• 한국전산구조공학회논문집
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• 제22권2호
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• pp.181-187
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• 2009

내진 설계기준이 도입된 이후, 신설교량에 대한 내진 설계의 시행은 물론 기존교량의 내진 성능 검토에 의한 내진 성능 확보가 요구되고 있다. 기존교량의 내진 성능 확보 또한 내진 설계의 기본개념에 따라 붕괴방지수준을 만족하여야 하며, 확보방안으로는 교량의 중요도와 형식에 따라 보강규모가 다른 여러 가지 방안이 제시되어야 한다. 현재 일반교량의 경우 받침의 교체, 교각의 보강 및 전단키 설치 등의 보강방안이 내진 성능 향상 및 확보 방안으로 가장 많이 연구, 적용되고 있는 상황이다. 이 연구에서는 내진 설계가 수행되지 않은 일반적인 기존 교량은 해석대상교량으로 선정하고, 붕괴방지 수준을 만족하기 위해 연성파괴메카니즘을 확보하도록 기존교량의 설계변경을 수행하고 내진 성능을 검토하였다. 기존교량의 경우, 하부구조 교각기둥의 설계단면 결정 및 상/하부구조 연결부 받침의 기능변경 등 교량시스템의 재 설계에 의해 내진 성능을 확보할 수 있다는 것을 제시하였다.

• 한국지진공학회논문집
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• 제21권5호
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• pp.245-254
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• 2017

The building which are essential for disaster recovery is classified as a special seismic use group. Especially, achievement of seismic performance is very important for the hospital, so the hospital should be able to maintain its function during and right after an earthquake without significant damage on both structural and non-structural elements. Therefore, this study aimed at checking the seismic performance of a hospital building, but which was limited to structural elements. For the goal, a plan with a configuration of general hospitals in Korea was selected and designed by two different seismic-force-resisting systems. In analytical modeling, the shear behavior of the wall was represented by three inelastic properties as well as elastic. Nonlinear dynamic analyses were conducted to evaluate the performance of structural members. The result showed that the performance of shear walls in the hospital buildings was not satisfied regardless of the seismic-force-resisting systems, while the demands on the beams and columns did not exceed the capacities. This is the result of only considering the shear of the wall as the force-controlled action. When the shear of the wall was modeled as inelastic, the walls were yielded in shear, and as the result, the demands for frames were increased. However, the increase did not exceed the capacities of the frames members. Consequently, since the performance of walls is significant to determine the seismic performance of a hospital building, it will be essential to establish a definite method of modeling shear behavior of walls and judging their performance.

• Earthquakes and Structures
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• 제9권3호
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• pp.563-576
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• 2015

Over the past few decades, seismic retrofitting of structural systems has been significantly improved by the adoption of various methods such as FRP composite wraps, base isolation systems, and passive/active damper control systems. In parallel with this trend, probabilistic risk assessment (PRA) for structural and nonstructural components has become necessary for risk mitigation and the achievement of reliable designs in performance-based earthquake engineering. The primary objective of the present study was to evaluate the effect on piping fragility at T-joints due to seismic retrofitting of structural systems with passive energy-dissipation devices (i.e., linear viscous dampers). Three mid-rise building types were considered: without any seismic retrofitting; with distributed damper systems; with optimal placement of dampers. The results showed that the probability of piping system failure was considerably reduced in a Multi Degree of Freedom (MDOF) building retrofitted with optimal passive damper systems at lower floor levels. This effect of damper systems on piping fragility became insignificant as the floor level increased.

• Structural Engineering and Mechanics
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• 제73권1호
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• pp.53-64
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• 2020

In different high seismic regions around the world, many non-ductile existing reinforced concrete frame buildings, built without adequate seismic detailing requirements, have been damaged or collapsed after past earthquakes. The assessment and the retrofit of these non-ductile concrete structures is crucial theme of research for all the scientific community of engineers. In particular, a careful assessment of the existing building is fundamental for understanding the failure mechanisms that govern the collapse of the structure or the achievement of the recommended limit states. Based on the seismic assessment, the best retrofit strategy can be designed and applied to the structure. A school building located in Avellino province (Italy) is the case study. The analysis of seismic vulnerability carried out on the mentioned building has highlighted deficiencies in both static and seismic load conditions. The retrofit of the building has been designed based on different retrofit options in order to show the real retrofit design developed from the engineers to achieve the seismic safety of the building. The retrofit costs associated to structural operations are calculated for each case and have been summed up to the costs of the in situ tests. The paper shows a real retrofit design case study in which the best solution is chosen based on the results in terms of structural performance and cost among the different retrofit options.

