• Steel and Composite Structures
• /
• 제33권4호
• /
• pp.569-581
• /
• 2019

Corrugated steel plate shear wall (CSPSW) as an innovative lateral load resisting system provides various advantages in comparison with the flat steel plate shear wall, including remarkable in-plane and out-of-plane stiffnesses and stability, greater elastic shear buckling stress, increasing the amount of cumulative dissipated energy and maintaining efficiency even in large story drifts. Employment of low yield point (LYP) steel web plate in steel shear walls can dramatically improve their structural performance and prevent early stage instability of the panels. This paper presents a comprehensive structural performance assessment of corrugated low yield point steel plate shear walls having circular openings located in different positions. Accordingly, following experimental verification of CSPSW finite element models, several trapezoidally horizontal CSPSW (H-CSPSW) models having LYP steel web plates as well as circular openings (for ducts) perforated in various locations have been developed to explore their hysteresis behavior, cumulative dissipated energy, lateral stiffness, and ultimate strength under cyclic loading. Obtained results reveal that the rehabilitation of damaged steel shear walls using corrugated LYP steel web plate can enhance their structural performance. Furthermore, choosing a suitable location for the circular opening regarding the design purpose paves the way for the achievement of the shear wall's optimal performance.

• Computers and Concrete
• /
• 제16권4호
• /
• pp.503-529
• /
• 2015

Traditionally, multi-story buildings are designed to provide stiffer structural support to withstand lateral earthquake loading. Introducing flexible elements at the base of a structure and providing sufficient damping is an alternative way to mitigate seismic hazards. These features can be achieved with a device known as an isolator. This paper covers the design of base isolators for multi-story buildings in medium-risk seismicity regions and evaluates the structural responses of such isolators. The well-known tower building for police personnel built in Dhaka, Bangladesh by the Public Works Department (PWD) has been used as a case study to justify the viability of incorporating base isolators. The objective of this research was to establish a simplified model of the building that can be effectively used for dynamic analysis, to evaluate the structural status, and to suggest an alternative option to handle the lateral seismic load. A finite element model was incorporated to understand the structural responses. Rubber-steel bearing (RSB) isolators such as Lead rubber bearing (LRB) and high damping rubber bearing (HDRB) were used in the model to insert an isolator link element in the structural base. The nonlinearities of rubber-steel bearings were considered in detail. Linear static, linear dynamic, and nonlinear dynamic analyses were performed for both fixed-based (FB) and base isolated (BI) buildings considering the earthquake accelerograms, histories, and response spectra of the geological sites. Both the time-domain and frequency-domain approaches were used for dynamic solutions. The results indicated that for existing multi-story buildings, RSB diminishes the muscular amount of structural response compared to conventional non-isolated structures. The device also allows for higher horizontal displacement and greater structural flexibility. The suggested isolation technique is able to mitigate the structural hazard under even strong earthquake vulnerability.

• 대한조선학회논문집
• /
• 제43권1호
• /
• pp.15-21
• /
• 2006

Recently, the attention to large container ships whose size is greater than 10,000 TEU container ship has been increased due to their increasing demand. The large container ship has twin skegs because of the engine capacity and large beam-draft ratio. In this paper, the maneuvering characteristics of a container ship with twin skegs were investigated through 4DOF(four degree of freedom) HPMM(Horizontal Planar Motion Mechanism) test and computer simulation. A mathematical model for maneuvering motion with 4DOF of twin skegs system was established to include effects of roll motion on the maneuvering motion. And to obtain roll-coupling hydrodynamic coefficients of a container ship, 4DOF HPMM system of MOERI which has a roll moment measurement system was used. HPMM tests were carried out for a 12,000 TEU class container ship with twin skegs at scantling load condition. Using the hydrodynamic coefficients obtained, simulations were made to predict the maneuvering motion. Rudder forces of twin-rudders were measured at the angles of drift and rudder. The neutral rudder angles with drift angles of ship was quite different with those of single skeg ship. So other treatment of flow straightening coefficient $\gamma_R$ was used and the simulation results was compared with general simulation result. The treatment of experimental result at static drift and rudder test was very important to predict the maneuverability of a container ship with twin skegs.

