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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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Korean Society of Civil Engeneers
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Volume & Issues
Volume 24, Issue 6D - Nov 2004
Volume 24, Issue 6C - Nov 2004
Volume 24, Issue 6B - Nov 2004
Volume 24, Issue 6A - Nov 2004
Volume 24, Issue 5D - Sep 2004
Volume 24, Issue 5C - Sep 2004
Volume 24, Issue 5B - Sep 2004
Volume 24, Issue 5A - Sep 2004
Volume 24, Issue 4D - Jul 2004
Volume 24, Issue 4C - Jul 2004
Volume 24, Issue 4B - Jul 2004
Volume 24, Issue 4A - Jul 2004
Volume 24, Issue 3D - May 2004
Volume 24, Issue 3C - May 2004
Volume 24, Issue 3B - May 2004
Volume 24, Issue 3A - May 2004
Volume 24, Issue 2D - Mar 2004
Volume 24, Issue 2C - Mar 2004
Volume 24, Issue 2B - Mar 2004
Volume 24, Issue 2A - Mar 2004
Volume 24, Issue 1D - Jan 2004
Volume 24, Issue 1C - Jan 2004
Volume 24, Issue 1B - Jan 2004
Volume 24, Issue 1A - Jan 2004
Selecting the target year
Path-dependant Nonlinear Analysis of Containment Reactor Vessel using Volume Control Method
Song, Ha-Won ; Lee, June-Hee ; Shim, Byul ; Byun, Keun-Joo ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 1~8
The so-called volume control method has overcome the drawbacks of load control method and displacement control method by adding a pressure node which has increment of pressure as an additional degree of freedom to a finite element. In this paper, a nonlinear volume control finite element method has been developed for the nonlinear analysis of reinforced concrete and prestressed concrete containment reactor vessels, which can predict the ultimate internal pressure capacity of a containment reactor vessel subjected to accidental internal pressure. Multi-layered shell element with the pressure node is adopted for the analysis by utilizing a path-dependant crack model, and an orthogonal two-way fixed crack model along with averaged in-plane 2D RC model and prestressing tendon model to for the layered shell elements. Reinforced concrete panel subjected to biaxial tension, reinforced concrete containment vessel and prestressed concrete containment vessel subjected to internal pressure are also analyzed. Both applicability and validity of the proposed method are shown by comparing the results of volume control method with both experimental results and existing analysis results.
Prediction of Non-linear Behavior for RC Beam Flexural Strengthened with CFRP Plate
Park, Jung-Yeol ; Cho, Hong-Dong ; Han, Sang-Hoon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 9~16
Carbon fiber reinforced polymer (CFRP) plates which have superior mechanical, chemical properties in comparison with conventional materials are used to strengthen reinforced concrete structures and related studies are actively performed. Especially, the studies on behavior prediction of RC beam strengthened with CFRP plate are performed recently. RC beams strengthened with CFRP plate appear material non-linearity, occurrence of cracks, geometric non-linearity, so prediction of behavior based on linear-elastic theory may differ from experimental results. Therefore, in this study, to predict the behavior of RC beam flexural strengthened with CFRP plate, analytical program considering material non-linearity is developed. To analyze, strain compatibility and force equilibrium are applied and internal forces of constitutive material are calculated using non-linear stress-strain relationship. To certainty the reliability of analytical program, deflection, strain of CFRP plate, change of neutral axis on cross section and crack distribution at failure are compared with those of experiment, and each results is almost coincident.
An Experimental Static Behavior of Steel.Concrete Composite Deck for Bridges
Jeong, Youn-Ju ; Jung, Kwang-Hoe ; Koo, Hyun-Bon ; Kim, Byung-Suk ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 17~25
This paper presents experimental static behavior of steel-concrete composite deck for bridge, which has studs to connect steel plate and concrete and T beam to improve structural performance, by steel plate shape, studs and load location. It proved that steel-concrete composite deck has a high structural performance and lightweight due to the efficient use of steel plate as a structural member, which has only used as form work. In failure mode, few specimen failed at punching shear and many specimens at concrete crushing, therefore proved it has sufficient stability to punching shear which is the most frequent damage of bridge deck. Steel-concrete composite deck of plane steel plate has a high structural performance, crack stability and interaction between steel plate and concrete, and that of corrugated steel plate has a high reduction of weight. However, as more studs installation, as more structural performance due to more interaction, but worse workability and cost. Composite deck with corrugated steel plate has reduced crack stability by deformation of steel plate and failed of welding between T-flange and steel plate. Therefore, in the near future, these disadvantages should be overcome.
