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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 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
Selecting the target year
An Application of Wheel-Running-Machine on Precast Concrete Decks Connected by Loop Joints
Kim, Yoon-Chil ; Park, Jong-Jin ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 807~814
Precast slabs connected by loop joints were subjected to the durability tests under repeated load. The tests were conducted with an application of wheel-running-machine. The test results indicated that the introduction of longitudinal prestress increased durability of the precast decks. The deterioration index of the longitudinally prestressed precast deck with an applied force twice the design load was 0.35 while the precast deck without longitudinal prestress was 0.4. Comparisons between the theoretical and experimental values of the displacement and strains of transverse rebars did not indicate significant reduction in both stiffness and durability after the completion of the tests.
Performance Evaluation of Concrete Using Corrosion Inhibitors
Bae, Su-Ho ; Chung, Young-Soo ; Ha, Jae-Dam ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 815~822
There are various corrosion protection measures for reinforcing steel in concrete, such as good-quality concrete, thick cover concrete, epoxy coated rebars, cathodic protection, the use of corrosion inhibitors as a concrete admixture, etc. Recently, corrosion inhibitors are known as one of most practical measures for the corrosion protection of reinforcing steel in concrete. Thus, the purpose of this experimental research is to evaluate the performance of corrosion inhibitors for normal and high strength concrete, and to propose a desirable measures for the corrosion control of reinforcing steel in concrete. For this purpose, test specimens in normal and high strength concrete were made with and without corrosion inhibitors. The accelerated corrosion test for reinforcing steel in concrete was adopted in accordance with JCI-SC3, which required the periodic 20 cycles for 140 days. One cycle includes 3 days for the wetting condition of
and 90% RH, and 4 days for the drying condition of
and 60% RH. It was observed from the test that corrosion inhibitors in normal and high strength concrete showed excellent corrosion resistance for reinforcing steel in concrete, but the effect of silica fume in high strength concrete without corrosion inhibitor on the corrosion protection of reinforcing steel was found to be negligible.
Active Control of MDOF Structures Using Independent Modal-Space Fuzzy Control Techniques
Park, Kwan-Soon ; Koh, Hyun-Moo ; Seo, Chung-Won ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 823~830
Independent modal space fuzzy control (IMSFC) method is studied for the active control of earthquake-excited structures. The proposed IMSFC method can achieve enhanced performance by real-time tuning of the feedback gains according to the modal responses of the structure. The state-space equations in physical coordinates are transformed into modal coordinates, and then optimal control theories are applied to obtain the each modal feedback gain. And rule-based fuzzy tuning is introduced in order to effectively modulate the modal gains with respect to the modal contributions to the response. For input information to the fuzzy inference engine, we use modal displacement and velocity responses. As an example to demonstrate the proposed approach, controller design and numerical simulation considering first few modes of six-degree-of-freedom building structure excited by El Centre (194) and Kobe (1995) earthquake are performed. From the comparative results with the other conventional methods, the IMSFC shows the enhanced performance for vibration control of earthquake-excited structures.
Investigation of the Shelter Effect of Porous Wind Fence Using Computational Fluid Dynamics
Jeong, Un-Yong ; Park, Tae-Kyu ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 831~839
In this paper, numerical analyses are performed to visualize the shelter effects of porous wind fence and to estimate the wind forces acting on it, and the estimated results are compared with the experimental ones. Throughout the analysis, the numerical results of the wind velocity and the wind force coefficients are shown to be more linearly related to the porosity of fence compared with the experimental ones. Finally, the regressed equations for each results are presented to utilize the proposed results in wind fence design.
Nonlinear Inelastic Optimal Design Using Genetic Algorithm
Kim, Seung-Eock ; Ma, Sang-Soo ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 841~850
An optimal design method in cooperated with nonlinear inelastic analysis method is presented. The proposed nonlinear inelastic method overcomes the difficulties due to incompatibility between the elastic global analysis and the limit state member design in the conventional LRFD method. The genetic algorithm uses a procedure based on Darwinian notions of survival of the fittest, where selection, crossover, and mutation operators are used among sections in the database to look for high performance ones. They satisfy the constraint functions and give the lightest weight to the structure. The objective function is set to the total weight of the steel structure and the constraint functions are load-carrying capacities, serviceability, and ductility requirement. Case studies of a three-dimensional frame and a three-dimensional steel arch bridge are presented.
