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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
Probability Fatigue Failure Models of Pavement Concrete Subjected to Split Tensile Repeated-Loads
Kim, Dong-Ho ; Lee, Ju-Hyung ; Yun, Kyong-Ku ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 861~867
The purpose of this paper was to analyze the fatigue behaviors and to develope the probability failure models of pavement concrete, subjected to split tensional repeated-loads. The fatigue behavior analysis was based on the reliability analysis for the experimental fatigue data, using Weibull probability distribution function. The Weibull's parameters were obtained using graphic, moment and maximum likelihood estimation methods. The fatigue tests were performed at 3 stress levels (70,80, and 90%) of 0.1 stress ratio, sine wave loading and 20 Hz frequency, using a split tensional specimens of 150 mm diameter and 75 mm thickness. The results are as follows; The Weibull distributions for fatigue life of pavement concrete were determined for various stress levels. Using the average values of two parameters (
) in Weibull distribution, the probability fatigue failure models of pavement concrete, subjected to split tensional repeated-loads, were proposed. The goodness-of-fit test by Kolmogorov-Smirnov test was acceptable at 5% significance level.
Design Live Loads for Exclusive Uses in Overpasses for Passenger Cars
Kim, Sang-Jin ; Kim, Jin-Woo ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 869~878
The purpose of this study is to develop a live load model for the design and construction of overpasses for passenger cars. The live loads of passenger cars that are developed in this study correspond to the truck live loads in the existing bridge design standards. A survey for the dimensions and weights of passenger cars is necessary to develop design live loads. The dimensions of design cars are determined from the survey of cars that are produced in Korea in 2002. The car weight data are taken from the weight survey data for the development of design live loads for passenger cars parking garages in the USA. The data of car dimensions and weight are used to calculate the maximum load effects of moment and shear in structures. The probability distribution of the extreme load effects for the design life of the structure is determined from the statistical analysis of the maximum load effects. The equivalent uniformly distributed lane loads are calculated from the probability distribution of the extreme load effects. The uniformly distributed lane loads have to be applied for the design of long span bridges. The magnitude of the design lane load is 470 kgf/m for a span length of 20 m. The magnitude increases as the span decreases, and decreases as the span increases. For short span bridges or slabs, one passenger car can be loaded. Therefore, a design passenger car has been developed. The weight of a design passenger car for the design of a short span bridge is 4.5 tonf.
Earthquake Resistant Design for a Bridge with II Type Piers
Kook, Seung-Kyu ; Jung, Beom-Seok ; Choi, Jong-Man ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 879~884
'Roadway Bridge Design Criteria' requires both serviceability and no collapse of bridges as the basic design concept of the earthquake resistant design requiring particular performances under earthquakes. The earthquake resistant design provisions provide a design method using design earthquake with response modification factors for satisfying the no collapse requirement, however verification methods for the fulfillment of both requirements are not provided. Therefore, for bridges in low to moderate seismic regions, such a method does not ensure fulfillment of the basic design concept. In this study a bridge with II type piers is selected and analysed according to the earthquake resistant design provisions. Based on the analysis results are provided design procedure as well as verification methods satisfying the basic design concept.
A formulation for Response Variability due to Uncertain Material Constant in Nonlinear Form
Noh, Hyuk-Chun ; Song, Myung-Kwan ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 885~894
In this paper, a new formulation to analyze the response variability due to the randomness in nonlinear material constant such as the Poisson's ratio is presented. Since the Poisson's ratio, together with elastic modulus, is a material constant which influences the behavior of structures, the independent evaluation of the effects of this parameter on the response variability is of importance. To overcome the difficulties in obtaining the response variability caused by the nonlinearity in Poisson's ratio, the constitutive matrix is stochastically expanded into several sub-matrices taking into consideration of the polynomial expansion on the coefficients of constitutive matrix. To illustrate the accuracy of the proposed formulation, some example structures are chosen and the results are compared with those obtained by means of classical Monte Carlo simulation. Through the formulation proposed in this study, it becomes possible for the non-statistical weighted integral stochastic finite element analysis to consider all the uncertain material parameters in its application.
