• Structural Engineering and Mechanics
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• 제61권5호
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• pp.663-674
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• 2017

The determination of the fundamental period of vibration of a structure is essential to earthquake design. Current codes provide formulas for the approximate estimation of the fundamental period of earthquake-resistant building systems. These formulas are dependent only on the height of the structure or number of storeys without taking into account the presence of infill walls into the structure, despite the fact that infill walls increase the stiffness and mass of the structure leading to significant changes in the fundamental period. Furthermore, such a formulation is overly conservative and unable to account for structures with geometric irregularities. In this study, which comprises the companion paper of previous published research by the authors, the effect of the vertical geometric irregularities on the fundamental periods of masonry infilled structures has been investigated, through a large set of infilled frame structure cases. Based on these results, an attempt to quantify the reduction of the fundamental period due to the vertical geometric irregularities has been made through a proposal of properly reduction factor.

• 한국지진공학회논문집
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• 제27권2호
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• pp.91-99
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• 2023

Structural vibration induced by earthquake hazards is one of the most significant concerns in structure performance-based design. Structural hazards evoked from seismic events must be properly identified to make buildings resilient enough to withstand extreme earthquake loadings. To investigate the effects of combined earthquake-resistant systems, shear walls and five types of dampers are incorporated in nineteen structural models by altering their arrangements. All the building models were developed as per ACI 318-14 and ASCE 7-16. Seismic fragility curves were developed from the incremental dynamic analyses (IDA) performed by using seven sets of ground motions, and eventually, by following FEMA P695 provisions, the collapse margin ratio (CMR) was computed from the collapse curves. It is evident from the results that the seismic performance of the proposed combined shear wall-damper system is significantly better than the models equipped with shear walls only. The scrutinized dual seismic resisting system is expected to be applied practically to ensure a multi-level shield for tall structures in high seismic risk zones.

• 한국지진공학회논문집
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• 제5권4호
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• pp.67-74
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• 2001

지진에 대한 구조물의 건전도는 내진설계에 의하여 많이 개선된 반면, 구조물 내부의 설비 및 중요 장비등에 대한 안정성은 최근에 관심을 가지게 되었다. 특히 국보급 문화재나 소장품은 그 가치에 비하여 지진에 대한 안전성이 고려되지 않은 것은 사실이다. 본 연구에서는 지진에 의하여 발생할 수 있는 내부 기기 및 문화재의 전도, 낙하를 방지하기 위한 면진 시스템을 개발하여, 본 장치에 대한 면진성능을 진동대 실험을 통하여 검증하였다. 본 면진 테이블은 전시물의 하부에 설치되어, 바닥판의 진동이 전시대에 전달되는 것을 차단하는 격리시스템이다. 면진성능시험 결과, 면진성능이 80-90%이며 면진테이블의 최대 스트로트내에서 안정적으로 거동하는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제32권5호
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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.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.148-156
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• 2003

Shaking table tests and pseudo-static analysis were performed, in this study, on newly-designed aseismatic L-type caisson quay walls, which were constructed by extending the bottom plate of gravity quay walls into the backfill soil. The L-type quay walls are expected to give economical benefits by reducing the cross-sectional area of the wall while maintaining its aseismatic efficiency as much as the classical caisson gravity quay wall. To confirm the effectiveness of the L-type structure, the geometry of L-type quay walls were varied for shaking table tests. And, to verify the influence of backfill soils on the seismic behavior of quay walls, additional shaking table tests were performed on the L-type quay wall after the backfill soils were replaced by gravels and light materials. As a result, it was found that L-type caisson quay walls are good earthquake resistant structures but increasing the length of bottom plate did not proportionally increase the effectiveness of the structure in its aseismatic performance. Replacing the backfill soils by the gravels and light materials, contrary to our expectation, was not an effective measure in improving the seismic performance of L-type caisson quay wall.

