Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
International Journal of Concrete Structures and Materials
Journal Basic Information
Journal DOI :
Korea Concrete Institute
Editor in Chief :
Volume & Issues
Volume 2, Issue 2 - Dec 2008
Volume 2, Issue 1 - Jun 2008
Selecting the target year
Effect of Fire Induced Spalling on the Response of Reinforced Concrete Beams
Kodur, V.K.R. ; Dwaikat, M.B. ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 71~81
DOI : 10.4334/IJCSM.2008.2.2.071
A macroscopic finite element model is applied to investigate the effect of fire induced spalling on the response of reinforced concrete (RC) beams. Spalling is accounted for in the model through pore pressure calculations in concrete. The principles of mechanics and thermodynamics are applied to compute the temperature induced pore pressure in the concrete structures as a function of fire exposure time. The computed pore pressure is checked against the temperature dependent tensile strength of concrete to determine the extent of spalling. Using the model, case studies are conducted to investigate the influence of concrete permeability, fire scenario and axial restraint on the fire induced spalling and also on the response of RC beams. Results from the analysis indicate that the fire induced spalling, fire scenario, and axial restraint have significant influence on the fire response of RC beams. It is also shown that concrete permeability has substantial effect on the fire induced spalling and thus on the fire response of concrete beams. The fire resistance of high strength concrete beams can be lower that that of normal strength concrete beams due to fire induced spalling resulting from low permeability in high strength concrete.
Effect of Surface Finishing Materials on the Moisture Conditions in Concrete: Vapor and Water Permeability of Finishing Materials Under Changing Environmental Conditions
Ryu, Dong-Woo ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 83~90
DOI : 10.4334/IJCSM.2008.2.2.083
Permeability to vapor and water among other performances required for finishing materials is dealt with in this study. The relative moisture content of concrete coated/covered with a finishing material was experimentally investigated while changing the environmental conditions including temperature, relative humidity, and rainfall. An organic paint (water-based urethane), organic synthetic resin emulsion-type film coating (film coating E), and inorganic porcelain tiles were selected as the finishing materials. When compared from the aspect of vapor and water permeability, the vapor permeability and water permeability of water-based urethane were high and low, respectively; those of film coating E were high and high, respectively; and those of porcelain tiles were low and low, respectively. This means that the moisture state of concrete structures is governed not only by the environmental conditions but also by the performance of finishing materials. It is therefore of paramount importance to appropriately select a finishing material to address the specific deteriorative factors involved in the concrete structure to be finished.
Long-Term Monitoring and Analysis of a Curved Concrete Box-Girder Bridge
Lee, Sung-Chil ; Feng, Maria Q. ; Hong, Seok-Hee ; Chung, Young-Soo ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 91~98
DOI : 10.4334/IJCSM.2008.2.2.091
Curved bridges are important components of a highway transportation network for connecting local roads and highways, but very few data have been collected in terms of their field performance. This paper presents two-years monitoring and system identification results of a curved concrete box-girder bridge, the West St. On-Ramp, under ambient traffic excitations. The authors permanently installed accelerometers on the bridge from the beginning of the bridge life. From the ambient vibration data sets collected over the two years, the element stiffness correction factors for the columns, the girder, and boundary springs were identified using the back-propagation neural network. The results showed that the element stiffness values were nearly 10% different from the initial design values. It was also observed that the traffic conditions heavily influence the dynamic characteristics of this curved bridge. Furthermore, a probability distribution model of the element stiffness was established for long-term monitoring and analysis of the bridge stiffness change.