Design of Passive Control System for Seismically Excited Cable-Stayed Bridges
Lee, Sung-Jin ; Park, Kyu-Sik ; Lee, Jong-Heon ; Lee, In-Won ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 895~907
In this paper, the design procedure and guideline of LRB are proposed and the effectiveness of designed LRB is investigated for a seismically excited cable-stayed bridge. The design index (DI) and procedure of LRB for cable-stayed bridge are proposed and appropriate LRB is selected when the proposed DI value is minimized or converged for variation of properties of LRB. The design result shows that the damping and energy dissipation effect of LRB are more important than the shift of the natural period of structures for cable-stayed bridge. The control performance of designed LRB is also verified and the result shows that seismic responses of cable-stayed bridge are controlled sufficiently by LRB. Furthermore, the sensitivity analyses of properties of LRB are conducted for different characteristics of earthquake. The performance of designed LRB is not changed significantly and thus the robustness of designed LRB is verified for these. Finally the VD is designed and employed to obtain the additional reduction of seismic responses which are not reduced sufficiently by only LRB.
A Study on the Structural Behavior and Construction method for Preventing Crack under Construction of Precast Segmental Box Girder Bridges through the Construction Sequences Analysis
Sim, Jong-Sung ; Moon, Do-Young ; Kim, Young-Ho ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 909~914
The crack that occurred in bottom slab of precast segmental bridge is investigated through construction sequences analysis and caused by excessive deformation at temporary post-tensioning for joining the segments in this study. Also parametric study is performed to evaluate the effect of the thickness of bottom slab, order and position of prestressing. The structural behavior of girder section is greatly affected by the thickness of bottom slab and position of post-tensioning than prestressing order. Therefore, construction method for preventing cracks under construction is presented.
Flexural Strengthening Effect of Reinforced Concrete Slabs Bonded with Carbon FRP Grid
Park, Sang-Yeol ; Choe, Hyeon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 915~921
This paper presents the strengthening effect and the behavior of reinforced concrete slab strengthened with Carbon Fiber Reinforced Polymer (CFRP) grid. Parameters involved in this experimental study are FRP grid reinforcement quantity, repair mortar thickness, presence of anchor, and the location of strengthening. Generally, flexural members strengthened with reinforcement material (sheet, plate) made of Fiber Reinforced Polymer (FRP) have the failures, such as delamination failure debonding failure before reaching the maximum stress of FRP reinforcement. However, in this study there are various failure types with increasing the strengthening reinforcement. On the moderate strengthening level, there is a failure in the interface of carbon FRP grid because of the excessive shear deformation. On the other hand, there is a failure in shear on the high strengthening level. With the increasing of FRP grid reinforcement, the strengthening effect in flexure increased, but the ductility decreased. By limiting the strengthening level, it can be achieved to prevent shear failure, to increase the efficiency in strengthening, and to improve the ductility.
A Study on the Core Confinement Method of Reinforced Concrete Piers
Shu, Jin-Won ; Rhee, Ji-Young ; Ko, Seong-Hyun ; Lee, Jae-Hoon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 923~929
Reinforced concrete bridge columns can be subjected to a series of earthquake excitations as well as axial loads. Transverse reinforcement bars are used in the plastic hinge zone of columns to ensure ductile behavior. Fabrication and placement of those bars in columns is difficult and labor-intensive. Moreover columns with rectangular cross-section require cross-ties and/or overlapping ties in addition to the perimeter ties in order to provide adequate confinement and prevent bar buckling. To solve these problems, the confinement method using interlocking reinforcement is proposed for the transverse confinement of columns of the oblong cross-section. The experimental study for oblong cross-section was carried out by the column test in weak axis and strong axis. The column specimens had 3 types of transverse steel details, such as interlocking spirals(IS), interlocking circular hoop ties(IC), and rectangular ties(RT). The oblong columns with interlocking spirals and with interlocking circular hoop ties showed better seismic performance than the rectangular columns with hoops and cross-ties. Interlocking circular hoop ties, which use the same circular hoop ties as the circular cross-section, considerably reduce the amount of transverse reinforcement than the rectangular ties by about 50%. Connection of rebars can also be simplified. It can be the alternative for oblong section with improved workability and cost-efficiency.
Forced Vibration of Laminated Composite Plates With Damage Region By Various Fiber Angles
Lee, Sang-Youl ; Chang, Suk-Yoon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 931~937
This study deals with effects of fiber angles on the forced vibration of anisotropic composite plates under arbitrary impact loads with damage region. Based on high order shear deformation theory, a 7-DOF finite element method using combined Lagrangian and Hermite interpolation functions is presented. In this paper, the damage of laminated composite plate is defined as the assemblage of the element stiffness matrices multiplied by a stiffness reduction factor. The result analyzed by developed computer program shows good agreement with that of the available literature. Sample numerical examples using various parameters are focused on analysing complex interactions between fiber angles and extents of arbitrary damages which make significant influences on the dynamic behaviors of laminated composite plate.
