Techno Press
Tp_Editing System.E (TES.E)
Login Search


cac
 
CONTENTS
Volume 10, Number 4, October 2012
 

Abstract
This paper describes the varying material model, the analysis method and the software development for reinforced concrete circular columns confined by spiral or hoop transverse steel reinforcement and subjected to eccentric loading. The widely used Mander model of concentric loading is adapted here to eccentric loading by developing an auto-adjustable stress-strain curve based on the eccentricity of the axial load or the size of the compression zone to generate more accurate interaction diagrams. The prediction of the ultimate unconfined capacity is straight forward. On the other hand, the prediction of the actual ultimate capacity of confined concrete columns requires specialized nonlinear analysis. This nonlinear procedure is programmed using C-Sharp to build efficient software that can be used for design, analysis, extreme event evaluation and forensic engineering. The software is equipped with an elegant graphics interface that assimilates input data, detail drawings, capacity diagrams and demand point mapping in a single sheet. Options for preliminary design, section and reinforcement selection are seamlessly integrated as well. Improvements to KDOT Bridge Design Manual using this software with reference to AASHTO LRFD are made.

Key Words
confined analysis; circular columns; eccentric loading; adjustable constitutive model; extreme events.

Address
Hayder A. Rasheed and Asad Esmaeily: Structural Engineering, Analysis and Mechanics Lab., Kansas State University, USA; Ahmed M. Abd El-Fattah: Dept. of Architecture, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia; John P. Jones and Kenneth F. Hurst: Bridge Design Office, Bureau of Design, Kansas Department of Transportation, USA

Abstract
In this paper, compressive strength, water permeability and abrasion resistance of concretes containing high volume fine fly ash (FFA) and fine ground palm oil fuel ash (GPA) were studied. Portland cement type I was replaced with FFA and GPA at dosages up to 70% by weight of binder. Ground river sand (GRS) was also used to replace Portland cement in order to indicate the level of filler effect. Results indicated that FFA was slightly more reactive than GPA. The replacement of 40-70% of FFA produced concretes with compressive strength, permeability and abrasion resistance comparable to those of normal concretes. The incorporation of GPA slightly reduced the performances of concretes as compared to those of FFA concretes. The reduction of Portland cement was partly compensated by the increase in pozzolanic activity of the fine fly ash and palm oil fuel ash and thus enabled the large replacement levels.

Key Words
concrete; water permeability; abrasion resistance; fly ash; palm oil fuel ash.

Address
S. Homwuttiwong: Department of Civil Engineering, Faculty of Engineering, Mahasarakham University, Mahasarakham 44150, Thailand; C. Jaturapitakkul: Department of Civil Engineering, Faculty of Engineering, King Mongkut

Abstract
Four Reinforced Concrete (RC) single span structural walls having various opening sizes and locations were constructed and tested under lateral reversed cyclic loading at the structural laboratory of Kyoto University. These specimens were scaled to 40% and represented the lower three stories of a sixstoried RC building. The main purposes of the experimental tests were to evaluate the shear behavior and to identify the influence of opening ratios on the cracks distribution and shear strength of RC structural walls. The shear strength of the specimens was estimated by combining the shear strength of structural wall without openings and the reduction factor that takes into account the openings. Experimental and analytical results showed that the shear strength was different depending on the loading direction due to opening locations. A two-dimensional finite element analysis was carried out to simulate the performance of the tested specimens. The constructed finite elements model simulated the lateral load-drift angle relations quite well.

Key Words
multi-story RC walls; eccentric openings; static test; shear behaviour; nonlinear FEM analysis.

Address
Rafik Taleb: National Center for Applied Research in Earthquake Engineering (CGS) Rue Kaddour RAHIM, BP 252, Hussein-Dey, Algiers, Algeria; Departement of Civil Engineering, Saad Dahleb Blida University, Blida, Algeria; Hakim Bechtoula: National Center for Applied Research in Earthquake Engineering (CGS) Rue Kaddour RAHIM, BP 252, Hussein-Dey, Algiers, Algeria; Masanubo Sakashita and Susumu Kono: Departement of Architecture and Architectural Engineering, Kyoto University, Nishikyo, Kyoto 6158540, Japan; Noureddine Bourahla: Departement of Civil Engineering, Saad Dahleb Blida University, Blida, Algeria

Abstract
In this paper, the mechanical strength of different lightweight mortars made with 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100 percentage of scoria instead of sand and 0.55 water-cement ratio and 350 kg/m3 cement content is investigated. The experimental result showed 7.9%, 16.7% and 49% decrease in compressive strength, tensile strength and mortar density, respectively, by using 100% scoria instead of sand in the mortar. The normalized compressive and tensile strength data are applied for artificial neural network (ANN) generation using generalized regression neural network (GRNN). Totally, 90 experimental data were selected randomly and applied to find the best network with minimum mean square error (MSE) and maximum correlation of determination. The created GRNN with 2 input layers, 2 output layers and a network spread of 0.1 had minimum MSE close to 0 and maximum correlation of determination close to 1.

