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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of The Korean Society of Civil Engineers
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Journal DOI :
Korean Society of Civil Engeneers
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Volume & Issues
Volume 23, Issue 6D - Nov 2003
Volume 23, Issue 6C - Nov 2003
Volume 23, Issue 6B - Nov 2003
Volume 23, Issue 6A - Nov 2003
Volume 23, Issue 5D - Sep 2003
Volume 23, Issue 5C - Sep 2003
Volume 23, Issue 5B - Sep 2003
Volume 23, Issue 5A - Sep 2003
Volume 23, Issue 4D - Jul 2003
Volume 23, Issue 4C - Jul 2003
Volume 23, Issue 4B - Jul 2003
Volume 23, Issue 4A - Jul 2003
Volume 23, Issue 3D - May 2003
Volume 23, Issue 3C - May 2003
Volume 23, Issue 3B - May 2003
Volume 23, Issue 3A - May 2003
Volume 23, Issue 2D - Mar 2003
Volume 23, Issue 2C - Mar 2003
Volume 23, Issue 2B - Mar 2003
Volume 23, Issue 2A - Mar 2003
Volume 23, Issue 1D - Jan 2003
Volume 23, Issue 1C - Jan 2003
Volume 23, Issue 1B - Jan 2003
Volume 23, Issue 1A - Jan 2003
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A Study on the Dynamic Analysis of Buried Pipeline Subjected to Transverse Permanent Ground Deformation due to Liquefaction
Kim, Moon-Kyum ; Lim, Yun-Mook ; Kim, Tae-Wook ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 571~583
In this study, a general numerical algorithm was developed for the dynamic analysis of a buried pipeline that was subjected to transverse permanent ground deformation (PGD). PGD is caused by liquefaction, which can result in the structural damage of buried pipeline. It is defined as the large-scale volumetric deformation of ground, caused by the excess pore water pressure (PWP) generated during ground excitation. Since there is so close a relationship between the generation of excess PWP and the decrease of soil stiffness, the decreasing functional form of soil stiffness in time was used in this study. Through this approach, the effect of liquefaction-induced PGD was considered in a numerical algorithm. The entire system composed of pipeline and surrounding soil is numerically modeled using the theory of beam on elastic foundation and finite element method. Stiffness, damping, and mass-related terms were appropriately considered in the system equation of motion. Likewise, the
, method was used in performing time integration. To verify the developed algorithm, numerical results using the time history of Tokachi and East Chiba earthquakes were compared with the results of previous studies. In addition, relative influences of various parameters such as the characteristics of ground motion, the width of PGD, the coefficient of effective soil mass, and the decreasing function of soil stiffness were investigated.
Evaluation of Dapped Beam Design Methods using Strut-Tie Model Analysis
Yun, Young-Mook ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 585~597
Although dapped-end beams are widely used in bridge and building structures, accurate and reasonable design regulations on dapped-end beams are insufficient because of very complex ultimate behavior and stress distributions occurring at dapped ends. In this study, the validity of the suggested experimental and empirical design methods, conventional strut-tie models for dapped beam end, and nonlinear strut-tie model approach is evaluated through the strut-tie model analysies of four dapped-end beams tested to failure. According to the evaluation results, the nonlinear strut-tie model approach which takes the various characteristics of nonlinear behaviors into account in the analysis and design of concrete structures and predicts the strength of structural concrete by investigating the conditions for nodal zone strength, geometrical compatibility, and structural stability of a selected strut-tie model, proved to be an effective method for dapped-end beam design.
Behavior Properties of Concrete Slab Track Subjected to High-Speed Train Loads
Jo, Byung-Wan ; Tae, Ghi-Ho ; Ma, Soung-Wun ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 599~609
Finite element structural analysis are carried out to investigate the dynamic behavior of precast concrete slab track system based upon Singansun which is revolving around Japan and commonly adopted, and then checked deflection of rail and slab by finite-continuity elastic double beam theory. With an expected slab thickness and spring coefficient of rail-pad and slab supports for variables, vertical dynamic behavior of slab track are investigated. The result of analysis shows that the deflection and moment of rail is reduced as the increase of spring coefficient of rail-pad, and variation of slab behavior was very small. Vertical acceleration of slab is increased by increase of spring coefficient, thus to prevent vibration in sub-structure and destruction of track, it turns out to be efficient to reduce the spring coefficient of rail-pad. Design variable is width and height, and Constraint condition is stress and displacement of the slab track. From optimization result, width decreased but thickness expressed augmented value. The volume of structure modified slab track is decreased about 16% than existent Japan style slab track, and expressed small stress and displacement value of slab track.
