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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Computers and Concrete
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Volume & Issues
Volume 12, Issue 6 - Dec 2013
Volume 12, Issue 5 - Nov 2013
Volume 12, Issue 4 - Oct 2013
Volume 12, Issue 3 - Sep 2013
Volume 12, Issue 2 - Aug 2013
Volume 12, Issue 1 - Jul 2013
Volume 11, Issue 6 - Jun 2013
Volume 11, Issue 5 - May 2013
Volume 11, Issue 4 - Apr 2013
Volume 11, Issue 3 - Mar 2013
Volume 11, Issue 2 - Feb 2013
Volume 11, Issue 1 - Jan 2013
Selecting the target year
The anchorage-slip effect on direct displacement-based design of R/C bridge piers for limiting material strains
Mergos, P.E. ;
Computers and Concrete, volume 11, issue 6, 2013, Pages 493~513
DOI : 10.12989/cac.2013.11.6.493
Direct displacement-based design (DDBD) represents an innovative philosophy for seismic design of structures. When structural considerations are more critical, DDBD design should be carried on the basis of limiting material strains since structural damage is always strain related. In this case, the outcome of DDBD is strongly influenced by the displacement demand of the structural element for the target limit strains. Experimental studies have shown that anchorage slip may contribute significantly to the total displacement capacity of R/C column elements. However, in the previous studies, anchorage slip effect is either ignored or lumped into flexural deformations by applying the equivalent strain penetration length. In the light of the above, an attempt is made in this paper to include explicitly anchorage slip effect in DDBD of R/C column elements. For this purpose, a new computer program named RCCOLA-DBD is developed for the DDBD of single R/C elements for limiting material strains. By applying this program, more than 300 parametric designs are conducted to investigate the influence of anchorage slip effect as well as of numerous other parameters on the seismic design of R/C members according to this methodology.
Expanding the classic moment-curvature relation by a new perspective onto its axial strain
Petschke, T. ; Corres, H. ; Ezeberry, J.I. ; Perez, A. ; Recupero, A. ;
Computers and Concrete, volume 11, issue 6, 2013, Pages 515~529
DOI : 10.12989/cac.2013.11.6.515
The moment-curvature relation for simple bending is a well-studied subject and the classical moment-curvature diagram is commonly found in literature. The influence of axial forces has generally been considered as compression onto symmetrically reinforced cross-sections, thus strain at the reference fiber never has been an issue. However, when dealing with integral structures, which are usually statically indeterminate in different degrees, these concepts are not sufficient. Their horizontal elements are often completely restrained, which, under imposed deformations, leads to moderate compressive or tensile axial forces. The authors propose to analyze conventional beam cross-sections with moment-curvature diagrams considering asymmetrically reinforced cross-sections under combined influence of bending and moderate axial force. In addition a new diagram is introduced that expands the common moment-curvature relation onto the strain variation at the reference fiber. A parametric study presented in this article reveals the significant influence of selected cross-section parameters.
Mechanical properties of natural fiber-reinforced normal strength and high-fluidity concretes
Kim, Joo-Seok ; Lee, Hyoung-Ju ; Choi, Yeol ;
Computers and Concrete, volume 11, issue 6, 2013, Pages 531~539
DOI : 10.12989/cac.2013.11.6.531
An experimental investigation of mechanical properties of jute fiber-reinforced concrete (JFRC) has been reported for making a suitable construction material in terms of fiber reinforcement. Two jute fiber reinforced concretes, called jute fiber reinforced normal strength concrete (JFRNSC) and jute fiber-reinforced high-fluidity concrete (JFRHFC), were tested in compression, flexure and splitting tension. Compressive, flexural and splitting tensile strengths of specimens were investigated to four levels of jute fiber contents by volume fraction. From the test results, Jute fiber can be successfully used for normal strength concrete (NSC) and high-fluidity concrete (HFC). Particularly, HFC with jute fibers shows relatively higher improvement of strength property than that of normal strength concrete.