A Study on the Minimum Thickness of Long Span Decks
Lee, Han-Joo ; Lee, Yong-Woo ; Chung, Chul-Hun ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 851~857
Recently, the steel-concrete composite two-girders bridges, which have PSC long span decks, have been regarded as one of the economical as well as durable bridge types. Usually, prestressing forces are introduced in the transverse direction of the long span deck. 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. In this study, 3-D finite element analyses were performed to compare actually required thickness of the long span deck with the code-specified minimum thickness. Also, full-scale static tests were conducted to examine the ultimate and serviceability behaviors of long span decks for the several thicknesses and spans. From the analytical and the experimental studies, it is concluded that the code-specified minimum thicknesses can be reduced at least for the long span decks. Finally, the effects of front and middle wheel loads or the deck behavior were investigated, which could induce unsafe characteristics especially for the long span decks over 10m.
Crack Control of Negative Moment Regions in Continuous Composite Box-Girder Bridges with Precast Decks by External Prestress
Ryu, Hyung-Keun ; Kim, Hyun-Sung ; Shim, Chang-Su ; Chang, Sung-Pil ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 859~867
In a continuous composite bridge with precast decks, tensile stress in a maximum negative moment region under service loads should be controlled. For ensuring the crack prevention at transverse joints, prestressing by internal tendons in all spans is not efficient. A stress distribution of concrete slab by internal tendons is complex due to several construction steps, shear pockets and prestress losses by long-term behavior. Therefore in the negative moment regions, additional prestressing method after shear connection is needed. In this paper, static tests on a two span continuous composite bridge with precast deck, which was prestressed additionally by external tendons near an interior support, were conducted and effects of the prestressing by external tendons were observed. Through analyses for a designed continuous composite bridge, applicable prestressing method for composite bridges with precast decks was proposed.
Analytical Study on Time-Dependent Behavior of Prestressed Concrete Structures
Kim, Tae-Hoon ; Choi, Jung-Ho ; Choi, Kang-Ryong ; Shin, Hyun-Mock ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 869~875
The purpose of this study is to investigate the time-dependent behavior of prestressed concrete structures. The accuracy and objectivity of the assessment process may be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of concrete structures was used. The material nonlinearities are taken into account by comprising the tension, compression, and shear models of cracked concrete and models for reinforcements and tendons in the concrete. The smeared crack approach is incorporated. It accounts for the aging, creep and shrinkage of concrete and the stress relaxation of prestressed steel. The proposed numerical method for time-dependent behavior of prestressed concrete structures is verified by comparison with reliable experimental results.
Nonlinear Analysis of Concrete Filled Steel Tube Subjected to Pure Bending
Chung, Chul-Hun ; Jin, Byeong-Moo ; Kim, In-Gyu ; Park, Se-Jin ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 877~887
In this study, nonlinear behavior of concrete filled circular steel tube has been investigated. Also the nonlinear behavior of bare steel tube has been analyzed and compared to that of the concrete filled steel tube. The potential imperfection in steel has been considered as the buckling modes of circular steel tube subjected to pure bending. The initial imperfection has turned out to be one of the important factors to the ultimate load. It was certified that the concrete filled effect increased the ultimate loads of concrete filled tube with an initial imperfection. A simple concrete-filled modeling which reflects the fact that the deformation of cross-section of steel tube is constrained by the in-filled concrete was used for this study. The numerical analysis results show that the concrete-filled effects result in the increase of the ultimate load and the ductility of the bending member. From the results of some examples concerned with the thickness of steel tube, it is concluded that the concrete filled effect is apparent for the thinner steel tube.
Point Collocation Meshfree Method Based on Derivatives Approximation for Linear Elasticity
Lee, Sang-Ho ; Kim, Hyo-Jin ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 889~899
A program which analyzes solid problems by using point collocation meshfree method based on the fast derivatives approximation of shape function is developed in this study. Meshfree approximation with approximated derivative of shape function is reviewed, and formulation of linear elastic solid mechanics by point collocation method is presented. It implies that governing equation of solid mechanics with strong form is directly discretized without numerical integration cells or grid. Because the regularity of weight function is not required due to a use of approximated derivative, we can expand the choice of weight function. Here we propose exponential type weight function that does not require differentiability. The convergence and stability of point collocation meshfree method based on derivatives approximation is verified by passing the generalized patch test. Also, the efficiency and applicability of the method in solid mechanics is verified by solving types of solid problems under various essential and natural boundary condition. Numerical results show that not only the derivatives approximation enables to compute the derivatives of shape function very fast and accurately enough to replace the classical direct derivative calculation, but also a use of the proposed weight function leads lower error and higher convergence rate than that of the conventional weight functions.