A Study on the Ratio of Critical Stress-Resultant for Reduced Height of Bridge in a PSC Box Girder Bridge
Sim, Jae-Soo ; Park, Sang-Hyun ; Kim, Woo-Jong ; Jang, Hyun-Ock ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 611~618
The bridge construction which is made by prestressed concrete box girder started to study in Europe 1950s is a general process in terms of the stability, appearance and economical efficiency of the bridge. It is various to classify bridges used prestressed concrete box girder through the way of construction. Although the dead and constructible load except live loads act the structure, the structural system has large stresses at each section in comparison with a complete structure. Therefore this system for bridge structure is governed by under construction state because conditions such as support, curing and etc. are not completed. As a result of these reasons, the purpose of this research derives equations which relate the span-depth ratio to a critical moment developed an amount of prestressed strands, property, and the arrangement of strands at any section. In this manner, we can predict the external forces of structure and design the economical and slender section of bridge.
Flexural Fracture Toughness Characteristics of Hybrid Steel Fiber Reinforced Concrete
Kim, Nam-Wook ; Lee, Sang-Gui ; Han, Byung-Yong ; Bae, Ju-Seong ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 619~625
One of the main advantages of fiber reinforced concrete over plain concrete is the effect on increase of toughness. The exact measurement of toughness is very important in order to display the reinforcement effect produced by mixing fiber. This research examined the characteristics of flexural toughness and made a comparison between mono fiber reinforced concrete and hybrid fiber reinforced concrete using the widely used JSCE SF-4 and ASTM C-1018 toughness estimation methods of fiber reinforced concrete. The effects of differing fiber volume fraction (0%, 0.5%, 1.0%, and 1.5%) were studied. The test results of the hybrid reinforced concrete were compared with both plain and steel fiber reinforced concrete. From the results of this research, it was concluded that there was effect of increase toughness on the hybrid reinforced concrete compared to mono fiber reinforced concrete in flexural strength, flexural toughness using JSCE SF-4 and ASTM C-1018.
A Study on Proportion of Normal-Strength Self-Compacting Concrete Using Ground Calcium Carbonate
Choi, Yun-Wang ; Chung, Jee-Seung ; Moon, Dae-Joong ; Shin, Hwa-Cheol ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 627~637
In this paper, self-compacting concrete was manufactured using Ground Calcium Carbonate (GCC), which is produced at limestone mine in Danyang area. An experimental study on self-compacting concrete (SCC) was performed on flowability and compactability. The results of this study are as follows, when GCC was adequately mixed with 45% of ordinary portalnd cement, this concrete developed nomal strength about 30.6 MPa at the age of 28 days in the laboratory test. Self-compacting concrete mixed with GCC of 45% had to be secured on flowability and compactability so that the volume ratio of water-binder, fine aggregate and coarse aggregate were 97%, 46% and 50% respectively for satisfying the target value of slump flow, height difference of U-Box and drop time of Y-Lot. Furthermore, when Ground Glanulated Blast Furnace Slag and fly ash were mixed, the dosage of superplasticizer was reduced and the improving effect on flowability and compactability was indicated. Futhermore, 28 days compressive strength of SCC with Ground Glanulated Blast Furnace Slag and fly ash is satisfied the specified compressive strength of 24.5 MPa except for SCC with fly ash 30%. Namely, when GCC was contained for the self-compacting concrete for normal strength, it could informed that GCC will be able to utilized for the high value added material because that the unit weight cement content and the dosage of chemical admixtures were reduced.
