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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Computers and Concrete
Journal Basic Information
Journal DOI :
Editor in Chief :
Chang-Koon Choi / Christian Meyer / Nenad Bi canic
Volume & Issues
Volume 16, Issue 6 - Dec 2015
Volume 16, Issue 5 - Nov 2015
Volume 16, Issue 4 - Oct 2015
Volume 16, Issue 3 - Sep 2015
Volume 16, Issue 2 - Aug 2015
Volume 16, Issue 1 - Jul 2015
Volume 15, Issue 6 - Jun 2015
Volume 15, Issue 5 - May 2015
Volume 15, Issue 4 - Apr 2015
Volume 15, Issue 3 - Mar 2015
Volume 15, Issue 2 - Feb 2015
Volume 15, Issue 1 - Jan 2015
Selecting the target year
Shear performance assessment of steel fiber reinforced-prestressed concrete members
Hwang, Jin-Ha ; Lee, Deuck Hang ; Park, Min Kook ; Choi, Seung-Ho ; Kim, Kang Su ; Pan, Zuanfeng ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 825~846
DOI : 10.12989/cac.2015.16.6.825
In this study, shear tests on steel fiber reinforced-prestressed concrete (SFR-PSC) members were conducted with test parameters of the concrete compressive strength, the volume fraction of steel fibers, and the level of effective prestress. The SFR-PSC members showed higher shear strengths and stiffness after diagonal cracking compared to the conventional prestressed concrete (PSC) members without steel fibers. In addition, their shear deformational behavior was measured using the image-based non-contact displacement measurement system, which was then compared to the results of nonlinear finite element analyses (NLFEA). In the NLFEA proposed in this study, a bi-axial tensile behavior model, which can reflect the tensile behavior of the steel fiber-reinforced concrete (SFRC) in a simple manner, was introduced into the smeared crack truss model. The NLFEA model proposed in this study provided a good estimation of shear behavior of the SFRPSC members, such as the stiffness, strengths, and failure modes, reflecting the effect of the key influential factors.
Modeling of damage in cement paste subject to external sulfate attack
Xiong, Chuansheng ; Jiang, Linhua ; Zhang, Yan ; Chu, Hongqiang ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 847~864
DOI : 10.12989/cac.2015.16.6.847
This study aimed to develop models of sulfate diffusion and ettringite content profile in cement paste for the predication of the damage behavior in cement paste subject to external sulfate. In the models, multiphase reaction equilibrium between ions in pore solution and solid calcium aluminates phases and the microstructure changes in different positions of cement paste were taken into account. The distributions of expansive volume strain and expansion stress in cement paste were calculated based on the ettringite content profile model. In addition, more sulfate diffusion tests and SEM analyses were determined to verify the reliability and veracity of the models. As the results shown, there was a good correlation between the numerical simulation results and experimental evidences. The results indicated that the water to cement ratio (w/c) had a significant influence on the diffusion of sulfate ions, ettringite concentration profile and expansion properties in cement paste specimens. The cracking points caused by ettringite growth in cement paste specimens were predicted through numerical methods. According to the simulation results, the fracture of cement paste would be accelerated when the specimens were prepared with higher w/c or when they were exposed to sulfate solution with higher concentration.
Modified electrical conductivity test method for evaluation concrete permeability
Pilvar, Amirreza ; Ramezanianpour, Ali Akbar ; Rajaie, Hosein ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 865~880
DOI : 10.12989/cac.2015.16.6.865
Standard test method for bulk electrical conductivity (ASTM C1760) provides a rapid indication of the concrete's resistance to the penetration of chloride ions by diffusion. In this paper a new approach for assessing the bulk electrical conductivity of saturated specimens of hardened concrete is presented. The test involves saturating concrete specimens with a 5 M NaCl solution before measuring the conductivity of the samples. By saturating specimens with a highly conductive solution, they showed virtually the same pore solution conductivity. Different concrete samples yield different conductivity primarily due to differences in their pore structure. The feasibility of the method has been demonstrated by testing different concrete mixtures consisting ordinary and blended cement of silica fume (SF) and calcined perlite powder (CPP). Two standard test methods of RCPT (ASTM C1202) and Bulk Conductivity (ASTM C1760) were also applied to all of the samples. The results show that for concretes containing SF and CPP, the proposed method is less sensitive towards the variations in the pore solution conductivity in comparison with RCPT and Bulk Conductivity tests. It seems that this method is suitable for the assessment of the performance and durability of different concretes containing supplementary cementitious materials.