• 한국철도학회논문집
• /
• 제10권5호
• /
• pp.619-625
• /
• 2007

본 논문은 인천국제공항철도에서 운행하고 있는 전동차의 동적특성시험을 수행한 결과이다. 인천국제공항철도의 직통형 전동차는 국내 처음으로 120km/h로 주행한 차량으로 탈선계수를 공차와 만차로 구분하여 측정하였다. 탈선계수측정결과 탈선에 대한 안전성을 판단할 때 가장 기본적인 지표로 사용하는 탈선계수는 공차 때가 만차 때보다 높게 나타났으며, 공차와 만차 모두 0.8 미만이었다. 속도에 따른 탈선계수는 80km/h를 전후한 속도 대역으로 운행하는 구간이 선로상태가 좋지 않은 구간으로서 탈선계수도 증가하는 것으로 나타났다. 횡압은 공차 때에는 2.1톤 미만이었으며, 만차 때에는 2.4톤 미만으로 발생하였다. 인천국제공항철도 전동차가 120km/h 주행에서도 안전함을 탈선계수 실측에 의해 확인하였다. 그러나 본 논문에서 적용된 평가방법의 경우 시험방법이 복잡하고, 측정장치 설치의 어려움이 있으며, 비용이 많이 드는 단점이 있었다. 따라서 측정이 간단한 방법으로 영업운전에서도 차량의 안전성을 확인할 수 있는 방안이 연구되어야 할 것이다.

• Structural Engineering and Mechanics
• /
• 제69권2호
• /
• pp.221-230
• /
• 2019

In this paper, shear behavior of non-persistent joint surrounded in concrete and gypsum layers has been investigated using experimental test and numerical simulation. Two types of mixture were prepared for this study. The first type consists of water and gypsum that were mixed with a ratio of water/gypsum of 0.6. The second type of mixture, water, sand and cement were mixed with a ratio of 27%, 33% and 40% by weight. Shear behavior of a non-persistent joint embedded in these specimens is studied. Physical models consisting of two edge concrete layers with dimensions of 160 mm by 130 mm by 60 mm and one internal gypsum layer with the dimension of 16 mm by 13 mm by 6 mm were made. Two horizontal edge joints were embedded in concrete beams and one angled joint was created in gypsum layer. Several analyses with joints with angles of $0^{\circ}$, $30^{\circ}$, and $60^{\circ}$ degree were conducted. The central fault places in 3 different positions. Along the edge joints, 1.5 cm vertically far from the edge joint face and 3 cm vertically far from the edge joint face. All samples were tested in compression using a universal loading machine and the shear load was induced because of the specimen geometry. Concurrent with the experiments, the extended finite element method (XFEM) was employed to analyze the fracture processes occurring in a non-persistent joint embedded in concrete and gypsum layers using Abaqus, a finite element software platform. The failure pattern of non-persistent cracks (faults) was found to be affected mostly by the central crack and its configuration and the shear strength was found to be related to the failure pattern. Comparison between experimental and corresponding numerical results showed a great agreement. XFEM was found as a capable tool for investigating the fracturing mechanism of rock specimens with non-persistent joint.

• Advances in concrete construction
• /
• 제10권6호
• /
• pp.547-557
• /
• 2020

This paper presents one of the demonstration projects undertaken during the FP7 EU-funded Anagennisi project (Innovative reuse of all tyre components in concrete-2014-2017) on a full-scale (30 m×40 m, thickness: 0.2 m) Steel Fibre Reinforced Concrete (SFRC) slab-on-grade using a blend of manufactured steel fibres (MSF) and Recycled Tyre Steel Fibres (RTSF). The aim of the project was to assess the use of RTSF in everyday construction practice. The Anagennisi partners, Dulex Ltd in collaboration with Gradmont-Gradacac Ltd and University of Zagreb, designed, cast and monitored the long-term shrinkage deformations of the indoor slab-on-grade slab at Gradmont's precast concrete factory in Gradacac, Bosnia and Herzegovina. A hybrid RTSF mix (20 kg/㎥ of MSF+10 kg/㎥ of RTSF) was used to comply with the design criteria which included a maximum load capacity of 20 kN/㎡. The slab was monitored for one year using surveying equipment and visual inspection of cracks. During the monitoring period, the slab exhibited reasonable deformations (a maximum displacement of 3.3 mm for both, horizontal and vertical displacements) whilst after five years in use, the owners did not report any issues and were satisfied with the construction methodology and materials used. This work confirms that RSTF is a viable and sustainable solution for slab-on-grade applications.

