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CONTENTS
Volume 17, Number 5, May 2016
 

Abstract
As concrete is most usable material in construction industry it

Key Words
concrete column; SWCNTs; DQM; buckling, foundation

Address
Ali Jafarian Arani and Reza Kolahchi: Department of Civil Engineering, Khomein Branch, Islamic Azad University, Khomein, Iran

Abstract
This paper describes a method of the refined plastic hinge approach in the framework of the higher-order element formulation that can efficaciously evaluate the limit state capacity of a whole reinforced concrete structural system using least number of element(s), whereas the traditional design of a reinforced concrete structure (i.e. AS3600; Eurocode 2) is member-based approach. Hence, in regard to the material nonlinearities, the efficient and economical cross-section analysis is provided to evaluate the element section capacity of non-uniform and arbitrary concrete section subjected to the interaction effects, which is helpful to formulate the refined plastic hinge method. In regard to the geometric nonlinearities, this paper relies on the higher-order element formulation with element load effect. Eventually, the load redistribution can be considered and make full use of the strength reserved owing to the redundancy of an indeterminate structure. And it is particularly true for the performance-based design of a structure under the extreme loads, while the uncertainty of the extreme load is great that the true behaviour of a whole structural system is important for the economical design approach, which is great superiority over the conservative optimal strength of an individual and isolated member based on traditional design (i.e. AS3600; Eurocode 2).

Key Words
refined plastic hinge method; second-order inelastic analysis; one element per member; higher-order element formulation; concrete structures; element load method

Address
C.K. IU: School of Civil Engineering and Built Environment,Queensland University of Technology, Brisbane, QLD, Australia


Abstract
The present work focuses on the use of coconut fiber in self compacting concrete. Self-Compacting Concrete (SCC) is a highly flowable, stable concrete which flows readily into place, filling formwork without any consolidation and without undergoing any significant segregation. Use of fibers in SCC bridge the cracks and enhance the performance of concrete by not allowing cracks to propagate. They contribute to an increased energy absorption compared to plain concrete. Coconut fiber has the highest toughness among all natural fibers. It is known that structures in the seismic prone areas are always under the influence of cyclic loading. To justify the importance of strengthening SCC beams with coir fiber, the present work has been undertaken. A comparison is made between cyclic and static loading of coconut fiber reinforced self compacting concrete (FRSCC) members. Using the test data obtained from the experiment, hysteresis loops were drawn and comparison of envelope curve, energy dissipation, stiffness degradation were made and important conclusions were draw to justify the use of coconut fiber in SCC.

Key Words
coconut fiber; self compacting concrete; flexural members; monotonic and cyclic loading

Address
Prasad M.L.V and Prasenjit saha: Department of Civil Engineering, NIT, Silchar -788010, Cachar District, Assam, India

P.R.Kumar: Department of Civil Engineering, National Institute of Technology, Warangal-506004, India

Abstract
In this study, the influence of coarse aggregate size and type on chloride penetration of concrete was investigated, and the grey correlation analysis was applied to find the key influencing factor. Furthermore, the proposed 6-10-1 artificial neural network (ANN) model was constructed, and performed under the MATLAB program. Training, testing and validation of the model stages were performed using 81 experiment data sets. The results show that the aggregate type has less effect on the concrete permeability, compared with the size effect. For concrete with a lower w/b, the coarse aggregate with a larger particle size should be chose, however, for concrete with a higher w/c, the aggregate with a grading of 5-20 mm is preferred, too large or too small aggregates are adverse to concrete chloride diffusivity. A new idea for the optimum selection of aggregate to prepare concrete with a low penetration is provided. Moreover, the ANN model predicted values are compared with actual test results, and the average relative error of prediction is found to be 5.62%. ANN procedure provides guidelines to select appropriate coarse aggregate for required chloride penetration of concrete and will reduce number of trial and error, save cost and time.