Key Words
mechanical strength; scoria; ANN; GRNN; MSE.

Address
S.V. Razavi: Jundi-Shapur University of Technology, Dezful, Iran; M.Z. Jumaat: Civil Engineering Department, University Malaya(UM), Malaysia; E.S. Ahmed H: Civil Engineering Department, Universiti Kebangsaan Malaysia(UKM), Malaysia; Mohammadi, P.: Islamic Azad University, Dezful Branch, Iran

Abstract
Utilization of supplementary cementing materials (SCM) by the cement industry, as a highly promising solution of sustainable cement development aiming to reduce carbon dioxide emissions, necessitates a more thorough evaluation of these types of materials on concrete durability. In this study a comparative assessment of the effect of SCM on concrete durability, of every cement type as defined in the European Standard EN 197-1 is taking place, using a software tool, based on proven predictive models (according to performance-related methods for assessing durability) developed and wide-validated for the estimation of concrete service life when designing for durability under harsh environments. The effect of Type II additives (fly ash, silica fume) on CEM I type of cement, as well as the effect of every Portland-composite type of cement (and others) are evaluated in terms of their performance in carbonation and chloride exposure, for a service life of 50 years. The main aim is to portray a unified and comprehensive evaluation of the efficiency of SCM in order to create the basis for future consideration of more types of cement to enter the production line in industry.

Key Words
carbonation; cement type; chloride penetration; concrete technology; corrosion; model prediction; service life; software.

Address
S. Demis: AEIPLOUS Institute for Innovation & Sustainable Development, Patras, Greece; V.G. Papadakis: Department of Environmental and Natural Resources Management, University of Western Greece, Agrinio, Greece

Abstract
The quality of high performance concrete largely depends on water cement ratio, porosity, material composition and mix methods. The uniformity of color, texture and compressive strengths are quality indicators commonly used to assess the overall characteristics of concrete mixes. The homogeneity and share of coarse aggregates play a key role in concrete quality and must be analyzed in a microscopic point of view. This research studies the quality of high performance concrete by taking drilled cores in both horizontal and vertical directions from a 1.0 m3 specimen. The coarse aggregate, expressed in digitized 100x116 dpi resolution images are processed based on brightness in colors through commercial software converted into text files. With the image converting to text format, the share of coarse aggregate is quantified leading to a satisfactory assessment of homogeneity - a quality index of high performance concrete. The compressive strengths of concrete and the shares of coarse aggregate of the samples are also compared in this research study to illustrate its correlation in concrete quality. It is concluded that a higher homogeneity of aggregate exists in the vertical plane than that of the horizontal planes of the high performance concrete. In addition, the concrete specimen showing denser particle packing has relatively higher compressive strengths. The research methodology provides an easy-to-use, direct measurement of high performance concrete when conducting quality assessment in the construction site.

Key Words
image elements; high performance concrete; homogeneity; ANOVA.

Address
Sheng-Szu Peng and Edward H. Wang: Minghsin University of Science and Technology, Hsin-Chu, Taiwan; Her-Yung Wang and Yu-Te Chou: National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan

Abstract
This paper presents a finite element (FE) model for predicting the nonlinear response and behavior of a reinforced concrete T-beam deficient in shear under cyclic loading. Cracking loads, failure loads, response hysteresis envelopes and crack patterns were used as bench mark for comparison between experimental and FE results. A parametric study was carried out to predict the optimum combination of the open and close crack shear transfer coefficients (βt and βc) of the constitutive material model for concrete. It is concluded that when both shear transfer coefficients are equal to 0.2 the FE results gave the best correlation with the experimental results. The results were also verified on a rectangular shear deficient beam (R-beam) tested under cyclic loading and it is concluded that the variation of section geometry has no effect on the optimum choice of the values of shear transfer coefficients of 0.2. In addition, a parametric study based on the variation of concrete compressive strength, was carried out on the T-beam and it is observed that the variation of concrete compressive strength has little effect on the deflection. Further conclusions and observations were also drawn.

Key Words
reinforced concrete; finite element modeling; shear deficient T-beam; cyclic load.

Address
R.A. Hawileh and J.A. Abdalla: Department of Civil Engineering, American University of Sharjah, Sharjah, UAE; M.H. Tanarslan: Department of Civil Engineering, Dokuz Eylul University, Buca, Izmir 35160, Turkey


Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2017 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-42-828-7996, Fax : +82-42-828-7997, Email: info@techno-press.com