• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.349-352
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• 2006

According to current bridge design code cable supported bridges are designed generally against 1000-year-return-period earthquake. Considering its importance, however, it may be desirable to design against 2400-year-return-period earthquake. But the seismic behavior of cable supported bridges under higher seismicity is not investigated fully. In this study, several cable supported bridges were analyzed under higher seismicity and then the response forces in prime members were compared with those analyzed under current design earthquake.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1171-1173
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• 2005

This paper presents a clean lifter design using a magnetic levitation system. Electromagnets are used as a levitation magnet attached to the clean lifter. The lateral forces are generated by the magnets so that non-contacting bearings are implemented. The clean lifter design specifications are suggested and the overall system is described.

• Structural Engineering and Mechanics
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• v.44 no.5
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• pp.611-631
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• 2012

The passive energy dissipation technology has been proven to be reliable and robust for recent practical applications. Various dampers or energy dissipation devices have been widely used in building structures for enhancing their performances during earthquakes, windstorm and other severe loading scenarios. This paper presents a simplified seismic design procedure for retrofitting earthquake-damaged frames with viscous dampers. With the scheme of designing the main frame and the supplemental viscous dampers respectively, the seismic analysis model of damped structure with viscous dampers and braces was studied. The specific analysis process was described and approach to parameter design of energy dissipation components was also proposed. The expected damping forces for damped frame were first obtained based on storey shear forces; and then they were optimized to meet different storey drift requirements. A retrofit project of a RC frame school building damaged in the 2008 Wenchuan earthquake was introduced as a case study. This building was retrofitted by using viscous dampers designed through the simplified design procedure proposed in this paper. Based on the case study, it is concluded that this simplified design procedure can be effectively used to make seismic retrofit design of earthquake-damaged RC frames with viscous dampers, so as to achieve structural performance objectives under different earthquake risk levels.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1215-1240
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• 2015

In this paper, the Theory of Plastic Mechanism Control (TPMC) is applied to the seismic design of dual systems composed by moment-resisting frames and Chevron braced frames. The application of TPMC is aimed at the design of dual systems able to guarantee, under seismic horizontal forces, the development of a collapse mechanism of global type. This design goal is of primary importance in seismic design of structures, because partial failure modes and soft-storey mechanisms have to be absolutely prevented due to the worsening of the energy dissipation capacity of structures and the resulting increase of the probability of failure during severe ground motions. With reference to the examined structural typology, diagonal and beam sections are assumed to be known quantities, because they are, respectively, designed to withstand the whole seismic actions and to withstand vertical loads and the net downward force resulting from the unbalanced axial forces acting in the diagonals. Conversely column sections are designed to assure the yielding of all the beam ends of moment-frames and the yielding and the buckling of tensile and compressed diagonals of the V-Braced part, respectively. In this work, a detailed designed example dealing with the application of TPMC to moment frame-chevron brace dual systems is provided with reference to an eight storey scheme and the design procedure is validated by means of non-linear static analyses aimed to check the actual pattern of yielding. The results of push-over analyses are compared with those obtained for the dual system designed according to Eurocode 8 provisions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.179-194
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• 2017

The segment lining design for shield tunnel is generally carried out by using the beam-spring model and the induced member forces from the model are strongly influenced by the components of the model such as imposed load, coefficient of subgrade reaction, location of segment joint and its stiffness. The structural models and stiffness of its connection part found used in abroad design cases is usually obtained as it is for the domestic design of segment of shield tunnel. Those models and stiffness in existing design cases are conventionally applied to a new tunnel design without any suitability review for the project. In this study, the application method of base components of the model such as the coefficient of subgrade reaction and modelling method to the segment lining design was suggested by carrying out the comparative study of the base elements for the member forces estimation of segment lining of shield tunnel.

• Structural Engineering and Mechanics
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• v.71 no.6
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• pp.643-656
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• 2019

A new seismic design methodology was proposed for precast concrete diaphragms. This methodology adopts seismic design factors applied on top of current diaphragm design forces. These factors are aimed to produce diaphragm design strengths aligned with different seismic performance targets. These factors were established through extensive parametric studies. These studies used a simple evaluation structure with a single-bay rectangular diaphragm. The simple evaluation structure is suitable for establishment of the design factors over comprehensive structural geometry and design parameters. However, the application of the design factors to prototype structures with realistic layouts requires further verification and investigation. This paper presents diaphragm design of several precast concrete parking structures using the new design methodology and verification of the design factor through nonlinear dynamic time history analyses. The seismic behavior and performance of the diaphragm were investigated for the precast concrete parking structures. It was found that the design factor established for the new design methodology is applicable to the realistic precast concrete parking structures.