Strength and Resistance of Chloride Ion Penetration of Repairing Material for Underwater Concrete Structure
Son, Young-Hyun ; Lim, Chi-Joong ; Kim, Se-Jun ; Park, Young-Suk ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 639~646
In this study, the performance evaluation for some repairing material like a ceramic-, epoxy-based material, and a cementitious material was experimentally performed. Application conditions and the mixing methods as well as materials were considered as experimental parameters. From the results of the compressive tests and the bond tests, it was shown that the strength development of the ceramic- and epoxy-based materials was nearly completed within 7 days but the compressive strength of cementitious material was gradually increased with age. And also, the ceramic-based material containing some coarse aggregate showed higher bond strength than that of all compared materials. From the durability examined by chloride-ion penetration test, it was found that the ceramic- and epoxy-based materials has nearly impermeable characteristics, but the anti-washout underwater concrete has very low resistance of chloride-ion penetration. These results may be attributed to the loss of cementitious binder and material segregation.
Transient Dynamic Behavior of Anti-symmetric Angle-ply Laminated Composite Plates using the Three-dimensional Higher-order Theory
Han, Sung-Cheon ; Chun, Kyoung-Sik ; Choi, Hoi-Kwon ; Chang, Suk-Yoon ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 647~655
To obtain more accurate response of laminated composite structures, the effect of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate need to be considered in the analysis. A three-dimensional higher-order theory, that requires no shear correction coefficients, is used to determine the transient dynamic response of laminated composite and sandwich plates. Solutions of simply-supported anti-symmetric angle-ply laminated composite plates and sandwiches are obtained in closed form using Navier's technique and the Newmark's direct integration technique is used for carrying out the integration of the equation of motion, to obtain the response history. Results are compared with those computed using the first order and the other higher order theories.
A 2-D Strain Energy Damage Detection Method Using Measured Data of No Original Analytical Model for Cable-Stayed Bridge
Heo, Gwang-Hee ; Lee, Giu ; Choi, Mhan-Young ; Lee, Dong-Gi ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 657~663
This paper presents a 2D strain energy damage detection method for cable-stayed bridges which effectively adapts experimental data without considering other analytical models. This detection method requires only mode vectors measured after and before damage is done, and many mode shapes are not necessary for this method. To prove the applicability of this detection method, a dynamic test was performed on the baseline structure constructed by mode vectors measured before any damage occurred, according to the rates and locations of damage. The strain energy derived from the baseline structure was compared to that of the damaged structure, and then such comparison produces damage index. At the same time, the test result was compared to the 2D strain energy method of other damage detection method such as eigenparameters method, MAC and COMAC method. All such comparisons prove the effectiveness of 2D strain energy damage detection method for Cable-stayed bridges, and also its potential effectiveness for real time monitoring.
Mechanical Properties of Structural Synthetic Fiber Reinforced Concrete and Shotcrete
Won, Jong-Pil ; Back, Chul-Woo ; Lee, Chang-Soo ; Park, Chan-Gi ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 665~671
Steel fiber is a widely used construction materials for better mechanical behavior of concrete structures than other fibers (polypropylene, glass, aramid). Also, steel fiber used in shortcrete and concrete are to improve toughness (post-crack energy absorption), impact and fatigue resistance, tensile strength and ductility. But structural synthetic fiber was developed in abroad and structural synthetic fiber can in lieu of was steel fiber for their advantage, no corrison, less weight etc. This study aims at evaluation of the properties of concrete and shotcrete using structural synthetic fiber. It was conducted with experiments of compressive strength test and flexural performance. According to laboratory test results, it was found that structural synthetic fiber reinforced concrete and shotcrete were significant improvement in the flexural toughness and flexural strength. Therefore, structural synthetic fiber helps were potential problems with the corrosion of steel fiber in concrete under severe exposure conditions. Structural synthetic fiber reinforced concrete presents a high performance construction materials suited for concrete and shotcrete application fields where environmental effects reduce the service life of structures and increase the life cycles costs.
