behavior of FG beams. |
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Estimation of shear force for blind shear ram blowout preventers |
Author : Abdulkadir Tekin; Changhyok Choi; Taylan Altan; Hamit Adin |
Abstract | Full Text |
Abstract :In this study, the estimation of shear force for blind shear ram type blowout preventer was investigated by using Finite Element Method (FEM). So, the effect of the blowout preventer working condition on shear force requirement for shear operation could be accurately approximated by simulating the entire process, and ram geometry could be optimized to reduce force and energy used to shear the tube by plastic deformation. The results of FEM analyzes was compared with blowout preventer manufacturer shear force information. Comparisons show that forces evaluated by using FEM (Deform 3D) simulations provided fairly accurate results for actual shear force. Also, it was found that by using Finite Element simulations the effect of the blowout preventer working condition on shearing operation can be estimated and ram geometries can be optimized. Therefore, FEM analyses could be used to design more reliable and efficient ram type blowout preventers. |
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A model for shear behavior of anchors in external shear walled frames |
Author : Iffet Feyza Çirak; Hasan Kaplan; Salih Yilmaz; Özlem Çaliskan Degirmenci; Nihat Çetinkaya |
Abstract | Full Text |
Abstract :Retrofit of the existing seismically deficient buildings is a common need especially in earthquake prone regions. Chemical anchors are widely used to connect existing and newly added structural elements, such as shear walls. Therefore, modelling the behaviour of anchors which transfer axial and shear forces to the added members is important for design and analyses. There is no anchor model present in the current literature accounting shear behaviour. Therefore, a new model is established using results of a comprehensive experimental study conducted at Pamukkale University Earthquake and Construction Technology Research Laboratory. In this study, mentioned shear model is tested using two- story, one-bay RC frame specimens strengthened with external shear walls. In analyses of the models, SAP 2000 software is used and nonlinear shear behaviour of anchors is represented by NLLink elements. It is concluded that, suggested anchor shear model may be used for modelling external shear wall anchor behaviour. |
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