An Improved Stresses Recovery based on the Hybrid Stress Method for 4-node EAS Plate Elements
Park, Dae-Yong ; Chun, Kyoung-Sik ; Yhim, Sung-Soon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 939~949
In this paper, a
continuity four-node Reissner-Mindlin plate element is used for analyzing the isotropic and laminated composite plates. The substitute shear strain field directly derived by Jacobian Matrix is used to avoid the locking and spurious zero energy modes. The EAS(Enhanced Assumed Strain) method also is employed to improve in-plane and out-of-plane behavior in Reissner-Mindlin plates. To estimate the exact stresses and stress resultants of the four-node EAS plate element, an improved stress recovery method based on hybrid stress method with parameter is proposed. The four-node EAS plate element using the improved stress recovery method is referred to as "EAS-QTP4b" in this paper. The various numerical tests for not only isotropic but also laminated composite plates are presented. It is shown that the numerical results using "EAS-QTP4" provide an improved stresses and stress resultants when comparing to the results of other researchers.
Estimation of Ship Collision Energy on the Bridge
Lee, Seong-Lo ; Lee, Gye-Hee ; Lee, Wan-Soo ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 951~960
The kinetic energy during ship collision with bridge piers is released as the permanent deformations of structure and friction between the impact surfaces. So the ship collision energy on pier is estimated from the equations of motions for ship-pier collisions which include the influence of the surrounding water, different impact angles and impact locations. The normal impact energy and tangent impact energy at a collision location and angle can be transformed into the normal impact force and friction force acting on the structure. Also the kinetic energy after collision is calculated from the linear and angular impulse of ship collision. The collision energy absorption system such as the protective structures for bridges will be designed by evaluating the damage portions of ship and structure during the ship-structure collisions varying from the soft impact to hard impact and then the estimation. of it will be suited for the design of protective measures.
Development of Optimum Cost Formula with Optimum Design for PSC Box Girder Bridges
Kim, Ki-Wook ; Park, Moon-Ho ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 961~968
It developed the optimum design program to minimize the cost for psc box girder bridge by using full_staging method and used totally optimized cost's correlation to cell number, span length, and lane number. Thus, it is simply able to compute the optimal cost by substituting cell number, span length, lane number and declared the simple & precise formulas which can be readily used in fields. It also verified the formulas using correlation analysis, regression analysis, variation analysis, residual and suitable precision. Technical solution of optimum design program used SUMT procedure, and Kavlie's extended penalty function to allow infeasible design points in the process. Powell's direct method was used in searching design points and Gradient's approximate method was used to reduce design hours.
Bond Performance of Ductile Hybrid FRP Reinforcing Bar After Accelerated Environmental Exposures
Won, Jong-Pil ; Park, Chan-Gi ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 969~979
The most obvious benefit of the FRP material is perhaps the fact that it does not corrode in the same way as steel. But, FRP rebar has lower bond performance than steel rebar. Usually, FRP rebar has about 60% of bond strength of steel rebar. Without adequate bond to concrete, the full composite action between reinforcement and concrete matrix can not be achieved. Therefore FRP rebars must also have surface deformations that provide good bond to concrete. Current methods of providing surface deformation to FRP rebars include helical wrapping, surface sand coating and rib molding. The problem with the helical wrapping method is that it can not provide enough surface deformation for good bond and it can be easily sheard off from the FRP rebars. Sand coation and rib molding provide surface deformation only to the outer FRP skins. In this study focuses on bond properties of hybrid FRP rebar after environmental exposure Hybrid FRP rebar bond specimens were subjected to twelve type of exposure conditions including alkaline solution, acid solution, salt solution and deionized water etc. Bond properties were investigated by direct bond test. According to bond test results, hybrid FRP rebars were found to have better bond strength with concrete than currently using GFRP rebar. Also, hybrid FRP rebar had more than about 80% in bond strength of steel rebar.
An Experimental Study on the Durability of the High Performance Shotcrete
Kwon, So-Jin ; Lee, Sung-Kwon ; Kim, Kyoung-Nam ; Jung, Kyoung-Sup ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 981~991
There is an increasing interest in utilizing shotcrete for permanent tunnel linings. With this concern, the durability of shotcrete is of great importance. Shotcrete is a very complex production process, involving a number of possible concrete admixtures, as well as an accelerator. Equipment type and condition, quantity of compressed air, efficiency of spraying nozzle, spraying angle and distance, application procedure, time related effects and curing conditions are examples of factors influencing durability. This study focuses on specifying the influencing factors for durability of shotcrete. To examine the durability of shotcrete, three types of strength test, Freeze-thaw test, chloride penetration test and accelerated carbonation test are conducted on 15 mixes. The main test variables include different type of accelerators, super-plasticizers and admixtures. From the present comprehensive test results, the factors influencing durability of shotcrete are investigated. The present study will enable the improvement on shotcrete performance and economic construction.