3-D Frame Analysis and Design Using Refined Plastic Hinge Analysis Accounting for the Effect of Strain Reversal
Kim, Seung-Eock ; Kim, Chang-Sung ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 673~685
In this paper, the refined plastic-hinge analysis accounting for the effect of strain reversal caused by non-proportional loading is developed. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem, conventional refined plastic-hinge analyses have underestimated the strength of structures subjected to non-proportional loading, is overcome. Efficient ways of assessing steel frame behavior including gradual yielding associated with residual stresses and flexure, and second-order effect are presented. The modified stiffness degradation model approximating the effect of strain reversal is discussed in detail. The proposed analysis is verified by the comparison of the finite element analysis. A case study shows that the effect of strain reversal is a very crucial element to be considered in second-order plastic-hinge analysis. The proposed analysis is shown to be an efficient, reliable tool ready to be implemented into design practice.
A Study on Structural Behaviour at Rigid Connection of Rahmen-Type Hybrid Bridge
Kyung, Kab-Soo ; Lee, Hee-Hyun ; Jeon, Jun-Chang ; Cho, Kwang-Hyoun ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 687~694
In this study, structural behaviour at the rigid connection of a rahmen-type hybrid steel bridge which does not have shoes at the piers, is investigated experimentally by using 1/5 scaled model in order to prove its applicability. From this study, it is found that the connection has enough ductility and its load-carrying-capacity exceeds that of the RC pier. Therefore, it is expected that such bridge would be applied widely in the field where cost, maintenance and earthquake-proof etc. are important.
Dynamic Characteristics of Stay Cables with Viscoelastic Damper I. Kelvin Model
Ahn, Sang-Sup ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 695~702
The dynamic characteristics of taut cable equipped with a concentrated viscoelastic damper are investigated by the analytical method. A solution of dynamic equilibrium equation of cable-damper system is obtained using the Laplace transformation, which enables us to obtain the single solution for the problem of continuous system with a concentrated force. Damper is simulated with Kelvin model which consists of dashpot and linear spring in parallel. Therefore the stiffness of damper can be considered. Frequency equation is a basic equation to solve for investigating the dynamic characteristics of cable-damper system and is established by considering the force equilibrium condition at the damper installation position. Frequency equation represents the transcendental complex equation. Therefore, it can not be solved exactly. Two types of solutions are presented. That is, they are an accurate asymptotic approximation of the damping ratio and a simple iterative solution for all complex eigenfrequencies. When comparing with previous researches, asymptotic solution shows the good coincidence in either trend of variation of additional damping ratio or critical values and iterative solution gives the satisfactory results up to the specified damper installation position and number of mode. Asymptotic solution contains the governing parameters regarding the dynamic characteristics of cable-damper system. Thus it can be easily used when designing and analyzing of cable-damper system in addition to its simple form. It can be found that the stiffness of damper gives a significant influence on the maximum additional damping ratio, optimal damping coefficient and clamping ratio while less important to the mode shapes of cable-damper system. Moreover it declines the performance of damper. Thus the stiffness of damper can not be ignored.
Moving-Grid Finite Element Analysis of Turbulent Flow for Evaluating Unsteady Aerodynamic Forces Acting on a Bridge
Jeong, Un-Yong ; Kwon, Soon-Duck ; Koh, Hyun-Moo ; Kang, Soo-Chang ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 703~709
In this paper, a finite element analysis of turbulent flow around oscillating structure is presented for predicting the flutter onset velocity of bridge sections without any wind tunnel test in realistic wind velocity range. To model the flow turbulence, the low-Reynolds number
model modified by Kato-Launder method is used. The Reynolds-average Navier-Stokes equations and
transport equations are derived in weak form by using the SUPG convection-stabilizing scheme. The moving boundaries of wind flow domain under oscillating rigid bodies are described by arbitrary Lagrangian Eulerian method. Finally, by applying the proposed method to the rectangular-shaped girder section, close-to-experiment results are acquired.
