• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.105-113
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• 2000

Seismic behavior of 3-dimensional setback structures showing abrupt reductions of the floor size within the structure height and the effect of in-plane deformations of floor slabs on the seismic behavior of those structures are investigated. To find out general seismic behavior of 3-dimensional setback structures two parameters, level of setback(L/sub s/) and degree of setback(R/sub s/) are used. Analysis results obtained from forty eight setback structures show that a sudden change in story shear near setback level is occurred for irregular setback structures. The effect of in-plane deformation of floor slabs on the seismic behavior of setback structures is greatly influenced by the arrangement of lateral load resisting elements and it is more pronounced for frame-shear wall system showing large difference in stiffness among the lateral load resisting elements. The in-plane deformation of floor slabs results in reduced base shear, especially for FW-type structures with L/sub s/=1.0. Also, it brings about reduced story shear for the lateral load resisting element with shear wall and increase in story shear lot the lateral load resisting element without shear wall. The in-plane deformation of floor slabs at the base portion and/or tower portion due to difference in stiffness among the lateral load resisting elements brings about increment of floor displacements at all floor level.

• Journal of Korean Association for Spatial Structures
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• v.16 no.2
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• pp.79-88
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• 2016

Modular buildings are constructed by assembling modular units which are prefabricated in a factory and delivered to the site. However, due to a problem of noise between floors, concrete slab is usually poured at the top or bottom level of a modular unit in Korea. This greatly increases the weight of buildings, but designing vertical members of modular units to resist overall gravity loads is very inefficient. In this study, considering domestic building construction practices, feasible structural systems for tall modular buildings are proposed in which separate steel frames and reinforced concrete core walls are designed to resist gravity and lateral loads. To verify performance, a three-dimensional structural analysis has been performed with two types of prototype buildings, i.e., a residential building and a hotel. From the results, wind-induced lateral displacements and seismic story drifts are examined and compared with their limit values. Between the two kinds of buildings, the efficiency of the proposed system is also evaluated through a comparison of the weight of structural components. Finally, the effect of a floor diaphragm on the overall behavior is analyzed and discussed.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.597-603
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• 2011

Objective: The objective of this study was to compare one-hand and two-hands lifting activity in terms of biomechanical stress for the range of lifting heights from 10cm above floor level to knuckle height. Background: Even though two-hands lifting activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting are also very common at the industrial site and forestry and farming. Method: Eight male subjects were asked to perform lifting tasks using both a one-handed as well as a two-handed lifting technique. Trunk muscle electromyographic activity was recorded while the subjects performed the lifting tasks. This information was used as input to an EMG-assisted free-dynamic biomechanical model that predicted spinal loading in three dimensions. Results: It was shown that for the left-hand lifting tasks, the values of moment, lateral shear force, A-P shear force, and compressive force were increased by the average 43%, as the workload was increased twice from 7.5kg to 15.0kg. For the right-hand lifting task, these were increased by the average 34%. For the two-hands lifting tasks, these were increased by the average 25%. The lateral shear forces at L5/S1 of one-hand lifting tasks, notwithstanding the half of the workload of two-hands lifting tasks, were very high in the 300~317% of the one of two-hands lifting tasks. The moments at L5/S1 of one-hand lifting tasks were 126~166% of the one of two-hands lifting tasks. Conclusion: It is concluded that the effect of workload for one-hand lifting is greater than two-hands lifting. It can also be concluded that asymmetrical effect of one-hand lifting is much greater than workload effect. Application: The results of this study can be used to provide guidelines of recommended safe weights for tasks involved in one-hand lifting activity.