Corrosion Evaluation of Epoxy-Coated Bars by Electrochemical Impedance Spectroscopy
Choi, Oan-Chul ; Park, Young-Su ; Ryu, Hyung-Yun ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 99~105
DOI : 10.4334/IJCSM.2008.2.2.099
Southern exposure test specimens were used to evaluate corrosion performance of epoxy-coated reinforcing bars in chloride contaminated concrete by electrochemical impedance spectroscopy method. The test specimens with conventional bars, epoxy-coated bars and corrosion inhibitors were subjected 48 weekly cycles of ponding with sodium chloride solution and drying. The polarization resistance obtained from the Nyquist plot was the key parameter to characterize the degree of reinforcement corrosion. The impedance spectra of specimens with epoxy-coated bars are mainly governed by the arc of the interfacial film and the resistance against the charge transfer through the coating is an order of magnitude higher than that of the reference steel bars. Test results show good performance of epoxy-coated bars, although the coatings had holes simulating partial damage, and the effectiveness of corrosion-inhibiting additives. The corrosion rate obtained from the impedance spectroscopy method is equivalent to those determined by the linear polarization method for estimating the rate of corrosion of reinforcing steel in concrete structures.
Economic and Fast-track Rehabilitation of Concrete Pavements and Bridge Decks
Ramseyer, Chris ; Chancellor, Brent ; Kang, Thomas H.K. ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 107~113
DOI : 10.4334/IJCSM.2008.2.2.107
The last 10 years have seen considerable growth in the use of proprietary and special repair cements for concrete pavements in the state of Oklahoma. Many of these products lend themselves to "fast track" construction techniques that allow reopening to traffic within 12 hours or less. These products achieve high early strengths by accelerating the Portland cement hydration process for both Type I and Type III cements. In this paper, the important features of a durable repair which include strength, compatibility and bond or adhesion are first discussed. Then the development, testing and field implementation of the aforementioned materials are discussed including the learning curve required to implement a repair system, not just install a new material. Some of the materials discussed, while expensive on a cost per unit basis, hold great promise for economical use on fast track project.
On the Ductility of High-Strength Concrete Beams
Jang, Il-Young ; Park, Hoon-Gyu ; Kim, Sung-Soo ; Kim, Jong-Hoe ; Kim, Yong-Gon ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 115~122
DOI : 10.4334/IJCSM.2008.2.2.115
Ductility is important in the design of reinforced concrete structures. In seismic design of reinforced concrete members, it is necessary to allow for relatively large ductility so that the seismic energy is absorbed to avoid shear failure or significant degradation of strength even after yielding of reinforcing steels in the concrete member occurs. Therefore, prediction of the ductility should be as accurate as possible. The principal aim of this paper is to present the basic data for the ductility evaluation of reinforced high-strength concrete beams. Accordingly, 23 flexural tests were conducted on full-scale structural concrete beam specimens having concrete compressive strength of 40, 60, and 70MPa. The test results were then reviewed in terms of flexural capacity and ductility. The effect of concrete compressive strength, web reinforcement ratio, tension steel ratio, and shear span to beam depth ratio on ductility were investigated experimentally.
A Plastic-Damage Model for Lightweight Concrete and Normal Weight Concrete
Koh, C.G. ; Teng, M.Q. ; Wee, T.H. ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 123~136
DOI : 10.4334/IJCSM.2008.2.2.123
A new plastic-damage constitutive model applicable to lightweight concrete (LWC) and normal weight concrete (NWC) is proposed in this paper based on both continuum damage mechanics and plasticity theories. Two damage variables are used to represent tensile and compressive damage independently. The effective stress is computed in the Drucker-Prager multi-surface plasticity framework. The stress is then computed by multiplication of the damaged part and the effective part. The proposed model is coded as a user material subroutine and incorporated in a finite element analysis software. The constitutive integration algorithm is implemented by adopting the operator split involving elastic predictor, plastic corrector and damage corrector. The numerical study shows that the algorithm is efficient and robust in the finite element analysis. Experimental investigation is conducted to verify the proposed model involving both static and dynamic tests. The very good agreement between the numerical results and experimental results demonstrates the capability of the proposed model to capture the behaviors of LWC and NWC structures for static and impact loading.