Evaluation of the different genetic algorithm parameters and operators for the finite element model updating problem
Erdogan, Yildirim Serhat ; Bakir, Pelin Gundes ;
Computers and Concrete, volume 11, issue 6, 2013, Pages 541~569
DOI : 10.12989/cac.2013.11.6.541
There is a wide variety of existing Genetic Algorithms (GA) operators and parameters in the literature. However, there is no unique technique that shows the best performance for different classes of optimization problems. Hence, the evaluation of these operators and parameters, which influence the effectiveness of the search process, must be carried out on a problem basis. This paper presents a comparison for the influence of GA operators and parameters on the performance of the damage identification problem using the finite element model updating method (FEMU). The damage is defined as reduction in bending rigidity of the finite elements of a reinforced concrete beam. A certain damage scenario is adopted and identified using different GA operators by minimizing the differences between experimental and analytical modal parameters. In this study, different selection, crossover and mutation operators are compared with each other based on the reliability, accuracy and efficiency criteria. The exploration and exploitation capabilities of different operators are evaluated. Also a comparison is carried out for the parallel and sequential GAs with different population sizes and the effect of the multiple use of some crossover operators is investigated. The results show that the roulettewheel selection technique together with real valued encoding gives the best results. It is also apparent that the Non-uniform Mutation as well as Parent Centric Normal Crossover can be confidently used in the damage identification problem. Nevertheless the parallel GAs increases both computation speed and the efficiency of the method.
Strength design criterion for asymmetrically reinforced RC circular cross-sections in bending
Hernandez-Montes, E. ; Alameda-Hernandez, P. ; Gil-Martin, L.M. ;
Computers and Concrete, volume 11, issue 6, 2013, Pages 571~585
DOI : 10.12989/cac.2013.11.6.571
Asymmetrical reinforcement for circular sections in wall piles is an efficient construction component with reduced embodied energy. It has been proven that asymmetrical reinforced wall piles may save more than 50% of the reinforcement than the traditional symmetrically reinforced circular sections. The use of this new type of structural member increases the number of variables in the design problem, which makes its use by engineers more complicated. In order to facilitate the use of the asymmetrically reinforced piles, this paper presents a criterion for the design of this type of structural member. The chosen criterion has been analyzed with the help of flexural capacity-cost curves. The new criterion is similar to the design procedure traditionally used for RC beams.
Predictive modeling of concrete compressive strength based on cement strength class
Papadakis, V.G. ; Demis, S. ;
Computers and Concrete, volume 11, issue 6, 2013, Pages 587~602
DOI : 10.12989/cac.2013.11.6.587
In the current study, a method for concrete compressive strength prediction (based on cement strength class), incorporated in a software package developed by the authors for the estimation of concrete service life under harmful environments, is presented and validated. Prediction of concrete compressive strength, prior to real experimentation, can be a very useful tool for a first mix screening. Given the fact that lower limitations in strength have been set in standards, to attain a minimum of service life, a strength approach is a necessity. Furthermore, considering the number of theoretical attempts on strength predictions so far, it can be seen that although they lack widespread accepted validity, certain empirical expressions are still widely used. The method elaborated in this study, it offers a simple and accurate, compressive strength estimation, in very good agreement with experimental results. A modified version of the Feret's formula is used, since it contains only one adjustable parameter, predicted by knowing the cement strength class. The approach presented in this study can be applied on any cement type, including active additions (fly ash, silica fume) and age.
Polynomial modeling of confined compressive strength and strain of circular concrete columns
Tsai, Hsing-Chih ;
Computers and Concrete, volume 11, issue 6, 2013, Pages 603~620
DOI : 10.12989/cac.2013.11.6.603
This paper improves genetic programming (GP) and weight genetic programming (WGP) and proposes soft-computing polynomials (SCP) for accurate prediction and visible polynomials. The proposed genetic programming system (GPS) comprises GP, WGP and SCP. To represent confined compressive strength and strain of circular concrete columns in meaningful representations, this paper conducts sensitivity analysis and applies pruning techniques. Analytical results demonstrate that all proposed models perform well in achieving good accuracy and visible formulas; notably, SCP can model problems in polynomial forms. Finally, concrete compressive strength and lateral steel ratio are identified as important to both confined compressive strength and strain of circular concrete columns. By using the suggested formulas, calculations are more accurate than those of analytical models. Moreover, a formula is applied for confined compressive strength based on current data and achieves accuracy comparable to that of neural networks.