Live Load Distribution PSC-Beam Bridges with Curved Slab
Kim, Jin-Ho ; Han, Kyung-Bong ; Park, Sun-Kyu ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 27~34
The current American Association of State Highway Transportation Officials (AASHTO) methods of wheel load distribution in bridges have been found to be unrealistic for at least some bridges. This Paper presents finite element analyses and modeling techniques of PSC-beam bridges with curved slab. A wheel load distribution formula is developed using the results of finite element analysis, which can be used to calculate the flexural stresses in PSC-beam bridges with curved slab. A typical bridge design was selected, and one parameter was allowed to vary within practical ranges while the remaining parameters were held constant. The parameters considered were the curvature of slab and span length, spacing of girder, spacing of cross beam, number of lanes. The proposed wheel load distribution formula give values that are generally much lower than the current American Association of State Highway Transportation Officials (AASHTO) values, but if the curvature of slab is bigger in PSC-beam bridges with curved slab, the proposed wheel load distribution formula give much higher values than American Association of State Highway Transportation Officials (AASHTO) values. This Paper will assist bridge engineers and researcher in modeling and predicting the actual wheel load distribution in PSC-beam bridges with curved slab.
Early-Age Behavior of Base Restrained RC Walls
Kwak, Hyo-Gyoung ; Ha, Soo-Jun ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 35~47
The early-age behavior of base restrained reinforced concrete (RC) walls is analyzed using a three-dimensional finite element method in this study. After calculating the temperature and internal relative humidity variations of an RC wall, determination of stresses due to thermal gradients, differential drying shrinkage, and average drying shrinkage is followed, and the relative contribution of these three stress components to the total stress is compared. The mechanical properties of early-age concrete, determined from many experimental studies, are taken into consideration and a discrete reinforcing steel derived using the equivalent nodal force concept is also used to simulate the cracking behavior of RC walls. In advance, to predict the crack spacing and maximum crack width in a base restrained RC wall, an analytical model which can simulate the post-cracking behavior of an RC tension member is introduced on the basis of the energy equilibrium before and after cracking of concrete. Finally, a design criterion to minimize the cracking in RC walls is recommended on the basis of the obtained numerical results.
A Study on Prediction of Ultimate Pressure Capacity for Prestressed Concrete Reactor Containment Structure
Song, Ha-Won ; Shim, Byul ; Byun, Keun-Joo ; Choi, Kang-Ryong ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 49~55
This paper studies experimentally and analytically the ultimate pressure capacity of a prestressed concrete reactor containment vessel (PCCV) subjected to internal pressure due to accident. Experimental data obtained from limit state test and structural failure mechanism test by internal pressure for a 1/4 scale PCCV model is analysed using the finite element analysis and the modeling of the analytical technique is verified. For the prediction of ultimate failure behavior, the dome and wall of the PCCV is modelled by multi-layered shell elements and plasticity and smeared crack model is adopted. It is shown that the PCCV has about 3 times greater safty margin than design values through the large-scale model test and the analysis, and radial displacement at midheight of the wall governs the ultimate behavior of the PCCV. For more accurate prediction of ultimate behavior of the PCCV, it is shown that the improvements in modelling for dome and unbonded tendon is necessary and it is also confirmed that tensile strength of concrete of the PCCV is one of the most important input data.