An Experimental Study on flexural Behavior of I-beams Partially Encased in Slab
Jo, Byung-Wan ; Kim, Chang-Hyun ; Lee, Du-Hwa ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 993~998
I-beams partially encased in slab consist of rolled steel sections, which are relatively closely spaced and encased in concrete without specific mechanical shear connection means. Based on experimental research, recommendations of flexural design are suggested. In order to determine the maximum flexural strength, the alternative rigid plastic analysis is applied. The effective inertia moment may be taken the mean of the cracked and uncracked values of second moment of the composite section. The area of concrete in compression may be determined from the plastic stress distribution.
A Numerical Model for Plastic Shrinkage Cracking of Concrete Slab
Kwak, Hyo-Gyoung ; Ha, Soo-Jun ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 999~1009
In this paper, an analytical model which can predict the occurrence of plastic shrinkage cracking on slabs is introduced on the basis of the balance between bleed water and its evaporation. To estimate the amount of bleed water and its occurrence rate in concrete slabs, the consolidation model proposed by Tan et al. (1987) and applied to the cement paste is used after comparison of the analytical results with the experimental results. In advance, the effect of temperature variation on the evaporation rate, caused by the hydration heat of concrete matrix, is taken into consideration. Finally, the time at which the concrete surface begins to dry and the time at which plastic shrinkage cracks occur can be estimated using above two analytical models. Through correlation studies between experimental data and analytical results, it is verified that the proposed model can predict the occurrence of plastic shrinkage cracking with comparative precision.
Analysis of Carbonation Behavior of Cracked Concrete in Early - Age
Kwon, Seung-Jun ; Song, Ha-Won ; Byun, Keun-Joo ; Lee, Seung-Hoon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1011~1022
The carbonation on cracked concrete is considered as one of major deteriorations causing steel corrosion in RC structures. For durable concrete structures, it is necessary to control crack in concrete through the crack resistance evaluation, but often unavoidable cracks in early-age may occur. These cracks become a main path of
penetration inside concrete so that the carbonation is accelerated in cracked concrete. In this study, a diffusivity in cracked concrete is derived by considering both
diffusion in pore water in sound concrete,
diffusion in crack width and analysis technique for carbonation on cracked concrete in early-age. The characteristics of diffusivity on the carbonation in early-age concrete is studied through finite element analysis of early-age concrete using multicomponent heat hydration model and micro structure formation model. Then, the carbonation behavior in sound and cracked concrete is simulated by using the derived diffusivity with consideration of reaction with dissolved
. Finally, numerical analysis result obtained for concretes made with 3 different W/C ratios(45%, 55%, 65%) and various crack width(
) is compared with experimental results.
Steel Jacketing for Enhanced Flexural Ductility of Damaged Column
Youm, Kwang-Soo ; Yoon, Ki-Yong ; Lee, Hak-Eun ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1023~1030
The objectives of this study to investigate seismic repair performance of damaged circular reinforced concrete bridge columns by steel jacket.9 RC columns were designed by lateral confinement ratio 0.6%, 1.1% and 2.1% respectively. After each specimen was tested by cyclic and monotonic load test, damaged columns repaired by steel jacket. The test results of damaged circular RC columns with a steel jacket showed an enhanced performance of the flexural ductility and the verification of repair effect of steel jacketing.
Design Method of Energy Absorbing Device(EAD) Considering Occupant Safety of Impact Vehicle
Ko, Man-Gi ; Kim, Kee-Dong ; Kim, Kyoung-Ju ; Sung, Jung-Gon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1031~1041
For an effective design of Energy Absorbing Device(EAD), understanding vehicle motion during impact and mechanical properties of the EAD is essential. In this paper, structural parmeters affecting occupant safety have been identified and studied using 2-DOF System model decribring vehicle crash against EAD with various mechanical properties. From the study two design equations have been developed, which can be used for the design of any EAD system with design conditions of 1.3ton car head-on impact with 60 km/h and 80 km/h impact speeds.
