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CONTENTS
Volume 3, Number 2, June 2015
 

Abstract
In this paper, the load-deflection analysis of the Carbon Fiber Reinforced Polymer (CFRP) strengthened Reinforced Concrete (RC) slab using Recurrent Neural Network (RNN) is investigated. Six reinforced concrete slabs having dimension 1800X400X120 mm with similar steel bar of 2T10 and strengthened using different length and width of CFRP were tested and compared with similar samples without CFRP. The experimental load-deflection results were normalized and then uploaded in MATLAB software. Loading, CFRP length and width were as neurons in input layer and mid-span deflection was as neuron in output layer. The network was generated using feed-forward network and a internal nonlinear condition space model to memorize the input data while training process. From 122 load-deflection data, 111 data utilized for network generation and 11 data for the network testing. The results of model on the testing stage showed that the generated RNN predicted the load-deflection analysis of the slabs in acceptable technique with a correlation of determination of 0.99. The ratio between predicted deflection by RNN and experimental output was in the range of 0.99 to 1.11.

Key Words
CFRP; RC; RNN; MATLAB

Address
S.V. Razavi : Jundi-Shapur University of Technology, Dezful, Iran
Mohad Zamin Jumaat : Civil Engineering Department, University Malaya(UM), Malaysia
Ahmed H. El-Shafie : Civil Engineering Department, Universiti Kebangsaan Malaysia(UKM), Malaysia
Reza Ronagh : School of Civil Engineering, The University of Queensland, Australia

Abstract
The foam concrete was fabricated by adding the foaming agent which composite ordinary Portland cement with plant and animal protein into cement paste, and the electromagnetic wave absorption properties were studied for the first time as well. The studies showed that the electromagnetic waves can be absorbed by multiple reflections and scattering within the porous material. Thickness and filling ratio have a great influence on the electromagnetic wave absorbing properties in 2-18 GHz of the foam concrete, the greater the thickness, the better the performance of absorption; filling ratio was about 52 vol.%, the absorbing properties achieved the best.

Key Words
foam concrete; microwave absorbing; filling ratio; thickness

Address
Lv Xingjun, Cao Mingli, Li Yan, Li Qian, Tang Rong and Wang Qi : School of Civil Engineering, Dalian University of Technology, Dalian 116085, P.R. China
Li Xin and Duan Yuping : School of Material and Engineering, Dalian University of Technology, Dalian 116085, P.R. China

Abstract
Holed-Incrementally Prestressed Concrete (H-IPC) girders are designed using the following new design concepts. At first, web openings reduce the self-weight of the girder, and also diffuse prestressing tendon anchorages. The reduced end anchoring forces decrease the web thickness of the end sections. Additionally, precast technology help to improve the quality of concrete and to reduce the construction period at the site. For experimentally verification, two 50 m full-scale H-IPC girders are manufactured with different concrete strength of 55 MPa and 80 MPa. The safety, stiffness, ductility, serviceability and crack development of H-IPC girder are measured and compared with each other for different strengths. Both girders show enough strength to carry live load and good stiffness to satisfy the design criteria. The experimental result shows the advantages of using high strength concrete and adopting precast girder. The test data can be used as a criterion for safety control and maintenance of the H-IPC girder.

Key Words
H-IPC; holed web; incrementally prestressed concrete girder; precast girder; opening

Address
Man Yop Han and Tae Heon Kang : Department of Civil Systems Engineering, Ajou University, Suwon 443-749, Korea
Sung Bo Kim : School of Civil Engineering, Chungbuk National University, Cheongju 361-763, Korea

Abstract
Steel fibre reinforced concrete (SFRC) is an anisotropic material due to the random orientation of the fibres within the cement matrix. Fibres under different inclination angles provide different strength contribution of a given crack width. For that the pull-out response of inclined fibres is of great importance to understand SFRC behaviour, particularly in the case of fibres with hooked ends, which are the most widely used. The paper focuses on the numerical modelling of the pull-out response of this kind of fibres from high-strength cementitious matrix in order to study the effects of different inclination angles of the fibres to the load-displacement pull-out curves. The pull-out of the fibres is studied by means of accurate three-dimensional finite element models, which take into account the nonlinearities that are present in the physical model, such as the nonlinear bonding between the fibre and the matrix in the early stages of the loading, the unilateral contact between the fibre and the matrix, the friction at the contact areas, the plastification of the steel fibre and the plastification and cracking of the cementitious matrix. The bonding properties of the fibre-matrix interface considered in the numerical model are based on experimental results of pull-out tests on straight fibres.

Key Words
hooked steel fibres; inclination angle; pull-out strength; high-strength cementitious matrix; three-dimensional finite element modelling

Address
Kyriaki Georgiadi-Stefanidi, Olympia Panagouliand Alexandra Kapatsina : Laboratory of Structural Analysis and Design, Department of Civil Engineering,University of Thessaly, Pedion Areos, 38334 Volos, Greece

Abstract
The evolution of nanotechnology provides materials with advance properties. It

Key Words
oxide nanoparticles; concrete; fresh concrete properties; hardened concrete properties

Address
Gholam Reza Khayati, Hojat Mirzaei Ghasabe and Masoud Karfarma: Department of Materials Science and Engineering, Shahid Bahonar University of Kerman, P.O. Box 76169133, Kerman, Iran



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