A Coupled Element-Free Galerkin and Infinite Element Method for Elastostatic Problems on Unbounded Domain
Lee, Sang-Ho ; Kim, Myoung-Won ; Kim, Tae-Yeon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 57~64
A new coupling algorithm that combines Element-Free Galerkin (EFG) method, one of meshfree methods, and Infinite Elements (IE) is developed in this study to solve the elastostatic problems with unbounded domain. Mapped infinite elements (mapped IE) and decay function infinite elements (decay IE) are coupled with the EFG method in the developed algorithm: In case of the mapped IE, a modified Jacobian matrix is used for the integration of unbounded domain whereas in decay IE, Gauss-Laguerre integration is used. The approximated displacement functions in the interface of EFG and IE regions are defined by using appropriate technique or well defined ramp function to preserve the continuity and linear consistency on the interface. Several benchmark problems are numerically examined to verify the effectiveness and accuracy of the developed algorithm. The numerical results show that the method works well for the elastic problems with infinite boundaries.
Adaptive Analysis with Mesh-free Method using the Double Projection method - I. Error Estimation -
Chung, Heung-Jin ; Lee, Gye-Hee ; Park, Heung-Soon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 65~71
A newly modified error estimation technique of double projection method for adaptive mesh-free analysis is proposed in this paper. Some oscillations of error distribution which is coming from projection technique which was our previous work, can be eliminated through double projection procedure of error distribution. The estimated error distribution without oscillation is more suitable for adaptive analysis. In double projection technique, additional projection of error distribution is based on integration points, so called virtual nodes. The averaging effect is maintained, as the domain of influence of double projection is bigger than that of projection method. Through various numerical experiments, the everaging effect is examined in terms of the size of domain of influence in double projection procedure, and it is found that the domain of influence should be large enough to cover the oscillation of original error distribution. The result of this study will be used in our next paper on adaptive procedure for mesh-free method.
Dynamic Analysis of Rectangular Liquid Storage Structures with Analytic Solution of Fluid Motion
Park, Jang-Ho ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 73~78
The analysis method is developed to analyze dynamic behavior of flexible rectangular liquid storage structures. Analytic solution for the irrotational motion of invicid and incompressible ideal fluid is presented. It is composed of the solution of the fluid motion due to ground motions in the rigid rectangular liquid storage structure and the solution of the fluid motion due to the structural motion in the flexible rectangular liquid storage structure. The motion of structure is modeled by finite elements. The analysis method is obtained by applying the analytic solution of the fluid motion to finite element equations of the structural motion. The fluid-structure interaction effect is reflected into the coupled equation of motion as added fluid mass matrix. The free surface sloshing motion and hydrodynamic pressure acting on the wall in the flexible rectangular liquid storage structure due to the horizontal ground motion are obtained by the developed method and verified.
Free Vibrations of Thick Plates with Concentrated Mass and Subjected to Inplane Force on Inhomogeneous Pasternak Foundation
Lee, Byoung-Koo ; Lee, Young-Soo ; Oh, Soog-Kyoung ; Lee, Tae-Eun ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 79~85
As the huge civil structures recently increase steeply, the sub-structures of them are often supported by the inhomogeneous foundations, which are subjected by many machines. Therefore the plates of sub-structures are affected by vibrations due to excited machines. The plates should be subjected to inplane forces caused by soil pressures. This paper deals with the free vibrations of thick plates, with a concentrated mass and subjected to inplane force, supported by inhomogeneous foundation. The inhomogeneous foundation is modeled by assigning the different values of Winkler foundation modulus to central and its outer regions of plate, respectively. The foundations are idealized as Pasternak foundation model which consists of both the Winkler foundation and the shear layer. Using this foundation model, the finite element methods are developed for calculating fundamental natural frequencies of such plates.
Optimum Design of Plane Steel Frames Using Second-Order Inelastic Analysis and a Genetic Algorithm
Yun, Young-Mook ; Kim, Byung-Hun ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 87~100
A GA-based optimum design algorithm incorporated with a second-order inelastic analysis method are presented. In the second-order inelastic analysis method, the geometric nonlinearity is considered by using the stability functions of beam-column members, and the material nonlinearity is considered by using the gradual stiffness degradation model that includes the effects of residual stresses, moment redistribution by the occurrence of plastic hinges, and geometric imperfections of members. In the genetic algorithm, tournament selection method and micro-GAs are employed. The objective function is expressed as the total weight of steel frames. The requirements of load-carrying capacity, serviceability, ductility, and construction workability are used as the constraint conditions. The appropriateness of the proposed method is verified by conducting the optimum design of several plane steel frames.