Comparative Study on Static, Buckling and Free Vibration Analysis of Laminated Composite Plates using Various Serendipity Finite Elements
Chun, Kyoung-Sik ; Choi, Hoi-Kwon ; Chang, Suk-Yoon ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 901~909
A formulation of an isoparametric quadrilateral eight-node serendipity elements are presented and employed in the static, buckling and free-vibration analysis of laminated composite plates including transverse shear deformations. The elements are based on inplane displacement models which incorporate first-order to higher-order terms in thickness coordinate for the consideration of transverse shear deformations. The eight-node 56-d.o.f (8QUAD56) and 72-d.o.f (8QUAD72) considered higher-order in-plane displacement models and the transverse deflection across plate thickness is assumed constant. While in the eight-node 88-d.o.f (8QUAD88) and 96-d.o.f (8QUAD96), the transverse deflection varies in the form of a second and third order power series expansion of thickness coordinate. In this paper, parameter studies are carried out for static, buckling and free vibration analysis by geometrical shape variations; such as change of side-to-thickness ratio and also by laminated composite; such as fiber orientation, stacking sequence, elasticity ratio. The results of the proposed quadrilateral higher-order plate elements are compared with the results of the first-order and higher-order theories in the literature.
Seismic Upgrading of Existing Circular RC Pier with Steel Jacket
Kim, Jae-Kwan ; Kim, Ick-Hyun ; Lim, Hyun-Woo ; Lee, Jae-Ho ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 911~920
Two scale models of RC columns with solid circular section were tested to investigate seismic behavior of bridge pier retrofitted by steel jacketing. The reference test model has lap-spliced longitudinal bars in the potential plastic hinge region and does not have sufficient amount of transverse confinement steel. Under quasi-static cyclic lateral loading the un-retrofitted model showed very brittle behavior resulting from the bond failure of lap-spliced bars. In contrast, a large amount of ductility has been achieved in the retrofitted model without bond failure. Test results confirmed that steel jacketing could be an effective seismic retrofit measure for the enhancement of flexural capacity of existing bridge piers that were constructed in moderate seismicity regions and designed for the conventional loading only.
Nominal Moment of RC Beams Strengthened with Carbon Fiber Sheets - I. Experimental Investigation -
Cheung, Jin-Hwan ; Kim, Seong-Do ; Cho, Baik-Soon ; Lee, Woo-Cheol ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 921~929
Routinely, KCI strength method for determining nominal moment of RC beam strengthened with fiber sheet is also assumed to be suitable. Flexural capacity of strengthened beam is absolutely dependent upon the type and amount of strengthening materials, anchoring system, and adhesion capacity between strengthening material and concrete. Therefore, it might be inaccurate in some region to use KCI strength method for analysis and design of strengthened beam without considering the differences in the load-deflection curves, failure mechanism, state of stress distribution, failure strain of strengthening materials, and tensile capacity of concrete. In order to analyze the effects of the carbon fiber sheets on RC beams, three types of reinforcement ratio have been selected. The effects of the amount of carbon fiber sheets on flexural capacity of strengthened beam are also examined. Systematic experimental investigations were performed for total 24 strengthened and 3 control beams. Load-deflection relations, concrete compressive strain, tensile strain of carbon fiber sheet, applied load, crack distribution and failure mechanism obtained from the experimental results were utilized in determining the flexural capacity of strengthened beams. It can be found that the concrete tensile capacity, failure strain of carbon fiber sheet, and magnitude of concrete compressive strain were the most important parameters on determining nominal moment of strengthened beam.