Crashworthiness of Steel Tube Under Transverse Loading
Ko, Man-Gi ; Kim, Kee-Dong ; Kim, Kyoung-Ju ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1043~1051
Steel Tube (
) is a potential structural element that can be used for an Enegry Absorbing Device(EAD) to shield objects having various configurations and if the tubes were assembed in multiple layers to form an EAD system, it can have wide range of energy absorbing capabilities. To study the crashworthiness of the steel tube static transverse loading test using loading plate of
size have been conducted. Steel tubes of two different length of 250 mm and 500 mm were tested and the influence of relative size of tube length to loading plate on crashworthiness was studied. Test results were compared with the LS-DYNA simulation and 4-Hinge Mechanism Analysis. Drop tests of 4m maximum drop height were conducted using 300 kg mass and the results were compared with static load test results.
Dynamic Impact Load and Performance Evaluation of Concrete Rigid Barriers
Woo, Kwang-Sung ; Kim, Jae-Il ; Ra, Jin-Soo ; Ahn, Sang-Seob ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1053~1063
In this study the useful formula is proposed to estimate the lateral impact forces with respect to the different design level varying from SB1 to SB6 for concrete rigid barriers, since the guideline of lateral impact load of concrete rigid barriers in domestic and foreign design codes does not reflect all possible collision conditions such as shape of barrier, weight of vehicle, impact velocity and impact angle. For this purpose, HVOSM and LS/DYNA-3D programs are used to analyze the three-dimensional nonlinear dynamic behaviour, especially acceleration of vehicle after collision. The occupant risk has been evaluated for F-type, NJ-type, 55-type, and two different type of barriers proposed by Korea Highway Corporation as well as vehicle stability in terms of critical override velocity and critical overturn velocity. Also, the ultimate loads of concrete rigid barriers are compared each other for different design parameters like concrete strength, arrangement and size of upper and lower rebars, yield strength of steel, and concrete cover depth.
Analytical Study on the Shear Behavior of Reinforced Concrete Continuous Deep Beams
Kim, Tae-Hoon ; Rhee, Jong-Woo ; Chung, Young-Soo ; Shin, Hyun-Mock ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1065~1072
The purpose of this study is to investigate the shear behavior of reinforced concrete continuous deep beams and to provide the data for developing improved design criteria. 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 reinforced concrete structures was used. 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. The proposed numerical method for the shear behavior of rein forced concrete continuous deep beams is verified by comparison with reliable experimental results.
Nonlinear Finite Element Analysis of Reinforced Concrete Structures using Elasto-Plastic Material Model
Lee, Hong-Pyo ; Choun, Young-Sun ; Shin, Jae-Chul ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1073~1082
This study describes a standard 8-node shell FE element using an elasto-plastic material model for nonlinear analysis of reinforced concrete structures. Reissner-Mindlin(RM) assumptions are adopted to develop the degenerated shell FE so that transverse shear deformation effects is considered. Drucker-Prager failure criterion in compression region and Aoyagi-Yamada failure criterion in tension region are used to model the constitutive behavior of concrete. The concrete material model take into account the aspects of tension stiffening, compression strength reduction of concrete and shear transfer to improve the accuracy of FE analysis. The arc-length method is adapted to overcome the difficulties of post peak load analysis and snap through phenomena. RM shell formulation is provided in this paper with emphasis on the terms related to the stiffness matrix based on degenerated solid concept and elasto-plastic material model. Finally, the performance of the present shell element is tested and demonstrated with several numerical examples. The numerical results by this model agree very well with the experimental data available and other numerical results.
Nonlinear Seismic Deformation Analysis of RC Bridge Piers
Lee, Do-Hyung ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1083~1091
In this paper, effect of deformation mechanism on the damage of reinforced concrete piers subjected to earthquake loading is investigated. For this purpose, shear-axial interaction model is presented and implemented into a nonlinear structural analysis program. Comparative study has been carried out for reinforced concrete column tests and shows that predicted shear hysteretic response agrees well with the test results. Also conducted is a nonlinear time-history analysis of a reinforced concrete bridge damaged by the Kobe earthquake using the current development. The evaluation of displacement response for piers reveals that maximum displacement is considerably increased due to the effect of shear coupled with axial force variation, which leads to overall stiffness degradation and period elongation. It is therefore encouraging that the present development can be used to identify the contribution of deformation mechanisms.