A Study on the Failure Mode of Long Span Decks
Chung, Chul-Hun ; Lee, Han-Joo ; Lee, Yong-Woo ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 101~106
Recently, the steel-concrete composite two-girders bridges, which have long span decks, have been regarded as one of economical as well as durable bridge types. However, for the design of long span deck a question is raised whether the current design provision is applicable in the respect of minimum thicknesses and bending moments. According to the current design code, as thickness of long span decks increases, fatigue shear carrying capacity of the decks increases. In this study, bridge decks, which have various spans, were designed to estimate boundary of fatigue failure modes and then shear-flexural fatigue relationship was studied using existing S-N curve. From the studies, failure mode for long span decks over about 7 m was flexural fatigue failure. Also, as the fatigue life of long span decks is effected the number of wheel loads as well as front and middle wheel loads, the effects must be considered in analyses and designs of long span decks.
New Suggestion of Minimum Cover Depth Considering Micro-Structures and Characteristics of Fluid Transport in Surface Concrete
Lee, Chang-Soo ; Yoon, In-Seok ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 107~113
This paper discussed micro-structure of surface concrete to understand transport properties from surface and to seek an intrinsic thickness from surface. The fluid transport properties and micro-structures of surface concrete were examined to acquire a long service life of concrete structures. The pore size distribution of concrete porosity using MIP method, water permeable porosity, rapid chloride penetration test, and ISA value using ISAT were accomplished. From the result of experiment, it was investigated that the micro-structure of concrete at the level of 20 mm from surface had a constant property. In order to acquire the long-term durability of concrete structures, it was determined the minimum cover depth should be over 20 mm. RCPT with thickness was accomplished to examine the effect ITZ on chloride penetration. Total passed charge was suddenly increased below 35 mm thickness. And at stress level higher than about to 70% of 28 days compressive strength, ionic penetration through cracks in the concrete sharply increased. In order to acquire the long-term durability of concrete structures under chloride-laden environment and service loading, it was concluded that the minimum cover depth should be over 35 mm.
Experimental Study on Prediction of Diffusion Behaviors of Chloride Ions for Concrete
Lee, Chang-Soo ; Yoon, In-Seok ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 115~124
The most common deteriorating processes of concrete structures in world wide is chloride ions. In order to analysis chloride into penetration into concrete, most useful method is to use Fick's End law. In this paper, modified Fick's 2nd law is suggested to consider time dependent surface chloride content and chloride diffusion coefficient with time and depth. The surface chloride content of blended concrete is highly accumulated in comparison with that of OPC concrete. And the surface chloride content of concrete under dry-wet cycles of salt water is highly accumulated in comparison with that of concrete under continuous immersion of salt water. In addition, surface chloride content of blended concrete is highly accumulated in comparison with that of concrete. The chloride diffusion coefficient of concrete was decreased with depth and time. Especially, the chloride diffusion coefficient binary and ternary blended concrete was significantly decreased relative to OPC concrete. From the relationship of free chloride contents and bound chloride contents, 0.03% divided a Langmuir isotherm from a Freundlich isotherm. In addition, chloride binding isotherms is suitable to Langmuir isotherm at low concentrations and a Freundlich isotherm at higher levels. From the result of prediction for chloride profiles, it was confirmed that ternary blended concrete was very suitable to marin environmental condition.