Experimental crack analyses of concrete-like CSCBD specimens using a higher order DDM
Haeri, Hadi ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 881~896
DOI : 10.12989/cac.2015.16.6.881
A simultaneous analytical, experimental and numerical analysis of crack initiation, propagation and breaking process of the Central Straight through Crack Brazilian Disk (CSCBD) specimens under diametrical compression is carried out. Brazilian disc tests are being accomplished to evaluate the fracturing process based on stress intensity factors (SIFs). The effects of crack inclination angle and crack length on the fracturing processes have been investigated. The same experimental specimens have been numerically modeled by a higher order indirect boundary element method (HDDM). These numerical results are compared with the existing experimental results proving the accuracy and validity of the proposed numerical method.
Creep of concrete at variable stresses and heating
Klovanych, Sergei ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 897~908
DOI : 10.12989/cac.2015.16.6.897
This article gives analytical dependences for creep of concrete at heating, taking into account conditions of its drying. These dependences are based on the standard nonlinear theory of creep of concrete at a normal temperature and temperature-time analogy. For the description of creep at various stresses and temperatures the principle of superposition are used. All stages of model's creation are confirmed by the existing experimental data. Calculation examples are given.
Bond behavior of lightweight concretes containing coated pumice aggregate: hinged beam approach
Beycioglu, Ahmet ; Arslan, Mehmet E. ; Bideci, Ozlem S. ; Bideci, Alper ; Emiroglu, Mehmet ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 909~918
DOI : 10.12989/cac.2015.16.6.909
This paper presents an experimental study for determining the bond performance of lightweight concretes produced using pumice aggregate coated with colemanite-cement paste. For this purpose, eight hinged beam specimens were produced with four different concrete mixtures. 14 mm deformed bars with
development lengths were selected constant for all test specimens. All the specimens were tested in bending and load-slip values were measured experimentally to determine the effect of colemanite-cement coated pumice aggregate on bond performances of lightweight concretes. Test results showed that, colemanite-cement coated pumice aggregate increases compressive strength and bond performance of the lightweight concretes, considerably.
Non-destructive assessment of the three-point-bending strength of mortar beams using radial basis function neural networks
Alexandridis, Alex ; Stavrakas, Ilias ; Stergiopoulos, Charalampos ; Hloupis, George ; Ninos, Konstantinos ; Triantis, Dimos ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 919~932
DOI : 10.12989/cac.2015.16.6.919
This paper presents a new method for assessing the three-point-bending (3PB) strength of mortar beams in a non-destructive manner, based on neural network (NN) models. The models are based on the radial basis function (RBF) architecture and the fuzzy means algorithm is employed for training, in order to boost the prediction accuracy. Data for training the models were collected based on a series of experiments, where the cement mortar beams were subjected to various bending mechanical loads and the resulting pressure stimulated currents (PSCs) were recorded. The input variables to the NN models were then calculated by describing the PSC relaxation process through a generalization of Boltzmannn-Gibbs statistical physics, known as non-extensive statistical physics (NESP). The NN predictions were evaluated using k-fold cross-validation and new data that were kept independent from training; it can be seen that the proposed method can successfully form the basis of a non-destructive tool for assessing the bending strength. A comparison with a different NN architecture confirms the superiority of the proposed approach.
Application of a mesh-free method to modelling brittle fracture and fragmentation of a concrete column during projectile impact
Das, Raj ; Cleary, Paul W. ;
Computers and Concrete, volume 16, issue 6, 2015, Pages 933~961
DOI : 10.12989/cac.2015.16.6.933
Damage by high-speed impact fracture is a dominant mode of failure in several applications of concrete structures. Numerical modelling can play a crucial role in understanding and predicting complex fracture processes. The commonly used mesh-based Finite Element Method has difficulties in accurately modelling the high deformation and disintegration associated with fracture, as this often distorts the mesh. Even with careful re-meshing FEM often fails to handle extreme deformations and results in poor accuracy. Moreover, simulating the mechanism of fragmentation requires detachment of elements along their boundaries, and this needs a fine mesh to allow the natural propagation of damage/cracks. Smoothed Particle Hydrodynamics (SPH) is an alternative particle based (mesh-less) Lagrangian method that is particularly suitable for analysing fracture because of its capability to model large deformation and to track free surfaces generated due to fracturing. Here we demonstrate the capabilities of SPH for predicting brittle fracture by studying a slender concrete structure (column) under the impact of a high-speed projectile. To explore the effect of the projectile material behaviour on the fracture process, the projectile is assumed to be either perfectly-elastic or elastoplastic in two separate cases. The transient stress field and the resulting evolution of damage under impact are investigated. The nature of the collision and the constitutive behaviour are found to considerably affect the fracture process for the structure including the crack propagation rates, and the size and motion of the fragments. The progress of fracture is tracked by measuring the average damage level of the structure and the extent of energy dissipation, which depend strongly on the type of collision. The effect of fracture property (failure strain) of the concrete due to its various compositions is found to have a profound effect on the damage and fragmentation pattern of the structure.