• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1847-1861
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• 2020

A design study was performed to improve the limit aseismic performance (LSP) of a primary heat transport system (PHTS) pump. This pump is part of the primary equipment of a prototype generation IV sodium-cooled fast reactor (PGSFR). The LSP is the maximum allowable seismic load that still ensures structural integrity. To calculate the LSP of the PHTS pump, a structural analysis model of the pump was developed and its dynamic characteristics were obtained by modal analysis. The floor response spectrum (FRS) initiated from a safety shutdown earthquake (SSE), 0.3 g, was applied to the support points of the PHTS pump, and then the seismic induced stresses were calculated. The structural integrity was evaluated according to the ASME code, and the LSP of the PHTS pump was calculated from the evaluation results. Based on the results of the modal analysis and LSP of the PHTS pump, design parameters affecting the LSP were selected. Then, ways to improve the LSP were proposed from sensitivity analysis of the selected design variables.

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.89-100
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• 2006

Recently, lots of lives and properties have been lost because comparatively large magnitude earthquakes were occurred in relatively safe regions and nations. It has been reported that number of earthquakes was increased rapidly in Korea. Hence, recently civil constructions were ensured against risks about earthquake not only large-scale structures but also comparative small-scale structures such as reservoir dams and life line by systematic aseismic design. Therefore, in this study, the seismic stability was ensured to evaluate aseismic performance for major planned reservoir dams in Korea. The seismic response analyses were conducted using SHAKE program on new reservoir dams under short-period, long-period and artificial seismic wave. The liquefaction potential for reservoir dams was assessed by using results from seismic response analysis (simplified assessment method for liquefaction potential). Also, fully coupled analysis--interaction of pore-pressure and soil--was performed to investigate both the development of excess pore water pressure and the characteristic of dynamic shear strain.

• Structural Engineering and Mechanics
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• v.61 no.3
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• pp.419-426
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• 2017

Recently, the transportation of dangerous explosive goods is increasing, which makes vehicle blasting accidents a potential threat for the safety of bridge structures. In addition, blasting accidents happen more easily when earthquake occurs. Excessive dynamic response of bridges under extreme loads may cause local member damage, serviceability issues, or even failure of the whole structure. In this paper, a new explosion-proof and aseismic system is proposed including cable support damping bearing and steel-fiber reinforced concrete based on the existing researches. Then, considering one 40m-span simply supported concrete T-bridge as the prototype, through scale model test and numerical simulation, the dynamic response of the bridge under three conditions including only earthquake, only blast load and the combination of the two extreme loads is obtained and the applicability of this explosion-proof and aseismic system is explored. Results of the study show that this explosion-proof and aseismic system has good adaptability to seism and blast load at different level. The reducing vibration isolation efficiency of cable support damping bearing is pretty high. Increasing cables does not affect the good shock-absorption performance of the original bearing. The new system is good at shock absorption and displacement limitation. It works well in reducing the vertical dynamic response of beam body, and could limit the relative displacement between main girder and capping beam in different orientation so as to solve the problem of beam falling. The study also shows that the enhancement of steel fibers in concrete could significantly improve the blast resistance of main beam. Results of this paper can be used in the process of antiknock design, and provide strong theoretical basis for comprehensive protection and support of girder bridges.

• Structural Engineering and Mechanics
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• v.2 no.1
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• pp.81-94
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• 1994

It is well recognized that structures designed to resist strong ground motions should be able to withstand substantial inelastic deformations. A simple procedure has been developed in this paper to monitor the dynamic earthquake response (time-history analysis) of both steel and concrete multistorey buildings in the inelastic range. The building is treated as a shear beam model with three degrees of freedom per floor. The entire analysis has been programmed to run on a microcomputer and can output time histories of displacements, velocities, accelerations and member internal forces at any desired location. A record of plastic hinge formation and restoration to elastic state is also provided. Such information can be used in aseismic analysis and design of multistorey buildings so as to control the damage and optimize their performance.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.231-238
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• 1997

Many methods have been proposed for achieving optimum performance of structures subjected to earthquake excitation. The conventional approach requires that structures passively resist earthquakes through a combination of strength, deformability, and energy absorption. Base isolation is a technique for mitigating the effects of earthquakes on structures through the introduction of flexibility and energy absorption capability. In this paper, a parametric study of effectiveness of isolation systems with various main structures' properties is carried out through the response spectrum analysis. It is shown that, most base isolators with its longer period and higher damping can significantly reduce the base shear force transmitted to the structures.

