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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 16, Issue 3_6 - Nov 1996
Volume 16, Issue 2_6 - Nov 1996
Volume 16, Issue 1_6 - Nov 1996
Volume 16, Issue 3_5 - Sep 1996
Volume 16, Issue 2_5 - Sep 1996
Volume 16, Issue 1_5 - Sep 1996
Volume 16, Issue 3_4 - Jul 1996
Volume 16, Issue 2_4 - Jul 1996
Volume 16, Issue 1_4 - Jul 1996
Volume 16, Issue 3_3 - May 1996
Volume 16, Issue 2_3 - May 1996
Volume 16, Issue 1_3 - May 1996
Volume 16, Issue 3_2 - Mar 1996
Volume 16, Issue 2_2 - Mar 1996
Volume 16, Issue 1_2 - Mar 1996
Volume 16, Issue 3_1 - Jan 1996
Volume 16, Issue 2_1 - Jan 1996
Volume 16, Issue 1_1 - Jan 1996
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Temperature Analysis of Mass-Concrete Structure with Pipe Cooling
Kim, Eun-Kyum ; Kim, Lae-Hyun ; Shin, Chee-Burm ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 369~369
The usual methods for the temperature control of mass-concrete structures include the use of low-heat cement, pre-cooling, or pipe-cooling. In order to control the heat of hydration of mass-concrete structures such as massive pier or anchor block, and mat foundation, the pipe cooling method is widely acceptable for pratical use. In this paper the effect of pipe cooling for mass-concrete structures was analysed by solving a 3-dimensional heat-transfer problem. A pseudo 3-dimensional finite element method was proposed in order to express the 3-dimensional effect of pipe cooling and to cut down computing time. The result of analysis agreed well with experimental data of "KUMATANI". The results of this study may be useful for the optimal design of the pipe-cooling system for mass-concrete structures.
Optimization of Steel Box Girder Bridges Using Discrete Design Variables
Kim, Sang-Hyo ; Lee, Sang-Ho ; Lee, Min-Koo ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 377~377
In this study, a rational optimization algorithm is developed to provide preliminary designs of steel-box girder bridges with optimum construction cost and the sensitivity analysis on various design variables has been performed using the developed optimization program. Due to many advantages, when comparing with other open-section girder types, such as higher torsional rigidity, better resistance against corrosion, the steel-box girder deck is widely adopted for middle and long-span bridges. In current design practice, the design variables of steel-box girder are selected mainly on the basis of engineer's experience and direct observation. Then the assumed sections are checked for design limit states. Therefore, the resulted design sections are doubtful in the optimum viewpoint. To achieve more rational design, systematic design procedure is required. by which the design constraints on steel-box girder are satisfied and the design variables with minimum cost are obtained. In most design practice, design variables are discrete rather than continuous. In the proposed optimum design process, the design variables are forced to be selected from the available discrete value set. The efficiency of the developed program has been verified by designing various examples and the resulting optimum cost with discrete variables has been compared with those of continuous variables. Based on the sensitivity analysis of optimum section, some essential guidelines for rational design of steel-box girder bridges are suggested.
A Study on Determination of the Maximum Traffic Live Load Effects for Bridges
Shim, Jae-Soo ; Hwang, Eui-Seung ; Ha, Jun-Su ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 387~387
Recently it is reported in many countries including Korea that bridges are seriously damaged due to increasing volume of overloaded vehicles. Since the safety of bridges are highly related to the design load level and extreme effects induced by traffic loads during their lifetime, it is important to determine the design live load to properly represent the load effect of the current truck traffic. The live load effect depends on many parameters including the span length, truck weight, axle loads, axle configuration, headway distance, heavy vehicle proportion, position of the vehicle on the bridge, and number of vehicles on the bridge. The objective of the study is to determine maximum effects of vehicle loadings based on the survey data collected and to evaluate the current design code. Several citation data were collected and two cases are considered : single truck and two trucks on the bridge. The maximum traffic live load effects for simple span and two equal continuous span bridges were calculated. As a result of this study, the live load effect of the current design code is relatively low at short-span (about 10m) and at span length of bifurcation point of DB-24 truck load and DL-24 lane load. Also shear forces of simple span is relatively lower than bending moments.