• Steel and Composite Structures
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• 제43권2호
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• pp.201-219
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• 2022

This paper firstly proposed high performance composite columns for cold-region infrastructures using ultra-high performance concrete (UHPC) and ultra-high strength steel (UHSS) Q960E. Then, 24 square UHPC-filled UHSS tubes (UHSTCs) at low temperatures of -80, -60, -30, and 30℃ were performed under axial loads. The key influencing parameters on axial compression performance of UHSS were studied, i.e., temperature level and UHSS-tube wall thickness (t). In addition, mechanical properties of Q960E at low temperatures were also studied. Test results revealed low temperatures improved the yield/ultimate strength of Q960E. Axial compression tests on UHSTCs revealed that the dropping environmental temperature increased the compression strength and stiffness, but compromised the ductility of UHSTCs; increasing t significantly increased the strength, stiffness, and ductility of UHSTCs. This study developed numerical and theoretical models to reproduce axial compression performances of UHSTCs at low temperatures. Validations against 24 tests proved that both two methods provided reasonable simulations on axial compression performance of UHSTCs. Finally, simplified theoretical models (STMs) and modified prediction equations in AISC 360, ACI 318, and Eurocode 4 were developed to estimate the axial load capacity of UHSTCs at low temperatures.

• 한국재난정보학회 논문집
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• 제7권3호
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• pp.171-180
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• 2011

최근 발생한 일본 대지진으로, 지진에 대한 피해를 최소화 할 수 있는 내진 설계의 필요성과 기존 구조물의 성능 향상에 대한 관심이 더욱 증가하고 있다. 사회기반시설물인 교량 등의 손상 붕괴는 사회적 경제적으로 미치는 파급효과가 커 이러한 구조물에 대한 내진성능의 평가가 상당히 중요하게 부각되고 있다. 내진성능에 대한 검토방법들은 결정론적 방법에 의한 것이 대다수로 각각의 부재에 대한 안전성 수준의 평가에는 실용적이지만 전체의 안전성 평가에는 실용적이지 못해 지진에 대한 구조물의 안전성 평가에는 손상단계에 따른 취약성 또는 손상도를 평가하는 방법이 필요하다. 본 논문에서는 탄성마찰포트받침(RFPB)을 사용한 Steel Box 교량에 대하여 지진의 특성인 PGA, PGV, SA, SV, SI 에 대한 손상도 곡선을 구하고, 이를 마찰포트받침(FPB)을 갖는 교량의 손상도곡선과 비교함으로써 두 지진 격리 장치의 성능을 비교 평가하였다.

• 국제초고층학회논문집
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• 제9권3호
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• pp.221-233
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• 2020

Based on past experiences of natural disasters and fires in Japan, it is stipulated by law that fire-resistant buildings larger than a certain size should be unique in the world. Recent interest in global environmental issues has led to the active introduction of wooden buildings also in Japan, and it is expected that wooden buildings will become larger and higher in size. This paper introduces the background of the development of fire-resistant laminated timber with a "Self-Charring-Stop layer", the contents of this development including other related developments, and the application of these technologies. In addition, towards the realization of much larger and higher buildings in the future, the current problems and issues to be solved are set and the necessity of the future technological development is described. Finally, a conceptual model of wooden high-rise building is proposed, which will be able to be constructed in 2025 by the further technological development.

• Earthquakes and Structures
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• 제4권4호
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• pp.341-363
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• 2013

Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

• 한국구조물진단유지관리공학회 논문집
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• 제22권4호
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• pp.83-90
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• 2018

전 세계적으로 테러의 위협이 가중되고 일반 상업건축에 대한 방폭설계의 요구가 증가하고 있는 현실을 직시하여, 본 연구에서는 기본적인 방폭설계의 개념을 정립하고 실제 설계사례를 통하여 방폭성능을 평가하는데 목표를 두고 있다. 비록 지진하중과 폭파하중에는 많은 차이점이 있지만, 그 설계법은 구조물의 소성거동을 허용하고 연성을 갖도록 설계한다는 점에서 유사하다. 본 연구에서 제시된 대상 건물에 대한 방폭성능 평가를 통하여, 일반하중에 대하여 잘 설계된 건물은 어느 정도 수준의 방폭성능을 확보하는 것으로 나타났다. 그러나 구조물에 작용하는 폭파하중은 무기의 종류, 등가의 TNT량, 폭발점에서 목표물까지의 최단거리인 촛점거리 등에 따라 달라지기 때문에 일반화하기에는 무리가 있다. 희생구조물을 배치하거나 예상되는 폭발점에서 주요 구조부재까지의 촛점거리를 일정수준 이상으로 유지하는 건축 계획적인 노력은 건물의 방폭성능을 향상시킬 수 있는 쉽고 효과적인 방법이다.