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CONTENTS
Volume 18, Number 2, August 2016
 

Abstract
This paper, proposes 20 models for predicting compressive strength of recycled aggregate concrete (RAC) containing silica fume by using gene expression programming (GEP). To construct the models, experimental data of 228 specimens produced from 61 different mixtures were collected from the literature. 80% of data sets were used in the training phase and the remained 20% in testing phase. Input variables were arranged in a format of seven input parameters including age of the specimen, cement content, water content, natural aggregates content, recycled aggregates content, silica fume content and amount of superplasticizer. The training and testing showed the models have good conformity with experimental results for predicting the compressive strength of recycled aggregate concrete containing silica fume.

Key Words
recycled aggregate concrete; silica fume; compressive strength; gene expression programming

Address
Gholamreza Abdollahzadeh: Department of Civil Engineering, Babol University of Technology, Babol, Iran

Ehsan Jahani: Department of Civil Engineering, University of Mazandaran, Babolsar, Iran

Zahra Kashir: Department of Technology, Tabari University of Babol, Babol, Iran

Abstract
The present work is concerned with a numerical investigation of the behaviour of reinforcedconcrete beams with non-bonded flexural tension reinforcement. The numerically-established behaviour of such beams with and without transverse reinforcement is compared with its counterpart of similar beams with bonded reinforcement. From the comparison, it is found that the development of bond anywhere within the shear span inevitably leads to inclined cracking which is the cause of

Key Words
beams; concrete-steel interaction; finite-element analysis; numerical testing; reinforced concrete; non-bonded reinforcement

Address
Gregoria M.Kotsovou: HeriotWatt University, Edinburgh, U.K.

Gerasimos M.Kotsovos: Lithos Consulting Engineers, Vari, Hellas

Abstract
The aim of this study is to investigate arrival direction effects of travelling waves on non-linear seismic response of arch dams. It is evident that the seismic waves may reach on the dam site from any direction. Therefore, this study considers the seismic waves arrive to the dam site with different angles,

Key Words
arch dams; nonlinear analysis; dam-water-foundation interaction; seismic travelling waves

Address
Mehmet Akköse: Department of Civil Engineering, Karadeniz Technical University, 61080, Trabzon, Turkey

Abstract
In this paper, a multilaminate based model have been developed and presented to predict the strain hardening behavior of rock. In this multilaminate model, the stress–strain behavior of a material is obtained by integrating the mechanical response of an infinite number of predefined oriented planes passing through a material point. Essential features such as the variable eformations hypothesis and multilaminate model are discussed. The methodology to be discussed here is modeling of strains on the 13 laminates passing through a point in each loading step. Upon the presented methodology, more attention has been given to hardening in non-linear behaviour of rock in going from the peak to residual strengths. The predictions of the derived stress–strain model are compared to experimental results for marble, sandstone and dense Cambria sand. The comparisons demonstrate the ability of this model to reproduce accurately the mechanical behavior of rocks.

Key Words
multilaminate model; variable deformations hypothesis; elasto-plastic behavior

Address
Hadi Haeri:Department of Mining Engineering, Bafgh Branch, Islamic Azad University, Bafgh, Iran

V. Sarfarazi: Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran

Abstract
Exterior beam-column joints are structural elements that ensure connection between beams and columns. The joint strength is generally assumed to be governed by the structural element of lowest load capacity (beam or column), however, the joint may be the weakest link. The joint shear behavior is still not well understood due to the influence of several variables, such as geometry of the connection, stress level in the column, concrete strength and longitudinal beam reinforcement. A parametrical study based only on experiments would be impracticable and not necessarily exposes the failure mechanisms. This paper reports on a set of numerical simulations conducted in DIANA

Key Words
beam-column; shear; numerical analysis; parametrical analysis; reinforced concrete

Address
Matheus F. A. Silva: 1University of Sao Paulo, Department of Structures, Av. Trabalhador Saocarlense, 400, 13566-590, Sao Carlos – SP, BRAZIL

Vladimir G. Haach: University of Sao Paulo, Department of Structures, Av. Trabalhador Saocarlense,400, 13566-590, Sao Carlos – SP, BRAZIL

Abstract
A rock mass containing non-persistent joints can only fail if the joints propagate and coalesce through an intact rock bridge. Shear strength of rock mass containing non-persistent joints is highly affected by the both, mechanical behavior and geometrical configuration of non-persistent joints located in a rock mass. Existence of rock joints and rock bridges are the most important factors complicating mechanical responses of a rock mass to stress loading. The joint-bridge interaction and bridge failure dominates mechanical behavior of jointed rock masses and the stability of rock excavations.The purpose of this review paper is to present techniques, progresses and the likely future development directions in experimental and numerical modelling of a non-persistent joint failure behaviour. Such investigation is essential to study the fundamental failures occurring in a rock bridge, for assessing anticipated and actual performances of the structures built on or in rock masses. This paper is divided into two sections. In the first part, experimental investigations have been represented followed by a summarized numerical modelling. Experimental results showed failure mechanism of a rock bridge under different loading conditions. Also effects of the number of non-persistent joints, angle between joint and a rock bridge, lengths of the rock bridge and the joint were investigated on the rock bridge failure behaviour. Numerical simulation results are used to validate experimental outputs.

Key Words
non-persistent joint; experimental test; numerical simulation

Address
Vahab Sarfarazi: Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran

Hadi Haeri: Department of Mining Engineering, Bafgh Branch, Islamic Azad University, Bafgh, Iran

Abstract
In order to observe the internal damage of concrete in real time, we introduced acoustic emission nondestructive detecting technology into a series of fracture tests; the test results revealed the whole process that concrete undergoes when it sustains damage that leads to failure, according to the change rules of the acoustic emission parameters. The results showed that both the initiation and unstable loads can be accurately determined using the abrupt change of the acoustic emission rate curves and the turning point of the acoustic emission parameters

Key Words
concrete; reinforced concrete; damage and fracture process; acoustic emission parameters;experimental study

Address
Fan Xiangqian,Hu Shaowei and Lu Jun: Department of Materials and Structural Engineering, Nanjing Hydraulic Research Institute, 210029, Nanjing, Jiangsu,China

Abstract
A new innovative composite material is textile reinforced cementitious composite (TRCC). To achieve high flexural performance researchers suggest polymermodification of TRCCmatrices. In this study, nine readymix repair mortars commonly used in construction industry and the production of TRCC elements were examined. Mechanical properties such as compressive and flexural strength, drying shrinkage were studied. Being a significant durability concern, alkali silica reaction tests were performed according to related standards. Results showed that, some ready repair mortar mixes are potentially reactive due to the alkali silica reaction. Two of the ready mortar mixes labelled as non-shrinkage in their technical data sheets showed the highest shrinkage. In this experiment,researchers designed new matrices. These matrices were fine grained concretes modified with polymer additives; latexes and redispersible powders. Two latexes and six redispersible powder polymers were used in the study. Mechanical properties of fine grained concretes such as compressive and flexural strengthswere determined.Results showed that some of the fine grained concretes cast with redispersible powders had higher flexural strength than ready mix repair mortars at 28 days. Matrix composition has to be designed for a suitable consistency for planned production processes ofTRCCandmechanical properties for load-carrying capacity.

Key Words
textile reinforced composite; durability; fine grained concrete; shrinkage; alkali silica reaction

Address
Esma Gizem Daskiran,Mehmet M. Daskiran and Mustafa Gencoglu: Department of Civil Engineering, Istanbul Technical University, Istanbul, TURKEY


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