• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.69-72
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• 2008

Bridge bearings are devices absorbing the displacements of the superstructure. Elastomeric bearings used generally as bridge bearings absorb the displacements of the superstructure using their rubber characteristics. Elastomeric bearings should make sure their shear fatigue performance not to impede the durability of bridge system. In this paper shear fatigue tests were performed and stiffness were measured through the shear fatigue tests. Tests results show the measured stiffness of elastomeric bearings have no specific tendency. This paper found that elastomeric bearings show bad shear performance or fail early if elastomeric bearings are manufactured with a doublefold elastomeric layer.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.117-120
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• 2008

The bridge bearings are devices absorbing the displacements of the superstructure. KS F 4420 relative to the design of elastomeric bearings in Korea allows shear deformation up to 70% of total rubber height. For the elastomeric bearings to fulfill their shear function required in the design, the stability of allowable shear strain of elastomeric bearings relative to the shear failure should be guaranteed. Moreover considering the possibility that elastomeric bearings are applied to the seismic design together with isolation devices, elastomeric bearings is supposed to display higher shear performance. In this paper ultimate shear performance tests were performed. The measured ultimate shear strains were over 200%. Therefore an allowable shear strain provision becomes safe. But elastomeric bearings expected to show their performance in one united body reveled the separation of components near 200% shear strain. These separation in elastomeric bearing can cause unexpected impact or concentrated stress to bridge system considering to application of seismic design. Therefore provision relevant to separation problem is necessary.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.1-6
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• 2002

In order to apply seismic isolators to low-cost buildings, seismic isolators have to be low-cost and light. In this paper fiber reinforced strip form isolator in which the steel plates of conventional rubber bearing were replaced by fiber was proposed. The proposed fiber reinforced strip form isolator was designed, fabricated, cut and subjected to vertical test and horizontal test. Therefore, fiber reinforced strip form isolator was to be shown valid in the view point of fabrication and application to desired size. The horizontal test and vertical test have shown that fiber reinforce strip form isolator could be replaced the rubber isolator. By these results, low-cost and light seismic isolator can be applied to the low-cost building.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.1-8
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• 1999

The bridges for Korea High-Speed Railway(KHSR) under construction are supported with pot bearings on the middle pier and with pad bearings on the side piers, respectively. The dynamic analysis on these bridges due to trains with high speed, however, has been performed neglecting the effects of bearings. The objective of this study is investigation on the dynamic behavior of bridge supported by pad bearings. The effects of pad bearings with various flexibilities on the dynamic responses of bridges are studied. From the results of this study, the effects of elastomeric bearing on the dynamic responses of bridge(especially vertical accelerations) may cause undesirable behaviors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.4
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• pp.681-691
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• 2017

In this research, life cycle inventory database (LCI DB) was developed for elastomeric bearing employing life cycle assessment (LCA) methodology additionally the reliability improvement rate in the evaluation of the environmental load of the bridge was analyzed. As are result of impact assessment by 6 major impact categories, production of elastomeric bearing puts on environmental impact in the order of resource depletion, global warming, photochemical oxidant creation. and among a wide variety of input, steel plates contributes in most of the impact categories. As a result of applying the elastomeric bearing LCI database constructed in this study, the environmental loads increased by 0.53% on average, and the cut-off based on the cost of input materials increased by 11.36%. It is anticipated that it will be possible to improve the credibility and to provide data based on current production technology, such as estimating GHG emissions and evaluating environmental load, by constructing elastomeric bearing LCI DB.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.437-446
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• 2006