Dynamic Behavior of Composite Material Laminated Plates under Moving Loads
Chun, Kyoung-Sik ; Ji, Hyo-Seon ; Chang, Suk-Yoon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 125~134
In this paper, an analytical study is performed in order to investigate the characteristics of dynamic behavior of composite material laminated plates under moving loads. A formulation of a dynamic equilibrium equation of the laminated composite structures is presented. In the finite elements, modeling is established by the combined use of the addition of non-conforming displacement modes, assumed shear strain and improved shear stiffness. The mode superposition and Newmark direct integration method, adopted to perform time integration from step to step, are applied for dynamic analysis of Plates under moving load. Parametric studies for the effects of moving load, velocity, lamination scheme, stacking sequence, and fiber angle are carried out. The results in numerical analyses are compared with displacement, stress, influence surface, and dynamic magnification factor for laminated composite structures during moving load. It is found that the dynamic responses of the laminated plate are significantly varied by the effect of dynamic interaction between the moving velocities and the total stiffness of composite materials. The various results through numerical analysis are presented to use as a basic data in order to develop and grasp the behavior of all composite material bridges.
Smart Monitoring System for Large Structures Using Natural Excitation Techniques
Heo, Gwang-Hee ; Lee, Giu ; Lee, Chin-Ok ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 135~141
This paper aims to devise a smart system to maintain large structures against some randomly imposed external forces such as wind, earthquake and traffic load. This devised system first is set up to measure the ambient vibration of a structure occurring in normal traffic load and analyze its characteristics by the NExT combined with ERA. NExT is a technique which analyzes the dynamic characteristics of a structure by means of a time-domain algorithm on the basis of the response signals measured by cross correlation function. ERA also refers to a time-domain algorithm for the analysis of its dynamic characteristics, which is suitable specially for multiple input-output systems and for lightly damped structures. In order to prove the validity of this smart monitoring system with NExT and ERA, it was applied to a steel plate girder bridge which was currently in public use. Ambient vibration was measured by a form of cross power spectrum (CPS) from the thirty six accelerometers in total attached to the outer gilder which buttressed its upper slab. The obtained CPS was performed to inverse fast fourier transform (IFFT), and again into a form of impulse response function in time-domain, and those transformed data were made into an algorithm by MATLAB, which would finally be able to analyze the dynamic characteristics by ERA. This analysis was compared to the one which was made by FE results, and finally the comparison proved that the smart monitoring system using NExT and ERA is effective in maintaining a structure against randomly imposed external forces.
Analysis of Horizontal Reactions due to Moving Vehicle Load in Curved Bridges with Varied Support Conditions
Kim, Sang-Hyo ; Lee, Yong-Seon ; Cho, Kwang-Yil ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 143~150
A curved bridge can have two different support directions, which are in chord direction and tangent direction. This may bring the differences of load distribution due to the moving vehicles and global behavior of a curved bridge. In this study, 3-D numerical model is developed, which can demonstrate the static and dynamic responses of a curved bridge more precisely with the moving vehicles. The dynamic response induced by the centrifugal rolling motion of vehicle is identified according to the variations of the partial grade and the curvature of the slab. Dynamic characteristics of the curved bridge with the moving vehicle is analyzed under the condition of the support types and two different support systems. In general, while the vehicle is crossing the curved bridge, the negative reaction is occurred in the inside of the girder. The final result shows that the support system located outside the girder is more advantageous than other systems, and the characteristics of load distributions differ from the others in the various conditions of support systems.
Initiation and Propagation of Fatigue Cracks on Welded Details in Plate Girder
Lee, Myeong-Gu ; Kyung, Kab-Soo ; Lee, Seung-Yong ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 151~157
In order to investigate the characteristics for the initiation and propagation of fatigue cracks in large scale plate girder specimens, the fatigue tests were performed for four types of welded details used in steel bridges, such as in-plane gusset, out-of- plane gusset, cruciform, and cover plate. It was found that the fatigue crack initiates at the points of stress concentration which are the boundary between the base metal and the bead of weld in the part of the longitudinal edge of attachment, and propagates first along the boundary and along the perpendicular to the direction of the principle stress in the base metal of welded tip. In the parts where weld residual stress exists, the fatigue crack initiates and propagates even though the parts are under in compression.