Inelastic Second-Order Analysis for Steel Structure Design
Kim, Seung-Eock ; Kim, Sang-Hyo ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 399~399
This paper presents practical inelastic second-order analysis for a two-dimensional steel structure design. Herein, key factors influencing steel structure behavior are described including. gradual yielding associated with flexure; residual stresses; second-order effects; and geometric imperfections, and simple approaches to enable designers to assess this behavior are provided. The proposed method incorporates the refined plastic-hinge concept for spread of plasticity together with a practical explicit imperfection modeling approach. The strengths predicted by the proposed method are then compared with those predicted by the exact plastic-zone analysis as well as by tile conventional LRFD procedure. A good agreement is generally observed. The displacement predictions are also compared with the plastic-zone solutions. Analysis and design guidelines in using the proposed methods are given in detail. Member sizes determined by the proposed method are compared with those determined by the LRFD method. The proposed method can assess realistically both strength and behavior of a structural system and its individual members in a direct manner. As a result, the method can be used for design without tedious separate member capacity checks, including the calculations of K-factor. It is concluded that the proposed procedures are suitable for adoption in practice.
Stability and Free Vibration of Rectangular Thin Plates Using the Energy Method
Kim, Moon-Young ; Min, Byoung-Cheol ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 411~411
For stability and free vibration analyses of rectangular thin plates with various loading and boundary conditions, an energy method is especially useful in those cases where a rigorous solution of the differential equation is unknown or it is required to find only an approximate value of the critical load and the natural frequency. The strain energy and kinetic energy due to the plate bending and the work done by the in-plane forces are considered in order to apply the Hamilton's principle. The mode shapes for free vibration of beams with various boundary conditions we derived, and the shape functions consistent with the given boundary conditions in the two orthogonal directions are chosen from these displacement functions of beams. The matrix equations for stability and free vibration of rectangular plates are determined from the stationary condition of the total potential energy. Numerical examples are presented and the obtained results are compared with other researchers' results.
Dynamic Tests of Frcition Rubber Bearing for Seismic Isolation
Kim, Young-Suk ; Kim, Hyo-Bum ; Chung, Gil-Young ; Moon, Jang-Soo ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 425~425
Existing base isolators may be effective in reducing the response acceleration in the occurrence of earthquake. However, the large lateral displacement is usually created because of the small stiffness. In this regard, the purpose of this study is to show the reduction of the displacement in the base isolation by improving the damping effects in new isolator. The device, described in this paper, consists of the Coulomb damping from P.T.F.E friction device and the rubber characteristics that aim the additional hysteretic damping and the restoring force by its stiffness. The descriptions presented in this paper are the Coulomb damping characteristics of P.T.F.E. the dynamic characteristics of the laminated rubber part and total dynamic characteristics of the developed device that combined these two characteristics. The test results demonstrate good performance of energy dissipation capability from friction and additional damping. Also, the results show the good performance of restoring capability. Finally, numerical modelings for friction rubber bearing have been presented.
Properties of Reducing Drying Shrinkage by Using Shrinkage Reducing Agent
Lee, Seung-Han ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 435~435
This paper presents the characteristics of drying shrinkage of the cement mortar using a shrinkage reducing agent and a expanding agent. The unrestricted and restrained drying shrinkage strain, the rate of weight loss and strength of the mortar are measured according to age, and also the surface tension measured by changing the consistency of aqueous solution. The experimental results show that the shrinkage reducing agent reduce surface tension considerably and increase the rate of weight loss according to drying of hardened cement mortar. The mechanism of reducing drying shrinkage is assumed to be tile weakening function of surface tension of capillary water in hardened cement mortar. In a experiment for unrestricted drying shrinkage strain, the use of 1.5% of shrinkage reducing agent can reduce the shrinkage reducing rate up to 30% without loss of strength. In restrained drying shrinkage strain test according to JIS, the use of 1.5% of shrinkage reducing agent is effective on the control of 20% of the restrained tension strain rate and the use of 0.45% of expansion agent is effective on the control of 50% of that. In the restrained strain test, the admixtures of shrinkage reducing agent and expanding agent are effective in the prevention of crack as shrinkage reducing effect by shrinkage reducing agent are rised according to the expanding effect by expanding agent.
An Experimental Study on the Reduction in the Flexural Stiffness of Composite Beams under Fatigue Loading
Chang, Sung-Pil ; Shim, Chang-Su ; Youn, Seok-Goo ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 445~445
Five of 1/3 scaled T-shaped composite beams were tested for estimating the reduction in the flexural stiffness subjected to fatigue loads. All the composite beams had the same arrangement of shear studs but different slab thicknesses and reinforcement ratios. The effects of the fatigue behaviors of the shear studs and the growth of the transverse shrinkage cracks in the concrete slab on the flexural stiffness of composite beam were considered. The effects of fatigue losses of the shear studs on the flexural stiffness of composite beam were negligible. The flexural stiffness reduction of the steel-concrete composite beam is mainly due to the transverse cracks in the reinforced concrete slabs. The thickness of concrete slab and the longitudinal reinforcement ratio are primary factor in reducing the fatigue losses of composite beams.