• Journal of the Ergonomics Society of Korea
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• v.32 no.5
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• pp.413-420
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• 2013

Objective: The objective of this study was to compare one-hand and two-hands lowering activity in terms of biomechanical stress for the range of lowering heights from knuckle height to 10cm above floor level. Background: Even though two-hands lifting/lowering activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting/lowering are also very common at the industrial site and forestry and farming. Method: Eight male subjects were asked to perform lowering tasks using both a one-handed as well as a two-handed lowering technique. Trunk muscle electromyographic activity was recorded while the subjects performed the lowering tasks. This information was used as input to an EMG-assisted free-dynamic biomechanical model that predicted spinal loading in three dimensions. Results: It was shown that for the left-hand lowering tasks, the values of moment, lateral shear force, A-P shear force, and compressive force were increased by the average 6%, as the workload was increased twice from 7.5kg to 15kg. For the right-hand lowering task, these were increased by the average 17%. For the two-hands lowering tasks, these were increased by the average 14%. Conclusion: Even though the effect of workload on the biomechanical stress for both one-hand and two-hands lowering tasks is not so significant for the workload less than 15kg, it can be claimed that the biomechanical stress for one-hand lowering is greater than for two-hands lowering tasks. Therefore, it can be concluded that asymmetrical lowering posture would give greater influence on the biomechanical stress than the workload effect for one-hand lowering activity. Application: The result of this study may be used to provide guidelines of recommended safe weights for tasks involved in one-hand lowering activity.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.865-872
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• 2006

Recently, many apartment buildings in the shear wall system often has pilotis in the lower story to meet the architectural needs. If the lateral force resisting system consists of shear walls supported by columns and beams. the discontinuity at the lowest level with pilotis results in the vertical irregularity with strength and stiffness. So, there are needs to be considered tile analysis and design about column and beam bellow shear walls and the behavior and stress condition of structure by stiffness change being generated at shear walls. The purpose of this paper is to investigate the behavior of shear wall structures with pilotis using the floors modeled as rigid diaphragm or semi rigid diaphragm. Through analyses, after estimating values of the story drift, natural period, stress condition of shear walls and the forces of column, we inferred how the behavior of shear wall structures with pilotis was influenced by the floor stiffness.

• Computers and Concrete
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• v.21 no.5
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• pp.495-504
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• 2018

The possibility of earthquakes in vulnerable regions indicates that efficient technique is required for seismic protection of buildings. During the recent decades, the concept is moving towards the insertion of base isolation on seismic prone buildings. So, investigation of structural behavior is a burning topic for buildings to be isolated in base level by bearing device. This study deals with the incorporation of base isolation system and focuses the changes of structural responses for different types of Lead Rubber Bearing (LRB) isolators. A number of sixteen model buildings have been simulated selecting twelve types of bearing systems as well as conventional fixed-base (FB) scheme. The superstructures of the high-rise buildings are represented by finite element assemblage adopting multi-degree of freedoms. Static and dynamic analyses are carried out for FB and base isolated (BI) buildings. The dynamic analysis in finite element package has been performed by the nonlinear time history analysis (THA) based on the site-specific seismic excitation and compared employing eminent earthquakes. The influence of the model type and the alteration in superstructure behavior of the isolated buildings have been duly assessed. The results of the 3D multistory structures show that the lateral forces, displacement, inertia and story accelerations of the superstructure of the seismic prone buildings are significantly reduced due to bearing insertion. The nonlinear dynamic analysis shows 12 to 40% lessening in base shear when LRB is incorporated leading to substantial allowance of horizontal displacement. It is revealed that the LRB isolators might be potential options to diminish the respective floor accelerations, inertia, displacements and base shear whatever the condition coincides. The isolators with lower force intercept but higher isolation period is found to be better for decreasing base shear, floor acceleration and inertia force leading to reduction of structural and non-structural damage. However, LRB with lower isolator period seems to be more effective in dropping displacement at bearing interface aimed at reducing horizontal shift of building structure.