Open-steel-plate-girder(OSPG) bridges are one of the most prevalent bridge types among Korean railway bridges. They account for about 40% of all Korean railway bridges. However, the line-type bearings used for OSPG bridges generate several problems with respect to the bridges' dynamic behavior and maintenance. The replacement of the existing bearings with polyurethane disk bearings could be a possible solution to this problem. This type of disk bearing is an elastic bearing using a polyurethane disk. This study estimated the variations in the natural frequency of a bridge when disk bearings were installed and the bridge's dynamic behavior with a running locomotive and running trains. The first natural frequency of the bridge was 3% lower than that of the as-built bridge after the installation of the disk lower, respectively. Also, the second and third frequencies were 7 and 15% lower, respectively. The disk bearings increased the vertical displacement of the bridge, but the pure displacement, excluding the disk deformation, did not vary. The vertical acceleration did not increase when the disk bearing was installed, with trains running. The shear pin in the disk bearing reduced the lateral displacement and the acceleration of the bridge.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.475-485
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• 2008

This paper intends to enhance the reliability and performance of domestic elastomeric bearings through the proposal of directions for the improvement of their stiffness regard to the Korean industrial standard KS F 4420 relative to the evaluation of design/fabrication/quality. Therefore, comparative analysis of the compressive elastic modulus, stiffness measurement method and performance evaluation method of KS F 4420 with those of Eurocode, Japanese bearing manual, and ISO code was performed, and measurement tests on the compressive stiffness and shear stiffness of common elastomeric bearings produced in Korea were conducted. The experimental results reveal that differences of about 20% and 13% occurred respectively for the compressive stiffness and shear stiffness according to the definition adopted for the stiffness. The measured values for the stiffness of the domestic elastomeric bearings were also verified to exhibit large deviation from the formula proposed by KS F 4420. Elastomeric bearings that does not have appropriate compressive stiffness required at the design can result in uneven deflection at supports of bridges and excessive stress in girders. Accordingly, the establishment of compressive elastic modulus formula and performance evaluation criteria fitted to the domestic circumstances through the execution of performance evaluation of bearings presenting diversified shapes and shape factors appears to be necessary for the domestic bearings to meet the performance required in design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.96-106
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• 2014

The increased vibration level of the railway bridge could make significant noise and, also, cause structural damages such as fatigue cracks. Related to these subjects, a spherical elastomeric bridge bearing, which is layered by hemispherical rubber and steel plates, was investigated in terms of its vibration performance. Several different shape factors could be considered by changing the curvature of hemispherical surface and size in rubber and steel plate thicknesses in the manufacturing stage. The performance of the spherical elastomeric bearing for the reduction in vibration was compared with that of the conventional bearing by performing vibration experiments on a scale-downed model. The rubber material characteristics and spherical shape are found to be important parameters in reducing the bridge vibration.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2026-2033
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• 2002

The purpose of this study is to investigate the effect of mechanical properties of the FREI using horizontal stiffness and vertical stiffness by experiments. Two kinds of FREI are designed and fabricated. The steel plates of SREI are replaced with fibers in order to reduce the cost of fabrication and installation. At first, the Nylon fiber is adopted as feasibility study of FREI. The experimental results of Nylon FREI and SREI show that the vertical stiffness of Nylon FREI is lower than SREI, and effective damping is two times higher than SREI. Carbon is adopted, by these rusults, as strong reinforcement than Nylon and full scale of carbon FREI was designed and fabricated. By the experimental test results, it is shown that the vertical stiffness of carbon FREI is three times higher than SREI, and two times higher in effective damping. As a result, the proposed FREI can replace the SREI as a seismic isolator.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.181-187
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• 2011

This paper deals with free vibrations of the Timoshenko beam supported by two elastomeric bearings at two far ends. The ordinary differential equation governing free vibrations of such beam is derived, in which both effects of rotatory inertia and shear deformation are included as the Timoshenko beam theory. Also, boundary conditions of the free end are derived based on the Timoshenko beam theory. The ordinary differential equation is solved by the numerical methods for calculating natural frequencies and mode shapes. Both effects of the rotatory inertia and shear deformation on natural frequencies are extensively discussed. Also, relationships between natural frequencies and slenderness ratio, foundation modulus and bearing length are presented. Typical mode shapes of bending moment and shear force as well as deflection are given in figures which show the positions of maximum amplitudes and nodal points.