Coupling Method of Element-Free Galerkin Method and Boundary Element Method Using the Domain Decompostion Method
Lee, Sang-Ho ; Kim, Myoung-Won ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 711~719
In this study, a new coupling method of Element-free Galerkin Method (EFGM) and Boundary Element Method (BEM) using the domain decomposition algorithm is presented for solving solid problems. In the proposed method, the problem domain is decomposed into EFGM and BEM sub-dmains that are partially overlapped and each sub-domain is analyzed independently by iteration technique. Then the coefficient matrices of EFGM and BEM sub-domains do not need to be combined, as required in the conventional coupling methods and the formulations of EFGM and BEM can be adopted as base programs for coupling only computer codes. In addition, some numerical examples are studied to verify stability and efficiency of the proposed method, in which numerical performance of the method is compared with that of conventional methods.
Static and Fatigue Behavior of the Long Span Precast Decks
Chung, Chul-Hun ; Lee, Han-Joo ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 721~731
Recently, for the purpose of shortening of construction period and cutting labor costs, precast prestressed concrete slabs are widely used to a new bridge system with fewer steel girders. However, there is little experience on the design and construction of prestressed concrete (PSC) decks in Korea. As the number of main girders decreases, the span length of the slabs increases. Therefore, there is a need for establishing a reasonable design method for long span slabs exceeding 5 m. In this study, static and fatigue tests were performed on long span precast deck with two girders. H-beams were used to simulate boundary conditions properly in the longitudinal direction. Two major test variables considered were span length and thickness. The results showed that PSC decks, with a thickness smaller than the minimum value required by the code, possessed a relatively high load carrying capacity. Under the static loading condition, the decks, with a minimum thickness by code and a thickness reduced by 13%, showed the ultimate flexural strength higher than expected. In addition, it seems that the flexural failure modes were more significant than the punching shear failure modes. During the fatigue test, the deck showed linear behavior up to 2 millian cycles.
Estimation of Structural Dynamic Parameters Using Wavelet Transform
Park, Hyung-Ghee ; Park, Jong-Yeol ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 733~742
This study presents the effective method for estimating the structural dynamic parameters such as natural frequencies, modal damping values, and mode shapes by performing structural dynamic tests. The wavelet transform is applied to analyze the response signals of tests on time-scale plane using Morlet wavelet as a mother wavelet. The method is verified by numerical experiments for free vibration test of a 3-span continuous beam and forced vibration test of a frame structure subjected to sine sweep load. The numerical test data in verification job are considered in case of signals without noise and affected by noise of Gaussian distribution. It has shown that both results calculated by the proposed method and analytical solution are almost identical.
A Study on Dynamics Behavior of Laminated Composite Plates under Impact Dynamic Loading
Chun, Kyoung-Sik ; Choi, Hoi-Kwon ; Chang, Suk-Yoon ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 743~752
In the present paper, the higher-order shear deformation theory is used to study the impact response of Graphite/Epoxy laminated composite plates. The impact response of laminated composite plates by a metallic impactor is studied by means of the finite-element method. The modified Hertzian contact law incorporated with the Newton-Raphson method is used to calculate the contact force between the impactor and the laminated plates. The Newmark direct integration was adopted to perform time integration from step to step. The results obtained from the present investigation are found to compare well with those existing in the open literature. Numerical results are presented to study the effects of span to thickness ratio, stacking sequence, fiber angle and initial velocity of the impactor for laminated plate during impact were studied.
Exact Static Element Stiffness Matrices of Non-symmetric Thin-walled Curved Beams
Yun, Hee-Taek ; Kim, Nam-Il ; Kim, Moon-Young ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 753~764
An evaluation procedure of exact static stiffness matrices for curved beams with non-symmetric thin-walled cross section are rigorously presented for the static analysis. Higher order differential equations for a uniform curved beam element are first transformed into a set of the first order simultaneous ordinary differential equations by introducing 14 displacement parameters where displacement modes corresponding to zero eigenvalues are suitably taken into account. This numerical technique is then accomplished via a generalized linear eigenvalue problem with non-symmetric matrices. Next the displacement functions of displacement parameters are exactly calculated by determining general solutions of simultaneous non-homogeneous differential equations. Finally an exact stiffness matrix is evaluated using force-deformation relationships. In order to demonstrate the validity and effectiveness of this method, displacements and normal stresses of cantilever thin-walled curved beams subjected to tip loads are evaluated and compared with those by thin-walled curved beam elements as well as shell elements.
