• Journal of Korean Association for Spatial Structures
• /
• v.23 no.4
• /
• pp.43-50
• /
• 2023

This study aims to assess the seismic performance of retrofitted reinforced concrete columns using a Replaceable Steel Brace (RSB) system, subjected to combined axial, lateral, and torsional loadings. Through experimental testing, one non-retrofitted concrete column specimen and two retrofitted specimens with variable sliding slot lengths were subjected to eccentric lateral loads to simulate realistic seismic loading. The retrofitted specimens with RSBs exhibited enhanced resistance against shear cracking, effective torsional resistance, and demonstrated the feasibility of easy replacement. The RSB system substantially improved seismic performance, achieving approximately 1.7 times higher load capacity and 3.5 times greater energy dissipation compared to non-retrofitted column, thus validating its efficacy under combined loading conditions.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.842-847
• /
• 2004

This study presents the minimum spring stiffness of resilient track pad considering the safety of running train. A nonlinear static 3-D finite element is used for the modeling of railway superstructure, especially for the reflection of nonlinear resistance of rail fastening system. Moreover, ballast is considered as an elastic foundation. As the input load, eccentric wheel and lateral force are used and they are derived from ' Lateral-force/Wheel-load Estimation Equations '. Analysis results are compared with following two values : allowable lateral displacement of rail head (derived from the geometrical derailment evaluation of wheel/rail) and operation standard value (derived from the field test results of track).

• Journal of the Korean Society of Safety
• /
• v.37 no.4
• /
• pp.101-112
• /
• 2022

Expanding urbanization practices result in high numbers of buildings being developed in city centers. This high building concentration leads to an increased fire risk, resulting in higher casualty rates and increased economic damages compared to fires in the past. The purpose of this study was to analyze the structural behavior of fire-damaged reinforced concrete buildings using analytical methods and to suggest methods of improving fire resistance in the event of a fire. Damage levels were measured using commercial software to apply the finite element method, ABAQUS, and MIDAS GEN to the dataset. Load-deflection curves were calculated using the effective area and moment of inertia of the fire-damaged columns provided by ABAQUS. The results of this analysis indicate that fire-damaged beams with experience greater deflection from indoor fires than they will from outdoor fires. Fires that occurred on the middle floors were more dangerous than those occurring on higher floors, and eccentrically loaded columns experienced more damage than axially loaded columns. The results indicate that these methods accurately predict structural behaviors of fire damaged concrete columns by considering fire exposure area and eccentric loading.

• Structural Engineering and Mechanics
• /
• v.76 no.4
• /
• pp.541-550
• /
• 2020

As a new type of concrete material, basic magnesium sulfate cement concrete (BMSC) has the advantages, such as early strength, high strength, good toughness and crack resistance. However, it is unclear about the degradation of the mechanical properties of BMSC columns, which is exposed to the natural environment for several years. In order to apply this new concrete to practical engineering, six large-eccentricity compressive columns of BMSC were studied. The mechanical properties such as the crack propagation, failure morphology, lateral displacement and bearing capacity of BMSC column were studied. The results show that the degradation rate of ultimate load of BMSC column is from 6% to 7%. The degradation rate of the stiffness of the column is from 6% to 13%. With the increase of compressive strength of BMSC, the axial displacement and lateral displacement are gradually reduced. The calculation model of bearing capacity of the BMSC column under the large eccentric compression is proposed. This paper provides a reference for the application of BMSC columns in the civil engineering.

• Steel and Composite Structures
• /
• v.43 no.4
• /
• pp.483-500
• /
• 2022

Cold-formed steel wall panels sheathed with gypsum plasterboard have shown superior thermal and structural performance in fire. Recent damage caused by fire events in Australia has increased the need for accurate fire resistance ratings of wall systems used in low- and mid-rise construction. Past fire research has mostly focused on light gauge steel framed (LSF) walls under uniform axial compression and LSF floors under pure bending. However, in reality, LSF wall studs may be subject to both compression and bending actions due to eccentric loading at the wall to-roof or wall-to-floor connections. In order to investigate the fire resistance of LSF walls under the effects of these loading eccentricities, four full-scale standard fire tests were conducted on 3 m × 3 m LSF wall specimens lined with two 16 mm gypsum plasterboards under different combinations of axial compression and lateral load ratios. The findings show that the loading eccentricity can adversely affect the fire resistance level of the LSF wall depending on the magnitude of the eccentricity, the resultant compressive stresses in the hot and cold flanges of the wall studs caused by combined loading and the temperatures of the hot and cold flanges of the studs. Structural fire designers should consider the effects of loading eccentricity in the design of LSF walls to eliminate their potential failures in fire.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.9 no.4
• /
• pp.309-317
• /
• 2015