Improving Durability Performance of Reinforced Concrete Structures with Probabilistic Analysis
Ferreira, Rui Miguel ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 137~143
DOI : 10.4334/IJCSM.2008.2.2.137
In recent years, much research work has been performed on durability design and long-term performance of concrete structures in marine environments. In particular, the development of new procedures for probability-based durability design has been shown to provide a more realistic basis for the analysis. This approach has been successfully applied to several new concrete structures, where requirements for a more controlled durability and service life have been specified. For reinforced concrete structures in a marine environment, it is commonly assumed that the dominant degradation mechanism is the corrosion of the reinforcement due to the presence of chlorides. The design approach is based on the verification of durability limit states, examples of which are: depassivation of reinforcement, cracking and spalling due to corrosion, and collapse due to cross section loss of reinforcement. With this design approach the probability of failure can be determined as a function of time. In the present paper, a probability-based durability performance analysis is used in order to demonstrate the importance of the durability design approach of concrete structures in marine environments. In addition, the sensitivity of the various durability parameters affecting and controlling the durability of concrete structures in a marine environment is studied. Results show that the potential of this approach to assist durability design decisions making process is great. Based the crucial information generated, it is possible to prolong the service life of structures while simultaneously optimizing the final design solution.
Flowability and Strength Properties of High Flowing Self-Compacting Concrete Using for Tunnel Lining
Choi, Yun-Wang ; Choi, Wook ; Kim, Byoung-Kwon ; Jung, Jea-Gwone ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 145~152
DOI : 10.4334/IJCSM.2008.2.2.145
So far, there has been no study of the concrete to strengthen in the lining of the tunnels, except for the study of the stability of subgrade and the tunnel construction technologies. In the existing concrete work for tunnel lining, lots of problems happen due to the partial compaction and the material segregation after casting concrete. Accordingly, the aim of this study is to improve economic efficiency and secure durability through the improvement of the construction performance and quality of the concrete for the tunnel lining among the civil structures. Therefore, the compactability and strength properties of the High Flowing Self-Compacting Lining Concrete (HSLC) are evaluated to develop the mixing proportion for design construction technology of HSLC that can overcome the inner cavity due to the reduced flowability and unfilled packing, which has been reported as the problem in the existing lining concrete. The result of the evaluation shows that the ternary mix meets the regulations better than the binary mix. Consequently, it has been judged applicable to the cement for tunnel lining.
Numerical Fracture analysis of prestressed concrete beams
Rabczuk, Timon ; Zi, Goangseup ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 153~160
DOI : 10.4334/IJCSM.2008.2.2.153
Fracture of prestressed concrete beams is studied with a novel and robust three-dimensional meshfree method. The meshfree method describes the crack as a set of cohesive crack segments and avoids the representation of the crack surface. It is ideally suited for a large number of cracks. The crack is modeled by splitting particles into two particles on opposite sides of the crack segment and the shape functions of neighboring particles are modified in a way the discontinuous displacement field is captured appropriately. A simple, robust and efficient way to determine, on which side adjacent particles of the corresponding crack segment lies, is proposed. We will show that the method does not show any "mesh" orientation bias and captures complicated failure patterns of experimental data well.
A Study on the Minimum Paste Volume in the Design of Concrete Mixture
Fowler, David W. ; Hahn, Michael De Moya ; Rached, Marc ; Choi, Doo-Sun ; Choi, Jae-Jin ;
International Journal of Concrete Structures and Materials, volume 2, issue 2, 2008, Pages 161~167
DOI : 10.4334/IJCSM.2008.2.2.161
Optimization of concrete mixing system is very important for the production of quality mixture of concrete and requires very complicated, specialized knowledge as there are a variety of variables that influence the result. One of the methods of optimizing the concrete mixing system is to minimize the volume of cement paste which, in turn, means maximizing the volume of aggregate. The purpose of this study is to determine the minimum volume of cement paste used in the design of concrete mixture and to design the optimum concrete mixing system based on the fluidity of mortar and concrete. In determining the minimum volume of cement paste, experiments of mortar and concrete were performed based on their workability, material segregation and bleeding. Type of aggregate, granularity distribution and sand percentage were used as test parameters and measurements were taken of the distribution of granularity, usage of HRWRA, minimum volume of paste and drying shrinkage and compressive strength of concrete.