Probabilistic Seismic Safety Assessment of Bridges Utilizing Measured Response Data
Yi, Jin-Hak ; Kim, Sang-Hoon ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1093~1102
This paper presents the first effort in probabilistic seismic safety assessment of a structure using a correlated analysis model based on measured response data. An instrumented highway bridge is used to demonstrate the analysis procedure involving measuring ambient vibration, identifying modal parameters from the measured data, updating a preliminary analysis model (obtained from structural design drawings) utilizing the measured modal parameters, analyzing nonlinear response time histories of the structure under earthquake excitations, and finally evaluating probabilistic seismic safety of a structure. The seismic safety of a highway bridge can be more reliably evaluated by utilizing the measured data and correlated analysis model incorporating structural identification method.
Dynamic Behaviors and Failure Probability of Bridges under Combined Effects of Earthquake and Local Scour
Kim, Sang-Hyo ; Mha, Ho-Seong ; Lee, Sang-Woo ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1103~1110
The effects of various scour conditions upon dynamic responses of bridges under seismic excitations are examined, and the failure probability of a foundation due to the combined effect of the seismic loading and local scour around the pier foundation are investigated. A realistic case study is performed with the probabilistic characteristics of scour depths evaluated based on the hydraulic data collected from a middle size river in Korea. The seismic responses of a multi-span simply supported bridge with deep foundations are evaluated using a simplified mechanical bridge model. From the simulated results, the local scour condition is found to cause the larger seismic responses of bridges. The local scour effect is quite significant under weak seismic excitations, in which the seismic responses may be underestimated significantly without considering the reduced embedded depths. Even for moderate seismic excitations, the local scour effect is notable. The recovery durations of the foundation stiffness from local scour condition are found to be critical in the estimation of the failure probability of a foundation under earthquakes. Therefore, the seismic safety of a bridge should be conducted with considering the local scour effect around the foundations and the recovery duration of stiffness should be determined rationally.
Prediction Model on Autogenous Shrinkage of High Performance Concrete with Mineral Admixture
Yoo, Sung-Won ; Kim, Do-Gyum ; Kho, Kyung-Taek ; Jung, Sang-Hwa ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1111~1118
Recently, it is noticed that autogenous shrinkage of high-performance concrete as well as hydration heat causes early crack in concrete structures. The purpose of the present study is to explore the autogenous shrinkage of high-performance concrete with mineral admixture and to derive a realistic equation to estimate the autogenous shrinkage model of that. For this purpose, several series of concrete specimens have been tested. Major test variables were the type and contents of mineral admixture and water-binder ratio is fixed with 30%. The flow rate, compressive strength and autogenous shrinkage were measured for the specimens. The present study indicates that the test specimens have the properties of high-performance concrete. The autogenous shrinkage of HPC with fly ash slightly decreased than that of OPC concrete, but the use of blast furnace slag and silica fume increased with the autogenous shrinkage. A prediction equation to estimate the autogenous shrinkage of HPC with mineral admixture was derived and proposed in this study. The proposed equation show reasonably good correlation with test data on autogenous shrinkage of HPC with mineral admixture.
Adaptive Analysis with Mesh-free Method using the Double Projection method (2) -Adaptive Refinement-
Lee, Gye-Hee ; Chung, Heung-Jin ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1119~1125
The adaptive analysis and refinement of mesh-free method based on improved error estimating scheme called “double projection method” were presented. This is succeeding study of our previous paper on double projection method for reducing the spurious oscillation of error distribution. In this paper, a new algorithm for adaptive refinement which makes an advantage of smoothed distribution of error from double projection method were proposed. Since the distribution of double projected error is very similar to real one, there would be no need of iterative analysis, error estimation and refinement in adaptive process; the process of error estimation and refinement is performed for one time and refinement can be iterated several times. To present the efficiency of proposed adaptive refinement using double projected error, the numerical experiments were performed to several linear two-dimensional problems. The results showed remarkable improvement of convergence ratios compare to those of previous projection method. Moreover, if the more precise refinement scheme is adopted, the better result could be obtained.
Moment Gradient Correction Factor
Lim, Nam-Hyoung ;
Journal of The Korean Society of Civil Engineers, volume 24, issue 5A, 2004, Pages 1127~1135
This paper investigates the elastic lateral-torsional buckling of I-beams under linear moment gradient that very precisely incorporates the effects of moment gradient and various end restraints. The elastic critical buckling moments are obtained independently by using: (1) the Bubnov-Galerkin method and (2) the finite element method. The present formula of the moment gradient correction factor cannot satisfactorily predict the buckling capacities of doubly symmetric and monosymmetric I-beams with various end restraints. This paper propose alternative equations for evaluating the moment gradient correction factor, considering end restraint conditions.