In this paper, we proposed the standard test specification for safety and function of hiking stick for the elderly. We have concluded nine factors representing specification of hiking stick through analysis of hiking patents and research papers, products survey of business market, case studies for damaged hiking stick and expert surveys. To test the factors, we designed three different kinds of apparatus to examine twist resistance, stick and tip durability and stick straightness. The sample of hiking sticks purchased from market based on Naver sales ranking top to fifteenth. As a result, we concluded six-standard test specification based on eccentric load, adjustable parts load, hand strap load, basket load, tip load and pull load of hiking stick.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.148-151
• /
• 2011

현재 방폭설계 관련 설계지침은 기둥제거시나리오를 이용한 대체하중경로법을 주로 적용하고 있지만, 실제로 폭발이 발생하였을 때 기둥의 완전한 파괴가 일어나지 않을 경우 이 방식을 적용하는 것은 적합하지 않다. 따라서 본 논문에서는 비선형 동적 해석 프로그램인 AUTODYN을 이용해 편심하중을 받는 철근 콘크리트 기둥의 잔존 폭발 저항 성능을 평가하는 방식을 제안하였다. 해석결과를 비교해보면 TNT양과 축하중이 클수록 철근콘크리트 기둥의 잔존 폭발 저항 성능이 감소되었다. 이것은 폭발이 발생하기전의 기둥의 편심하중에 의한 응력상태에 따라 폭발 저항 성능이 달라짐을 알 수 있다.

• Steel and Composite Structures
• /
• v.10 no.2
• /
• pp.109-128
• /
• 2010

The expediency of using tubular composite steel and concrete columns of annular cross-sections in construction is discussed. The new type space framework with tubular composite columns of multi-storey buildings and its rigid beam-column joints are demonstrated. The features of interaction between the circular steel tube and spun concrete stress-strain states during the concentrical and eccentrical loading of tubular composite members are considered. The modeling of the bearing capacity of beam-columns of composite annular cross-sections is based on the concepts of bending with a concentrical force and compression with a bending moment. The comparison of modeling results for the composite cross-sections of beam-columns is analysed. The expediency of using these concepts for the limit state verification of beam-columns in the methods of the partial safety factors design (PSFD) legitimated in Europe and the load and resistance factors design (LRFD) used in other countries is presented and illustrated by a numerical example.

• Journal of Korean Association for Spatial Structures
• /
• v.17 no.2
• /
• pp.43-51
• /
• 2017

The demand for skyscrapers is increasing worldwide. Until now, various lateral resistance structures have been used for lateral displacement control of high-rise buildings. An outrigger damper system has been introduced recently to improve lateral dynamic response control performance further. However, a study of outrigger damper system is yet to be sufficiently investigated. In this study, time history analysis was performed to investigate the control performance of an outrigger damper system of high-rise building under eccentric loading. To do this, an actual scale 3-dimensional tall building model with an outrigger damper system was prepared. The control performance of the outrigger damper system was evaluated by varying stiffness and damping values. On the top floor torsional angle response to the earthquake load, was greatly affected by damping value. And the displacement response was affected greatly by the stiffness value and damping value of damper system. In conclusion, it is necessary to select the proper damping and stiffness values of the outrigger damper system.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.149-152
• /
• 2008

In structural design provision, maximum punching shear stress of slabs is prescribed as combined stress of direct shear occurred by balanced gravity load and eccentric shear occurred by unbalanced moment. This means that the effect of unbalanced moment is considered to decide the punching shear stress. However, from the resistance capacity standpoint, the effect of unbalanced moment strength is not considered for deciding punching shear strength. For this problem, a model to show unbalanced moment-punching shear interrelation was proposed. In the model, the relation between load effect and resistance capacity in unbalanced moment-punching shear was two-dimensionally expressed. Using the interrelation model, a method how unbalanced moment strength should be considered to decide the punching shear strength was proposed. Additionally, a effective width enlargement factor for deciding the unbalanced moment strength of flat plates with shear reinforcements was proposed. The interrelation model proposed in this paper is very effective for the design because not only punching shear and unbalanced moment strengths but also failure modes of flat plates can be accurately predicted.