Analysis of RC Frame Structures Considering Construction Sequences and Shore System
Kwak, Hyo-Gyoung ; Kim, Jin-Kook ; Hong, Su-Mi ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 765~775
Unlike the analysis and design of a reinforced concrete (RC) frame structure, which are conducted on the basis of a completed structure without considering any change in the structural system, the construction of an RC frame structure accompanies the sequential changes in the structural system and causes the actual structural behaviors which represent remarkable differences from those calculated in the analysis procedure. Accordingly, to simulate the actual structural behavior and to predict the exact structural responses, a rigorous numerical analysis considering creep, shrinkage, and construction sequence must be conducted. Upon these considerations, a numerical model, which was introduced in the previous study, is used in this paper for the analysis of RC frame structures. Many correlation studies with the purpose of analyzing the time-dependent behavior of building structures are conducted. In advance, the influence of shoring systems on the structural behavior is reviewed, and the importance for the analysis of RC frame structures considering the construction sequence and shoring systems is emphasized.
Buckling of Longitudinally Profiled Steel Plates in Compression
Hwang, Won-Sup ; Lee, Jang-Kyu ; Park, Wan-Bae ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 777~784
This paper presents the estimations of buckling coefficients and an ultimate strength for a longitudinally profiled plate (LP plate). From the buckling analysis of the LP plate compressed in one direction, the buckling coefficients for the thickness ratio are obtained by Rayleigh-Ritz method. This paper also provides the technique of a finite element analysis considering the residual distributions of residual stresses and forces equilibrium in the LP plate. The strength behavior of the LP plate obtained from the analysis shows that the ultimate strength differs from the strength which is calculated from the current design code. Based on the results, this paper presents some new proposals about the strength evaluations of the LP plate.
Analysis of the Failure Behavior in Concrete under Multi-axial Compressive Loading
Bang, Choon-Seok ; Song, Ha-Won ; Byun, Kun-Joo ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 785~793
Since quasi-brittle materials like concrete show strain localization behavior accompanied by strain softening, a numerical drawback such as mesh sensitivity is appeared in the finite element analysis. In this study, a homogenized crack model which overcomes the drawback and considers rate discontinuity in the constitutive equation is proposed for modeling of cracking in concrete and its propagation in strain softening regime under compressive load. And a finite element analysis program is developed for the analysis of failure behavior of plain concrete under multi-axial compressive load by utilizing the model. The results from the numerical analysis show good agreement with experimental data. For concrete specimens under biaxial and triaxial confining pressure, it is shown that compressive failure behaviors of the concrete with softening behavior are well predicted by the finite element analysis utilizing the homogenized crack model.
Experiment on Flexural Behavior of Prestressed Concrete Beams with External Tendons Considering Tendon Profiles and Number of Deviators
Oh, Byung-Hwan ; Yoo, Sung-Won ; Cho, Yun-Ku ; Suh, Jeong-In ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 4A, 2003, Pages 795~804
Recently, the externally prestressed unbonded concrete structures are increasingly being built. The mechanical behavior of prestressed concrete beams with external unbonded tendon is different from that of normal bonded PSC beams in that the slip of tendons at deviators and the change of tendon eccentricity occurs as external loads are applied in external unbonded PSC beams. The purpose of the present paper is therefore to evaluate the flexural behavior by performing static flexural test according to tendon profile and amount of deviators. From experimental results, before flexural cracking, there was no difference between external members and bonded members. However, after cracking, yielding load of reinforcement, ultimate load, and tendon stress of external members was lower than that of bonded members. The number of cracks in external members was few and that in the members with deviator at maximum moment area was also few. At the deviator, reinforcement stress was constant, even if reinforcements yielded. It is attributed from that tendon could resist external load. But outside of deviator, if reinforcements yielded, the amount of reinforcement stress increased rapidly because tendon could not resist external load. This phenomenon means that the reinforcement is very important in external members. From the measurement of tendon slip, before yielding of reinforcement, the amount of tendon slip was trivial, but after yielding of reinforcement. the amount of tendon slip increased rapidly, and then it increased slowly. This paper will be efficiently used for the evaluation of PSC structures with external unbonded tendons.