• Structural Engineering and Mechanics
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• v.59 no.3
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• pp.387-401
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• 2016

This paper takes a half-through steel truss arch bridge as an example. A seismic analysis is conducted with nonlinear finite element method. Contrast models are established to discuss the effect of simplified method for main girder on the accuracy of the result. The influence of seismic wave direction and wave-passage on seismic behaviors are analysed as well as the superstructure and arch ring interaction which is mostly related with the supported bearings and wind resistant springs. In the end, the application of cable-sliding aseismic devices is discussed to put forward a layout principle. The main conclusions include: (1) The seismic response isn't too distinctive with the simplified method of main girder. Generally speaking, the grillage method is recommended. (2) Under seismic input from different directions, arch foot is usually the mostly dangerous section. (3) Vertical wave input and horizontal wave-passage greatly influence the seismic responses of arch ring, significantly increasing that of midspan. (4) The superstructure interaction has an obvious impact on the seismic performance. Half-through arch bridges with long spandrel columns fixed has a less response than those with short ones fixed. And a large stiffness of wind resistant spring makes the the seismic responses of arch ring larger. (5) A good isolation effectiveness for half-through arch bridge can be achieved by a reasonable arrangement of CSFABs.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.349-356
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• 2000

Strenght and ductility are major factors in the aseismic design of a bridge pier. In spite of good performance in both steel piers have not been used widely due to high cost. But with the filled-in concrete the steel pier have advantages compare to the steel pier only such as improved strength ductility fast construction small section and reasonable cost. In this paper concrete-filled steel piers are tested using quasi-static cyclic lateral load with constant axial load to evaluate the performance. The secondary reinforcement devices such as bolts corner plate and turn buckle are used inside of the piers to improve the ductility with minimum additional cost. Test results shows filled-in concrete and secondary reinforcement devices increase the strength and the ductility of the steel pier.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.320-328
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• 2001

Base Isolation system is an effective design strategy that provides a practical substitute for the seismic design of bridge. In this study, the dynamic tests were performed on two kinds of aseismic bridge bearings : Hydampot (hysteretic damping bearing) and Dynapot . Then, the dynamic analysis was carried out far a bridge using the experimental results to estimate the seismic performance of the bearings. Analysis was performed for four types oi earthquake loadings. The results of the dynamic test and theoretical analysis indicate that the performance of both bridge bearings is appropriate fur the earthquake loading.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.79-89
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• 2000

In this paper, the seismic analysis and the modeling techniques have been introduced for aseismic performances assessment, when seismic isolation bearings are applied on a real bridge. Nonlinear time-history analysis is carried out using finite element analysis program. In this study, EI Centro earthquake(1940, N00W), Mexico earthquake(1985, N90W), and earthquake simulation from modified SIMQKE are used as earthquake ground excitations. The seismic response of seismically isolated bridge is compared with that of a bridge using conventional Pot Bearings, after obtaining the displacements of the deck, the deformations of the piers, shear forces and moments of the bottoms of the piers. The analytical analysis results show that seismic isolation bearing, especially seismic isolation bearings with sliding mechanism, could reduce earthquake forces.

• Earthquakes and Structures
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• v.6 no.3
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• pp.317-334
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• 2014

The work is concerned with an investigation of the advantages stemming from the use of lightweight aggregate concrete in earthquake-resistant reinforced concrete construction. As the aseismic clauses of current codes make no reference to lightweight aggregate concrete beams made of lightweight aggregate concrete but designed in accordance with the code specifications for normal weight aggregate concrete, together with beams made from the latter material, are tested under load mimicking seismic action. The results obtained show that beam behaviour is essentially independent of the design method adopted, with the use of lightweight aggregate concrete being found to slightly improve the post-peak structural behaviour. When considering the significant reduction in deadweight resulting from the use of lightweight aggregate concrete, the results demonstrate that the use of this material will lead to significant savings without compromising the structural performance requirements of current codes.