Nominal Moment of RC Beams Strengthened with Carbon Fiber Sheets - II. Analytical Investigation -
Cheung, Jin-Hwan ; Kim, Seong-Do ; Cho, Baik-Soon ; Lee, Woo-Cheol ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 931~938
Generally, KCI strength method for determining nominal moment of RC beam strengthened with fiber sheet is also assumed to be suitable. Flexural capacity of strengthened beam is absolutely dependent upon the strengthening system such as the type and amount of strengthening materials, anchoring system, and adhesion capacity between strengthening material and concrete. Therefore, it would be inappropriate in some extent to use KCI strength method for analysis and design of strengthened beam without considering the differences in the load-deflection curves, failure mechanism, state of stress distribution, failure strain of strengthening material, and tensile capacity of concrete. This investigation attempts to analyze the flexural behavior of a strengthened beam in three stages according to the conditions of the constituents: pre-cracking stage; pre-yielding stage; and post-yielding stage. The proposed analytical method for strengthened beams is proved to be accurate by an experimental investigation of load-deflection curve, yield load, ultimate load, and flexural rigidities in the pre- and post-yielding stages. This study also discusses the influence of concrete tensile capacity, failure strain of carbon fiber sheet, and magnitude of concrete compressive strain corresponding to failure strain of carbon fiber sheet, which are not considered in KCI strength method, on the determination of the nominal moment of the strengthened beam.
Seismic Performance Evaluation of RC Bridge Piers Confined with Spiral FRP - (I) FRP Rope -
Chung, Young-Soo ; Park, Jin-Young ; Seo, Jin-Won ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 939~946
Conventional reinforced concrete (RC) bridge piers are designed to laterally confine the core concrete inside the longitudinal steels by hoop reinforcement, and sometimes by spiral reinforcement for circular bridge columns. Recently, there are increased much concerns about innovative details of FRP confinement, as a substitute for conventional hoop and spiral reinforcing steels, which could have high strength and be easily constructed for any type of bridge pier sections due to its light weight and flexible property. The objective of this research is to evaluate the seismic performance of circular RC bridge piers laterally confined with spiral FRP rope. Six (6) circular pier specimens were made with FRP rope for transverse confinement. Potentials of new FRP confinement was verified through the Quasi-static tests.
Seismic Performance Evaluation of RC Bridge Piers Confined with Spiral FRP (II) - FRP Band-
Chung, Young-Soo ; Park, Jin-Young ; Rhee, Ji-Young ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 947~954
Because the seismic performance of reinforced concrete (RC) bridge pier is dependent on the ductility of its plastic hinge region, conventional reinforcing steels are largely used for lateral confinement of the plastic hinge region even if their high corrosion potentials and difficult fabrication and assembly, which sometimes caused to induce poor quality works. For the development of new substitute for conventional hoop and spiral reinforcing steels, this research is to investigate the confining performance of transverse FRP band, which was newly devised based on previous research for the confinement of FRP rope. Eight (8) circular pier specimens, in 600 mm diameter and 2,100 mm height, were made with FRP band for lateral confinement, of which test parameters were a space of transverse FRP band and quantity of fibers in each FRP band. It was confirmed from the quasi-static test that FRP band could be effectively used for the lateral confinement for bridge piers, and could be better than FRP rope for the seismic performance.
Methods for Strength Verification of Nodal Zones in Two-Dimensional Strut-Tie Models
Yun, Young-Mook ; Jung, Woo-Young ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 955~967
A strut-tie model approach has proven to be useful for the detailing of disturbed regions of structural concrete. This approach promotes a better understanding of force transfer mechanisms and improves the designers' ability to handle unusual circumstances. Despite the advantages of the strut-tie model approach, portions of them lack adequate definition and have not been extensively verified for use in structural analyses and designs. One of the specific areas in which further research is required is nodal zones. Before the strut-tie model approach can be practically implemented to various regions of structural concretes, a proper way of checking the strength limits of nodal zones to allow safe transfer of strut and tie forces through nodal zones must be established. In this study, literature review on the approaches for evaluating the limits of nodal zone strength was conducted, and a consistent and general approach applicable to any type of strength verification situation of two-dimensional nodal zones was proposed. The validity of the proposed approach was examined by evaluating the ultimate strength of several nodal zones which were tested to failure.
The Characteristic of Capillary Pore and Chloride Diffusivity by Electrical Difference into Various Concrete
Moon, Han-Young ; Kim, Hong-Sam ; Choi, Doo-Sun ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 969~976
Deleterious substances such as chlorides and carbon dioxides go through the pore of concrete. It is well known that making dense cement matrix enhances the durability of concrete as well as all the characteristics including strength of concrete. In this study, 12 mix concretes using 6 types of portland and blended cements, respectively, were studied on the micro-pore structure of concrete by mercury intrusion porosimetry technique and the accelerated chloride diffusivity of concrete by Electrical difference. From the results, it was concluded that there was a good co-relationship between average pore diameter and chloride diffusivity, and using the mineral admixtures had a filling effect on the pore structure of cements matrix due to those pozzolanic reaction with the hydrates of cement, which increases the tortuosity of pore and makes large pore finer.