Performance Evaluation of Repair System for the Underwater Structure using a Epoxy Fiber Panel
Park, Jun-Myung ; Hong, Sung-Nam ; Park, Sun-Kuy ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 159~166
An underwater structure is made to put with serious damage state by special environmental factor. If this damage phenomena persit, it is generated a structural serious problem because of the loss of the concrete section. It is very hard to repair the place where underwater structure was damaged because of environmental restriction condition. and quality control of a construction is too hard. Therefore, development of an effective repair method of underwater structure is requested. However, repair system of an underwater structure has never been studied so for. In this study, The repair work of an underwater structure damaged applied the method that used a fiber panel formwork. And an efficiency of structure repaired was evaluated.
Seismic Analysis of Reinforced Concrete Shear Wall
Kim, Tae-Hoon ; Park, Ji-Hong ; Choi, Kang-Ryong ; Shin, Hyun-Mock ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 167~175
The purpose of this study is to investigate the seismic behavior of reinforced concrete shear wall subjected to earthquake motions. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), was used for the analysis of reinforced concrete structures. A 4-node flat shell element with drilling rotational stiffness is used for spatial discretization. The layered approach is used to discretize behavior of concrete and reinforcement through the thickness. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. Solution of the equations of motion is obtained by numerical integration using Hither-Mushes-Taylor(HHT) algorithm. The proposed numerical method for the seismic analysis of reinforced concrete shear wall is verified by comparison of analysis results with reliable experimental results.
Determination of Optimal Sensor Location for Modal System Identification
Kwon, Soon-Jung ; Lim, Dong-Hwan ; Shin, Soo-Bong ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 177~183
In a structural inverse problem with a limited number of measuring degrees of freedom, the selection of OSL (optimal sensor locations) is critical for good identification results. The current research proposes a new OSL method for locating accelerometers for modal SI (system identification) and compares its results with those from an available OSL method. The proposed method applies the ML (maximum likelihood) method to determine OSL and results in a FIM (Fisher information matrix) based on the eigenvector sensitivity with respect to structural parameters. To consider real applications with no information on actual member properties, a statistical approach is proposed by assuming a certain error bound between the actual and the designed values. Simulation studies have been carried out to examine the proposed algorithm.
Reliability-based Failure Cause Assessment of Bridges Collapsed during Construction
Cho, Hyo-Nam ; Choi, Hyun-Ho ; Lee, Sang-Yoon ; Sun, Jong-Wan ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 185~195
Since many uncertainties are involved in structural failures or collapses, a probabilistic approach to failure cause assessment should be performed in order to consider the uncertainties. However, in most cases of forensic engineering, the failure cause assessments are performed by deterministic approaches though a great number of various uncertainties exist in the structural failures. Thus, a deterministic approach may have possibility for leading to unreasonable and unrealistic failure cause assessment due to ignorance of the uncertainties. Therefore, a probabilistic approach is needed to complement the shortcoming of deterministic approaches and to perform more reasonable and realistic failure cause assessment. In this study, reliability-based failure cause assessment (reliability-based forensic engineering) is performed, which can incorporate uncertainties in structural failures. For more practical applications, an automated ETA technique is proposed, which automatically generates defected structural models, performs structural analysis and reliability analysis, and calculates the failure probabilities of the failure events and the occurrence probabilities of failure scenarios. Also, for more precise reliability analysis, uncertainties are estimated more reasonably by using Bayesian approach based on the experimental laboratory testing data in forensic report.
Shear Buckling Strength of Trapezoidally Corrugated Steel Webs for Bridges
Gill, Heung-Bae ; Lee, Seung-Rok ; Lee, Hak-Eun ; Yoon, Tae-Yang ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 197~202
This paper deals with the shear buckling modes and strength of trapezoidally corrugated steel web, which is expected to be increasingly used at the web of hybrid girders and plate girders. Trapezoidally corrugated plates can buckle by three different shear buckling modes: local buckling (buckling of a panel), global buckling (buckling of a whole plate), and interactive buckling (buckling of several panels). Different buckling strength equations are provided for each buckling mode. The bifurcation buckling analysis using the finite element method has been performed in this study to analytically determine the buckling strength of trapezoidally corrugated webs and propose the buckling strength equations.