Key Words
coarse aggregate; permeability; concrete; grey correlation analysis; artificial neural network

Address
Lijuan Kong, Xiaoyu Chen and Yuanbo Du: School of Materials Science and Engineering, Shijiazhuang Tiedao University,
17 Northeast, Second Inner Ring, Shijiazhuang, P. R. China


Abstract
Optimization of the concrete mixture design is a process of search for a mixture for which the sum of the cost of the ingredients is the lowest, yet satisfying the required performance of concrete. In this study, a statistical model was carried out to model a cost effective optimal mix proportioning of high strength self-compacting concrete (HSSCC) using the Response Surface Methodology (RSM). The effect of five key mixture parameters such as water-binder ratio, cement content, fine aggregate percentage, fly ash content and superplasticizer content on the properties and performance of HSSCC like compressive strength, passing ability, segregation resistance and manufacturing cost were investigated. To demonstrate the responses of model in quadratic manner Central Composite Design (CCD) was chosen. The statistical model showed the adjusted correlation coefficient R2adj values were 92.55%, 93.49%, 92.33%, and 100% for each performance which establish the adequacy of the model. The optimum combination was determined to be 439.4 kg/m3 cement content, 35.5% W/B ratio, 50.0% fine aggregate, 49.85 kg/m3 fly ash, and 7.76 kg/m3 superplasticizer within the interest region using desirability function. Finally, it is concluded that multiobjective optimization method based on desirability function of the proposed response model offers an efficient approach regarding the HSSCC mixture optimization.

Key Words
central composite design; high strength self-compacting concrete; response surface method; optimization; desirability function

Address
Asaduzzaman Khan and Dookie Kim: Civil and Environmental Engineering, Kunsan National University,558 Daehak-ro, Gunsan-si 54150, Republic of Korea

Jeongyun Do: Industry-University Cooperation Foundation, Kunsan National University, 558 Daehak-ro, Gunsan-si 54150, Republic of Korea


Abstract
The present article discusses the effect of the ratio of bridge surface to total shear surface, number of bridge areas and normal stress on the failure behavior of the planar non-persistent open joints. Totally, 38 models were prepared using plaster and dimensions of 15 cm

Key Words
bridge area; jointed specimen; crack propagation; indirect shear loading; shear-fracture behavior

Address
Hadi Haeri: Department of Mining Engineering, Bafgh Branch, Islamic Azad University, Bafgh, Iran
Vahab Sarfarazi:Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran
Hossein Ali Lazemi: Department of Mining Engineering, Bafgh Branch, Islamic Azad University, Bafgh, Iran

Abstract
A predictive model for chloride binding isotherms of blended cements with various supplementary cementitious materials (SCMs) was established in this work. Totally 560 data points regarding the chloride binding isotherms of 106 various cements were collected from literature. The total amount of bound chloride for each mixture was expressed a combinational function of the predicted phase assemblage and binding isotherms of various hydrated phases. New quantitative expressions regarding the chloride binding isotherms of calcium-silicate-hydrate (C-S-H), AFm, and hydrotalcite phases were provided. New insights about the roles of SCMs on binding capabilities of ordinary portland cements (OPC) were discussed. The proposed model was verified using separate data from different sources and was shown to be reasonably accurate.

Key Words
cement; corrosion; degradation; computer-aided design & integration; reinforced concrete (RC)

Address
Hailong Ye, Xianyu Jin, Wei Chen, Chuanqing Fu and Nanguo Jin: College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, P.R. China

Abstract
In the standards, minimum reinforcement ratios are presented as the least reinforcement ratios that bearing elements should have in a way to include all systems and in general. However, naturally these general minimum ratios might be presented as being lower than the normally required reinforcement ratios by criteria such as system size, bearing system arrangement, section situation and distributions of the elements and earthquake effect. In this case, minimum reinforcement ratios may remain as meaningless restrictions. Then grouping the criterion that might affect reinforcement ratios according to certain parameters and creating minimum reinforcement ratios regarding preliminary design will provide ease and safety during the project designing. Moreover, it will enable fast and simple examinations in the beginning of project control and evaluation process. By means of the data which could be defined as

Key Words
finite element analysis, minimum reinforcement ratios, reinforced concrete, preliminary design

Address
Varol KOÇ and Yusuf EMİROGLU: Department of Civil Engineering, Ondokuz May


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