• Earthquakes and Structures
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• 제11권2호
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• pp.195-215
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• 2016

Rehabilitation of historical unreinforced masonry (URM) buildings is a priority in many parts of the world, since those buildings are a living part of history and a testament of human achievement of the era of their construction. Many of these buildings are still operational; comprising brittle materials with no reinforcements, with spatially distributed mass and stiffness, they are not encompassed by current seismic assessment procedures that have been developed for other structural types. To facilitate the difficult task of selecting a proper rehabilitation strategy - often restricted by international treaties for non-invasiveness and reversibility of the intervention - and given the practical requirements for the buildings' intended reuse, this paper presents a practical procedure for assessment of seismic demands of URM buildings - mainly historical constructions that lack a well-defined diaphragm action. A key ingredient of the method is approximation of the spatial shape of lateral translation, ${\Phi}$, that the building assumes when subjected to a uniform field of lateral acceleration. Using ${\Phi}$ as a 3-D shape function, the dynamic response of the system is evaluated, using the concepts of SDOF approximation of continuous systems. This enables determination of the envelope of the developed deformations and the tendency for deformation and damage localization throughout the examined building for a given design earthquake scenario. Deformation demands are specified in terms of relative drift ratios referring to the in-plane and the out-of-plane seismic response of the building's structural elements. Drift ratio demands are compared with drift capacities associated with predefined performance limits. The accuracy of the introduced procedure is evaluated through (a) comparison of the response profiles with those obtained from detailed time-history dynamic analysis using a suite of ten strong ground motion records, five of which with near-field characteristics, and (b) evaluation of the performance assessment results with observations reported in reconnaissance reports of the field performance of two neoclassical torsionally-sensitive historical buildings, located in Thessaloniki, Greece, which survived a major earthquake in the past.

• 한국강구조학회 논문집
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• 제25권3호
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• pp.255-265
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• 2013

본 연구는 박스형 철골조 유닛 모듈러를 이용하여 고층으로 적층할 수 있는 공업화된 구조시스템을 개발하고자 하는 것이다. 이러한 목표를 달성하기 위해 효율적인 유닛 모듈러 건축시스템의 실용화를 위한 조인트의 상세 개발과 내진성능 확보기술에 대해 기본적인 실험 및 이론해석 연구가 필요하다. 본 연구에서는 고층형 유닛 모듈러 골조를 구성하는 중요 요소인 조인트의 2가지 접합 상세를 도출하였으며, 도출된 조인트에 대한 구조 성능을 실험적으로 평가하였다. 새롭게 개발된 유닛 모듈러 기둥-보 조인트에 대한 실험결과, 6.0T 기둥 및 연결구의 두께를 확보한 조인트는 강도 및 내진 성능의 확보에 있어서 조인트의 소성회전각의 유지가 가능한 것으로 나타났으며 응력이 집중되는 부근에서의 보강을 고려하면 충분히 적용 가능하리라 판단된다.

• 한국지진공학회논문집
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• 제14권2호
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• pp.37-47
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• 2010

RC교량이 내진성능을 확보하기 위해서는 교각의 연성도가 목표연성도에 도달하기 전에 발생하는 전단파괴가 방지되어야 한다. 이를 위해서는 신뢰성 있는 전단강도 평가식이 요구된다. 횡하중을 받는 RC기둥의 전단강도는 변위연성도의 증가에 따라 감소 하는 특성을 나타낸다. 다수의 연구자에 의해 전단강도 식이 제안되어 있으나 변위연성도가 작은 구역에서의 초기전단강도와 연성도 증가에 따른 전단강도의 감소율에서 많은 차이를 보이고 있다. 본 연구에서는 저자들이 제안한 초기전단강도를 기본으로 하여 다른 연구자에 의해서 수행된 많은 기둥실험 결과를 분석하여 변위연성도를 고려한 새로운 전단강도 평가식을 제안하였다, 제안된 평가식은 다른 평가식과의 비교를 통해 정확도가 크게 개선된 것을 확인하였다.