Evaluation of Driving Safety in High Winds
Kwon, Soon-Duck ; Jeong, Un-Yong ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 977~984
This paper presents a guideline for evaluating the driving safety in high winds. Danger level for vehicle accident is derived from the side slip caused by cross wind, and then safety criteria for driving stability are defined. Dynamic model for vehicle under side wind is introduced for computing the lateral deviation from its desired path. Dynamic properties of vehicles were obtained from field tests on vehicles and wind tunnel tests. From the numerical simulations using the measured data, speed limits of small passenger vehicles is proposed.
Dynamic Characteristics of Stay Cables with Viscoelastic Damper -II. Maxwell Model-
Ahn, Sang-Sup ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 985~994
This paper obtains approximated analytic solution of cables with viscoelastic fluid damper in order to identify the dynamic characteristics of such system. Numerical schemes to solve response under dynamic loads are also studied. Viscoelastic fluid dampers are commonly used as cable dampers because of their definite dynamic behavior and high damping performance among passive dampers. This type of damper can be simulated with Maxwell model consisting of a dashpot connected in series to a linear spring. Approximated analytic solutions including additional damping ratio, displacement at the cable and damper, damper force, etc. are obtained for the taut cable assuming the damper installation position not far from the near anchorage. On the other hand, the cable sag is considered in the numerical solution scheme and the installation position of damper is no longer restricted. Moreover damper force of Maxwell damper is considered in the numerical scheme in the incremental form which makes the time integration much easier. The static deflection shape of cable subject to the concentrated load at the damper installation position is taken as the first shape function of cable-damper system. The other shape functions are taken as usual sine series. By this, we can significantly improve the series convergence and provide efficient analysis of cable-damper system including passive, active and semi-active damper. The approximated analytic solutions for the cable with Maxwell damper can also be obtained using the equivalent relation to the Kelvin damper. Finally we verify the approximated analytic solutions by comparing the dynamic response with numerical solutions.
Earthquake Resistant Design and Behavior Factor for a Typical Steel Box Girder Roadway Bridge
Kook, Seung-Kyu ; Cheung, Jin-Hwan ; Choi, Kwang-Kyu ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 995~1001
The basic design concept of the earthquake resistant design of 'Roadway Bridge Design Criteria' requires both serviceability of structures under earthquakes with high probability of occurrence during the design life and no collapse of structures suffering local damages under earthquakes such as design earthquake with low probability of occurrence. The earthquake resistant design provisions provide a design method using design earthquake with response modification factors for satisfying the no collapse requirement. However such a method does not ensure verification of the basic design concept. In this study a 5-span steel box girder bridge is selected and analysed according to the earthquake resistant design provisions. Based on the analysis results are provided verification/design methods satisfying the basic design concept.
Shear Buckling Coefficients of Singly Symmetric Plate Girder Web
Gil, Heung-Bae ; Kim, Kyu-Nam ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 1003~1010
The web of plate girders can fail by bend buckling and/or shear buckling because it is subjected to bending moment and shear. To prevent buckling of the plate girder, the thickness of the web is increased, and longitudinal and transverse stiffeners are attached. The joint between the web and flanges have partial rigidity due to torsional stiffness of flanges. However, most of specifications neglect torsional stiffness of flanges and assume that the web is simply supported at web-flanges joints. On the contrary, an increase in the bend buckling strength due to stiffness of flanges is considered in some specifications. In recent years, cross-section of the plate girder is simplified to reduce fabrication and maintenance efforts. To do that, number of transverse stiffeners on the web are minimized and thicker web plates are used. Longitudinal stiffeners are typically removed. Understanding of strength of the web is necessary for safe and economics design of these simplified plate girders. This paper deals with research performed to define shear buckling coefficients of singly symmetric plate girder with different flange widths.
Ultimate Strength of CFT Short Columns Considering the Confining Effect of Concrete
Hwang, Won-Sup ; Kim, Dong-Jo ; Jung, Dae-An ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 1011~1018
This paper provides the estimation of the confining stress for the concrete-filled steel tubular (CFT) short columns. The effects of width-thickness and diameter-thickness ratio on the gap force for the CFT columns are investigated through the finite element analysis. The informations on the effects of steel and concrete strength are also reported herein. Based on the results, some new proposals of the ultimate strength of the CFT short columns are presented. Futhermore the procedure is compared with the previous experimental results and the current design equations.