• Earthquakes and Structures
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• v.20 no.1
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• pp.13-27
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• 2021

A new seismic design methodology has been developed for precast concrete diaphragms. Seismic design factors were used to be applied on top of diaphragm seismic design forces in the current code. These factors, established through extensive parametric studies, align diaphragm design strengths with different seismic performance targets. A simplified evaluation structure with a single-bay plan was used in the parametric studies. This simplified evaluation structure is reasonable and cost-effective as it can comprehensively cover structural geometries and design parameters. However, further verification and investigation are required to apply these design factors to prototype structures with realistic layouts. This paper presents diaphragm design of several precast concrete office buildings using the new design methodology. The applicability of the design factor to the office building was evaluated and verified through nonlinear time history analyses. The seismic behavior and performance of the diaphragm were investigated for the precast concrete office buildings. It was found that the design factor established for the new design methodology is applicable to the realistic precast concrete office buildings.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.1
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• pp.35-48
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• 1995

To develop the optimal design method for the longline type scallop culturing facilities in the open sea numerical calculations and hydraulic model experiments are carried out for the stability and function optimization. Using the results for the motion and tension of the facilities, stable design concepts and effects of motion control system by vertical anchor and resistance discs art discussed. The results of this study that can be applied to the design are as follows: 1) Total external forces by design wave $(H_{1/3}\;=\;6,7\;m,\;T_{1/3}\;=\;12sec)$ at the coastal waters of Jumunjin for unit facility (one main line) are estimated to 5-20 tons, and required anchor weights are 10-40 tons in the case of 2-point mooring system. Though the present facilities are stable to steady currents, but is unstable to the extreme wave condition of return period of 10 years. 2) The dimensions and depth of array systems must be designed considering the ecological environments as well as the physical characteristics including the mooring and holding forces that are proportional to the length and relative depth of main line to wave length, and the number of buoys and nets. 3) Oscillation of the facility is influenced by water particle motion and the weight of hanging net, and is excited at both edge, especially at the lee side. To reduce the motion of the nets, the vertical anchoring system and the resistence disc method are recommended by the experimental results, 4) The damage of rope near the anchor by abrasion should be prevented using the ring-type connection parts or anchor chains.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.34-40
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• 2008

Using the finite element method and Taguchi's design technique, the displacement in vertical direction, von Mises stress, and strain energy of the corrugation damper have been analyzed as functions of the extruded length and the thickness of the corrugation damper, and the upper and lower corner radii of the damper. The optimized profile design elements of a corrugation damper are very important for increasing a strain energy absorption capacity of a helmet structure, which is attacked by impulsive external forces. In this study, the optimized design data based on the Taguchi's method was computed as a corrugation damper length of L = 20 mm, a damper thickness of t = 2 mm, the upper corner radius of $R_1=4\;mm$, and the lower corner radius of $R_2=3\;mm$. The optimized design parameters of a corrugation damper indicated that the thickness and extruded length of a corrugation damper may affect to increase the strain energy, which absorbs the impact forces of the helmet.

• Journal of Platform Technology
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• v.11 no.6
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• pp.47-55
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• 2023

With the goal of ensuring the safety of wheelchair users, this study was conducted using finite element analysis, focusing on the development of a platform that can be used to evaluate safety during the design stage. Safety evaluation criteria for wheelchairs used in vehicles are defined in ANSI/RESNA WC19 and ISO 7176-19. Based on these standards, finite element analysis was performed to assess the sectional forces of each component of the wheelchair and sensitivity analysis was conducted based on the specifications. These results were used to derive equivalent composite loads for the wheelchair's main components, determine the necessary sectional specifications for these main components in the wheelchair design phase, and investigate the process of safety assessment verification. The study showed that member forces vary with changes in the cross-sectional values of the wheelchair frame's main components, with the front and rear lower members, as well as the rear upper and lower members, requiring the highest cross-sectional values for safety design. This study offers a proactive method for evaluating safety in the wheelchair design stage, and in future research, we plan to develop a safety evaluation platform based on these results.