A Study on Load Distribution Effect for Bridge Structures
Chung, Chul-Hun ; Kim, Young-Jin ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 455~455
In most bridge codes, the orthotrophic plate approximations are used in calculating the live load distribution factors. However there may have been serious drawbacks in modeling a bridge as a plate by transforming beams to plate elements. On the other hand, the grillage method uses beam elements to represent a slab in transverse direction, which requires several assumptions regrading the effective flange width for longitudinal elements. adequate modeling width of transverse beam elements, and the dispersion of loads applied to a slab. In the FEM analysis, many assumptions necessary in other methods can be eliminated. Therefore, the finite element method is used in this research to reduce the uncertainties involved in structural modeling procedures. Finally, parametric studies of live load distribution on girder bridges are performed. The parameters affecting load distribution factors include girder spacing, span length, bridge width. number of girders, and number of lanes.
A Study on Strength Characteristics of High Strength Concrete Containing Ground Granulated Blast-Furnace Slag
Moon, Han-Young ; Choi, Yun-Wang ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 463~463
High strength concrete has high heat of hydration and poor workability before setting resulted from significant slump loss due to a large amount of cement content and low water cement ratio.'Results of this study showed that properties of concrete containin GGBF(ground granulated blast-furnace) slag varying fineness, GGBF slag-cement ratio, age and cement content are slightly different from those of conventional high strength concrete. The maximum compressive strength at age of 28 days was
. In addition, compressive strength, tensile strength and elastic modulus of concrete made with GGBF slag 30% replacement cement showed higher value than that of concrete not containing GGBF slag.
Prediction of Defects in a Planestress Body by Nonlinear Optimization of Constitutive Parameters
Shin, Soo-Bong ; Koh, Hyun-Moo ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 473~473
A numerical study on predicting defects in an elastic planestress body is carried out by applying an optimization technique. A response error between the measured and computed displacements is minimized to predict the location and size of the defects in a body A parameterized finite element model is formulated by decomposing the stiffness matrix into constitutive parameters and kernel matrices for each element. A nonlinear constrained optimization problem is solved for optimal constitutive parameters in each finite element of the model. Defects in a planestress body are predicted by the reduction in the constitutive parameters from their baseline values without modifying the topology of the system model for the defect-free state. Measured data relatively sparse with respect to the number of unknown parameters is simulated. An adaptive parameter grouping scheme is applied to locate the defects with a pre-defined finite element model. The proposed method is investigated through simulated examples. The effects of measurement error on the identified results are also investigated through the examples.
Safety Assessment of Large Underground Structures for Earthquake Loading
Chang, Sung-Pil ; Seo, Jeong-Moon ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 483~483
A method for assessing seismic safety and fragility of large underground rock caverns constructed by NATM is proposed. The construction errors and the uncertainties in rock mass property can be taken into account in this method. Load transfer mechanism of unbalanced load within shotcrete is modeled and the analytical method for calculating shotcrete stress and rock bolt shear displacement is suggested. Methods for determining seismic loads for the quasi-static analysis of horizontal underground structure are given. Interaction equations for evaluating safety factors for support system and rock mass are suggested. The applicability of the suggested method is shown through an example of a typical
Life Cycle Cost Analysis of Conventional and Used-Tire Recycled Pavements
Kim, Nak-Seok ; Malpass, G.A. ; Im, Jung-Soon ;
Journal of The Korean Society of Civil Engineers, volume 16, issue 1_4, 1996, Pages 493~493
This paper compares the direct cost of conventional and used-tire recycled pavements through a life cycle cost analysis. The life cycle cost analysis of a pavement is a valuable tool for making economic decisions concerning the use of rubber To compare the pavement with and without rubber the total cost of the pavement was quantified over the analysis period. This total cost includes engineering cost, initial construction cost, maintenance cost, major rehabilitation cost, and user cost. In this study, the new construction Systems 1 through 7 were analyzed using the present worth methods. The costs per mile have been calculated from recent bid average data and analyzed over a 20year analysis period. The life cycle cost analysis results showed that the asphalt-rubber pavement systems with an asphalt treated base was 1.7 to 1.9 times higher than similar conventional pavements for the dry and wet systems, respectively. Also, the life cycle cost of the dry and wet process pavements was 1.4 times higher than similar con ventional systems with aggregate base layers. Among the rubberized pavement systems with an asphalt treated base, the wet system was found to be around 10 percent more costly than the dry process due to the high initial construction cost for the wet system Although asphalt-rubber pavement system does not seem to represent an attractive alternative to conventional systems, it should be strongly noted that the disposal (recycling) of waste tires in pavements certainly has public health and other environmental benefits that may be difficult to measure and quantify.