• International Journal of Concrete Structures and Materials
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• v.18 no.1E
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• pp.55-61
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• 2006

RC shear walls are frequently used as lateral force-resisting system in building construction because they have sufficient stiffness and strength against damage and collapse. If RC shear walls are properly designed and proportioned, these walls can also behave as ductile flexural members like cantilevered beams. To achieve this goal, the designer should provide adequate strength and deformation capacity of shear walls corresponding to the anticipated deformation level. In this study, the level of demands for deformation of shear walls was investigated using a displacement-based design approach. Also, deformation capacities of shear walls are evaluated through laboratory tests of shear walls with specific transverse confinement widely used in Korea. Four full-scale wall specimens with different wall boundary details and cross-sections were constructed for the experiment. The displacement-based design approach could be used to determine the deformation demands and capacities depending on the aspect ratio, ratio of wall area to floor plan area, flexural reinforcement ratio, and axial load ratio. Also, the specific boundary detailing for shear wall can be applied to enhance the deformation capacity of the shear wall.

• Structural Engineering and Mechanics
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• v.32 no.5
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• pp.587-608
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• 2009

Modern earthquake-resistant design aims to isolate architectural precast concrete panels from the structural system so as to reduce the interaction with the supporting structure and hence minimize damage. The present study seeks to maximize the cladding-structure interaction by developing an energy-dissipating cladding system (EDCS) that is capable of functioning both as a structural brace, as well as a source of energy dissipation. The EDCS is designed to provide added stiffness and damping to buildings with steel moment resisting frames with the goal of favorably modifying the building response to earthquake-induced forces without demanding any inelastic action and ductility from the basic lateral force resisting system. Because many modern building facades typically have continuous and large openings on top of the precast cladding panels at each floor level for window system, the present study focuses on spandrel type precast concrete cladding panel. The preliminary design of the EDCS was based on existing guidelines and research data on architectural precast concrete cladding and supplemental energy dissipation devices. For the component-level study, the preliminary design was validated and further refined based on the results of nonlinear finite element analyses. The stiffness and strength characteristics of the EDCS were established from a series of nonlinear finite element analyses and are discussed in detail in this paper.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.37-44
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• 2023

In the case of a school building, even though it is a regular structure in terms of plan shape, if the masonry infill wall acts as a lateral load resisting element, it can be determined as a torsionally irregular building. As a result, the strength and ductility of the structure are reduced, which may cause additional earthquake damage to the structure. Therefore, in this study, a structure similar to a school building with torsional irregularity was selected as an example structure and the damping performance of the PC-BRB was analyzed by adjusting the eccentricity according to the amount of masonry infilled wall. As a result of nonlinear dynamic analysis after seismic reinforcement, the torsional irregularity of each floor was reduced compared to before reinforcement, and the beams and column members of the collapse level satisfied the performance level due to the reduction of shear force and the reinforcement of stiffness. The energy dissipation of PC-BRB was similar in the REC-10 ~ REC-20 analytical models with an eccentricity of 20% or less. REC-25 with an eccentricity of 25% was the largest, and it is judged that it is effective to combine and apply PC-BRB when it has an eccentricity of 25% or more to control the torsional behavior.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5176-5183
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• 2013

In general, Korean Lightweight Concrete used Heat insulating material for building and filler for civil construction, backfill material for tunnel, office floor fillers, lightweight blocks and so on. These expand the range of use ALC(autoclaved lightweight concrete) on the soft-ground at regular intervals during road construction by installing piles used as substrates for the process is under study. In this study, behavior characteristics on the soft-ground of pavement analysis was used to test the geo-Centrifuge. Prototype pavement reduced to 1/30 slab form of the composition as kaolinite model tests were conducted in the soft ground. Pile Arrangement (having 36 component pile with an array of $3{\times}12$) was used to group of piles. Tests of gravity 30 level the centrifugal force acting Light-weight pavement models. Based on the Prototype pavement of the behavior characteristics of pavement behavior characteristics were estimated. FMA analysis of the 10 times as big 39.4kg (actual load 35 ton) of the lateral load is applied to the case 7.8mm (actual behavior 23.4mm) behavior was fine.