Free Vibration and Mode Characteristic of Laminated Composite Folded Plate Roof
Chun, Kyoung-Sik ; Kim, Jong-Soo ; Chang, Suk-Yoon ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 1019~1028
Laminated composite folded plate structure has been widely used in many fields such as folded-plate wall, silo, all kinds of containers, shipbuilding and civil fields. Therefore, there are real, practical needs for researching folded plate structure in the paper. An improved 4-noded quadrilateral flat/shell element that incorporates higher-order shear deformation and in-plane drilling rotational degree of freedom is used to study the free vibration and mode characteristic of laminated composite folded plates. The element has eight degrees-of-freedom per node. Several numerical examples are presented and results are compared with those available in the literature. Parametric studies are conducted for free and forced vibration analysis for laminated composite non-prismatic folded plates, with reference to aspect ratio, crank angle, fiber angle and stacking sequence. The natural frequencies and mode shape, and forced vibration responses analyzed here may serve as a benchmark for future investigations.
Seismic Damage Evaluation of Reinforced Concrete Pier Based on a Plastic Damage Model
Koh, Hyun-Moo ; Lee, Jee-Ho ; Kang, Jun-Won ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 1029~1039
A new method to evaluate seismic risk of reinforced concrete piers without computing their ultimate deformation is developed based on two newly proposed global damage indices. The suggested global damage indices, representing the maximum of cross sectional damage and damage average over the structural volume, are formulated in terms of the local damage variable in Lee and Fenves's plastic-damage model. From the computational seismic risk analysis of experimentally tested reinforced concrete piers, it is observed that the proposed seismic risk evaluation method works appropriately and the present two-damage-indices approach provides a practical and useful global damage level analysis tool for reinforced concrete pier structures.
Ultimate Strength Behavior of Compression Flanges in Steel Box Girder Bridges - (I) Ultimate Strength of Flanges -
Yoon, Dong-Yong ; Lee, Doo-Sung ; Lee, Sung-Chul ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 1041~1048
This paper presents an investigation on the ultimate strength behavior of sub-panels of stiffened wide compression flanges used in steel box girder bridges. For designs of the stiffened wide compression flanges, AASHTO LRFD (1994) treats the sub-panels divided by equally spaced longitudinal stiffeners as individually supported panels. This method better describes the overall flange behavior than so-called the strut method when small number of stiffeners are used. Although a considerable post-buckling reserve may be expected after elastic buckling of relatively thin sub-panels as known for unstiffened rectangular panels supported at all four edges, AASHTO LRFD (1994) does not include the reserved strength. Exclusion of the post-buckling strength may result in too conservative design in the large slenderness ratio and the high strength steel flange. However, it is found that the AASHTO design curve may overestimate the strength for thick flanges due to an incorrect reflection of the reducing effects of initial imperfections. From a parametric study based on the results of the nonlinear finite element analysis, new design equations are formulated for the estimation of the ultimate compressive strength of flanges.
Ultimate Strength Behavior of Compression Flanges in Steel Box Girder Bridges - (II) Ultimate Optimum Rigidity of Longitudinal Stiffeners -
Yoon, Dong-Yong ; Lee, Doo-Sung ; Lee, Sung-Chul ;
Journal of The Korean Society of Civil Engineers, volume 23, issue 5A, 2003, Pages 1049~1056
The sub-panel method for stiffened compression flanges treats the sub-panels divided by equally spaced longitudinal stiffeners as individually supported panels. Yoon et al. (2003) found that the sub-panels are capable to develop a considerable post-buckling strength if the longitudinal stiffeners are rigid enough to form the nodal-line after buckling. This paper presents an investigation on the ultimate strength behavior of longitudinal stiffener in wide compression flange used in steel box girders bridges. The elastic buckling behavior of the longitudinal stiffeners and stiffened flanges are different from the ultimate strength behavior. However, it is revealed that the design rules for longitudinal stiffeners based on the elastic buckling theory are not appropriate for the ultimate strength design. A new equation is suggested for determination moment of inertia of stiffeners that is necessary for the sub-panels to have a potential strength equivalent to that of simply supported unstiffened panels