Consistent Assessment for Liquid Tightness of LNG Storage Tank Subjected to Cryogenic Temperature-induced Forces
Jeon, Se-Jin ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 203~210
In a design of LNG storage tank, one of the major leading conditions that significantly affect liquid tightness of the outer concrete wall is the cryogenic temperature of LNG under the emergency condition of LNG leakage from the inner steel tank. There are various code-related specifications that are based on the different approaches with regard to the liquid tightness design of liquid storage tanks. The specifications can be largely divided into three categories, that is, magnitude of the residual compressive stress, depth of the residual compression zone and crack width. Proposed in this study are the more consistent procedures to assess the liquid tightness of LNG tank which include above mentioned three categories taking the characteristics of the LNG tank into account. Structural behavior of cylindrical wall differs in hoop and vertical directions, so that the hoop tendons and vertical tendons are separately treated to ensure the liquid tightness in each direction. It is expected that the proposed schemes lead to a more effective serviceability design of LNG tanks which satisfies various requirements for the liquid tightness in an efficient manner.
Unified Robust Control System of Largescale Bridge for Effective Control - I. Performance Estimation of Control System Using Computer Simulation -
Heo, Gwang-Hee ; Lee, Dong-Gi ; Lee, Woo-Sang ; Lee, Giu ; Shin, Heung-Chul ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 211~218
The ultimate aims of this research are to design robust feedback control system which would contribute to more effective control of bridges, and to prove its validity by computer simulation and an experiment on reduced forms. This paper is particularly concerned with the evaluation of unified robust control system by a computer simulation as the first part of the whole project. A numerical example is applied to a bridge model of four-degree-of-freedom system which applied the EL Centro excitation as ground acceleration. The stability and performance of nominal system is investigated by applying the optimal output feedback controller designed by unified control system. The perturbed bound value, which is related to the stability of the system, was derived by an algorithm of the unified control system. In the real system which includes the perturbed bound value with nominal system, its robust stability and effectiveness were examined by an output feedback controller. Such a process was done by numerical simulation of computer control system in order to make the real control system equivalent to the constructed one. The simulation results show that the designed controller can be effective to solve the problem of performance degradation of the control system.
Distortional Analysis of Multicell Box Girders Using a Beam-Spring Element
Park, Nam-Hoi ; Kang, Young-Jong ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 219~224
In box girder structures, distortional warping and transverse bending normal stresses due to distortion of a cross section may consider as significant stresses unless distortion of the box section is appropriately restricted. In order to resist distortional stresses, design provisions of box girders give the installation of intermediate diaphragms in box girders. However, it can be considered as conservative design because spacing of intermediate diaphragms specifies uniformly 5m or 6m. In this study, a beam-spring element was developed in order to analyze distortion of multicell box girders with intermediate diaphragms. The present beam-spring element is composed of spring element for intermediate diaphragms and beam element for multicell box girders. Distortional analyses using the present beam-spring element were verified intensively from a series of distortional analyses using a three-dimensional shell element. From the comparative studies, accuracy of the present beam-spring element was shown to be excellent.
Fatigue Load Model For the Design of Steel Bridges
Bae, Doo-Byong ; Hwang, Eui-Seung ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 1A, 2004, Pages 225~232
This paper describes the procedures determining the fatigue load model for the design of highway bridges and suggests fatigue design truck. Efficient management of the bridges has become an increasing concern for those charged with maintaining highways and bridges. The volume and conditions of traffic with bridge type, geometry. configuration, and other factors, such as maintenance, determine the integrity and life expectancy of highway bridges and their components. Bridge weigh in motion (BWIM) system was selected and installed in a bridge on Kyungbu Highway to get the traffic data such as type of truck, axle distance and axle weight, etc. The BWIM system were successfully used to collect the data without stopping or slowing down the traffic. The data from BWIM system shows the wide range of axle weights and total weights which proves the effectiveness of the system. To evaluate the fatigue damage accumulation due to the traffic, normalized damage equation is derived. Two fatigue load models were proposed and fatigue load model 2, which was determined by utilizing heavier 21.1% of all truck data, shows close fatigue damage accumulation to the real fatigue damage curve for the span over 30m span.