• Computers and Concrete
• /
• 제27권2호
• /
• pp.99-109
• /
• 2021

Experimental and discrete element methods were used to investigate the effects of echelon non-persistent joint on the failure behaviour of joint's bridge area under uniaxial compressive test. Concrete samples with dimension of 150 mm×100 mm×50 mm were prepared. Uniaxial compressive strength and tensile strength of concrete were 14 MPa and 1MPa, respectivly. Within the specimen, three echelon non-persistent notches were provided. These joints were distributed on the three diagonal plane. the angle of diagonal plane related to horizontal axis were 15°, 30° and 45°. The angle of joints related to diagonal plane were 30°, 45°, 60°. Totally, 9 different configuration systems were prepared for non-persistent joint. In these configurations, the length of joints were taken as 2 cm. Similar to those for joints configuration systems in the experimental tests, 9 models with different echelon non-persistent joint were prepared in numerical model. The axial load was applied to the model by rate of 0.05 mm/min. the results show that the failure process was mostly governed by both of the non-persistent joint angle and diagonal plane angle. The compressive strengths of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. It was shown that the shear behaviour of discontinuities is related to the number of the induced tensile cracks which are increased by increasing the joint angle. The strength of samples increase by increasing both of the joint angle and diagonal plane angle. The failure pattern and failure strength are similar in both methods i.e. the experimental testing and the numerical simulation methods.

• 한국구조물진단유지관리공학회 논문집
• /
• 제26권5호
• /
• pp.10-19
• /
• 2022

구조물의 비정형성이 풍하중과 지진하중을 받는 구조물의 안전성에 미치는 영향에 대해 검토하였다. 층별 보부재의 불연속성과 O자형 수평비정형성의 관점에서 4가지 유형의 구조물을 선정하여 구조거동을 평가하였다. ACI 318-11 조건에 대해 풍하중 및 지진하중에 의한 구조물의 변위, 휨모멘트, 축력, 비틀림, 층간변위 응답을 검토하였다. 보부재 불연속성을 갖는 구조물의 상부에 갖는 건물이 가장 큰 복원력을 보였으며, O자형 수평비정형 건물은 전도에 대한 저항이 크므로 횡하중에 대해 안전하였다.

• 한국컴퓨터정보학회논문지
• /
• 제27권2호
• /
• pp.9-14
• /
• 2022

본 연구에서는 유연성을 가지는 공기 조형물과 같은 기구물이 사용자가 원하는 자세를 안정적으로 유지하며 이동하기 위한 방안을 제안한다. 이를 수행하기 위해 IMU를 이용한 수평 유지 자세 제어와 PI 알고리즘을 적용하여 주어진 궤적에 따라 주행이 가능한 이동로봇의 구조를 가지는 로봇 시스템을 연구하였다. 본 연구에서 사용된 공기 조형물은 고정된 자세로 얇은 끈을 이용하는 경우가 많다. 다른 방법으로는 무게 중심부에 하중을 실어 자세를 유지며 공기의 압력을 사용하므로 유연성을 가지는 시스템이다. 이러한 구조물은 디지털 센서 기술의 융합과정을 통해 유연한 형태의 구조물과 이동로봇의 결합으로 다양한 성과를 얻을 수 있을 것으로 기대한다. 본 연구는 로봇의 한 분야인 AGV(무인 반송차)의 주행 기술과 다양한 센서를 응용한 기술들을 융합하여 자세제어를 수행하였다. 검증은 공인인증시험을 통해 주어진 성능 평가를 수행하였으며 실험을 통해 그 타당성을 검증하였다.

• 한국지반공학회논문집
• /
• 제26권11호
• /
• pp.29-38
• /
• 2010

강관합성말뚝은 외부 강관의 합성 구속효과에 의해 말뚝강도가 커지고, 연성파괴 거동이 발생한다. 본 연구에서는 해상 지반에 근입된 무리말뚝에 대하여 말뚝재료의 항복거동 및 지반의 탄소성 거동을 함께 고려할 수 있는 3차원 수치해석을 수행하여 하중-변위 거동 및 강관합성말뚝의 보강효과를 분석하였다. 이를 위하여 강관, 콘크리트, 강관합성말뚝에 대하여 각각 말뚝간격, 말뚝직경 그리고 재하방향을 달리한 변수연구를 수행하였다. 그 결과 수직방향지지력의 경우 강관합성말뚝은 강관말뚝과 비교하여 평균 90% 큰 것으로 나타났고, 콘크리트 말뚝에 대하여는 평균적으로 동일하게 나타났다. 그러고 허용변위 기준에서의 수평방향 지지력의 경우 강관합성말뚝은 강관말뚝보다 평균 50%, 콘크리트 말뚝보다 평균 22% 더 큰 것으로 나타났다.