• 한국지진공학회논문집
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• 제25권6호
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• pp.241-249
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• 2021

Communication facilities play an essential role in disaster situations. Therefore, communication facilities need to have structural and functional safety during and after earthquakes. Recently, technology for partial seismic isolation has been increasing to protect data facilities and communication equipment installed in buildings from earthquakes. However, excessive displacement may occur in the seismic isolator during an earthquake due to the resonance between the building and the seismic isolator having long-period characteristics, which may cause overturning and separation of the installed equipment. In this study, analytical and experimental studies were conducted to evaluate the safety of seismic isolators installed in high-rise buildings. It was confirmed that damages might occur in buildings' seismic isolator, with resonance characteristics of less than 1 Hz.

• 한국건축시공학회지
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• 제17권1호
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• pp.9-14
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• 2017

본 연구에서 비정질 붕소강 섬유를 혼입한 콘크리트의 역학적 성능 및 중성자 차폐성능을 평가하였다. 비정질 붕소강 섬유를 콘크리트 체적 대비 0.25%에서 1.0%까지 혼입하여 굳지 않은 콘크리트의 공기량과 슬럼프값, 경화된 콘크리트의 압축강도, 휨강도, 휨인성 및 중성자 차폐성능을 평가하였다. 실험결과, 비정질 붕소강 섬유의 혼입량이 증가할수록 콘크리트의 휨인성 및 중성자 차폐성능이 향상되는 것으로 나타났다. 이를 통해 비정질 붕소강 섬유의 혼입이 중성자 차폐성능 뿐만 아니라 역학적 성능을 효과적으로 개선시켜 줄 것이라고 기대된다.

• 한국건축시공학회지
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• 제10권5호
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• pp.21-29
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• 2010

희생양극방식은 지하구조물이나 해양환경하에서 구조물의 방식공법으로 소개되어지고 있다. 1970년대 이후, 희생양극방식이 철근콘크리트 구조물에 적용되어지고 있다. 희생양극방식은 전세계적으로 1990년대 이후 그 유효성을 검증되었다. 그러나, 희생양극방식은 시공적이나 경제적인 약간의 문제점을 가지고 있다. 그 문제점을 해결하기 위하여 고 내구성 금속을 용사시키는 희생양극방식이 개발되었다. 양극재(아연, 알루미늄)를 금속용사로 도포하여 실험체를 제작한 후, 실험체의 부식전류를 측정하여 양극재의 방식성능을 확인하였다. 실험결과 철근 콘크리트 구조물을 대상으로 금속용사를 이용한 희생양극방식이 우수한 방식성능을 가지는 것을 알 수 있었다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권3호
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• pp.127-135
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• 2019

본 논문은 기존 RC 보강방법인 철골프레임 적용방법의 단점을 보완하고자, 접합철물을 최소화하고 팽창형 모르타르를 사용하여 H형강 프레임을 기존 RC 골조에 보강하고자 하였다. 철골프레임 적용 유.무를 변수로 RC 골조에 대한 반복가력실험을 실시하여 내진성능을 평가하였다. 철골프레임을 적용한 RC 골조의 최대내력이 기존 RC 골조에 비해 약 1.4배 향상되었으며, 등가점성감쇠비 평가결과 또한 평균 2.4% 향상되어 에너지 소산능력이 개선되었다. 유한요소해석결과 해당 실험결과가 신뢰성을 가질 수 있는 것으로 판단된다.

• Earthquakes and Structures
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• 제19권1호
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• pp.59-77
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• 2020

The code static eccentricity model for elastic torsional design of structures has two critical shortcomings: (1) the negation of the inertial torsional moment at the center of mass (CM), particularly for torsionally-unbalanced (TU) building structures, and (2) the confusion caused by the discrepancy in the definition of the design eccentricity in codes and the resistance eccentricity commonly used by engineers such as in FEMA454. To overcome these shortcomings, using the resistance eccentricity model that can accommodate the inertial torsional moment at the CM, interactive relations between shear and torsion are proposed as follows: (1) elastic responses of structures at instants of peak edge-frame drifts are given as functions of resistance eccentricity, and (2) elastic hysteretic relationships between shear and torsion in forces and deformations are bounded by ellipsoids constructed using two adjacent dominant modes. Comparison of demands estimated using these two interactive relations with those from shake-table tests of two TU building structures (a 1:5-scale five-story reinforced concrete (RC) building model and a 1:12-scale 17-story RC building model) under the service level earthquake (SLE) show that these relations match experimental results of models reasonably well. Concepts proposed in this study enable engineers to not only visualize the overall picture of torsional behavior including the relationship between shear and torsion with the range of forces and deformations, but also pinpoint easily the information about critical responses of structures such as the maximum edge-frame drifts and the corresponding shear force and torsion moment with the eccentricity.

• Earthquakes and Structures
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• 제4권2호
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• pp.157-179
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• 2013

Vulnerability studies on the existing building stock require that a large number of buildings is analyzed to obtain statistically significant evaluations of the seismic performance. Therefore, analytical evaluation methods need to be based on simplified methodologies of analysis which can afford the treatment of a large building population with a reasonable computational effort. Simplified Pushover-Based Earthquake Loss Assessment approach (SP-BELA), where a simplified methodology to identify the structural capacity of the building through the definition of a pushover curve is adopted, was developed on these bases. Main objective of the research work presented in this paper is to validate the simplified methodology implemented in SP-BELA against the results of more sophisticated nonlinear dynamic analyses (NLDAs). The comparison is performed for RC buildings designed only to vertical loads, representative of the "as built" in Italy and in Mediterranean countries with a building stock very similar to the Italian one. In NLDAs the non linear and degrading behaviour, typical of the structures under consideration when subjected to high seismic loads, is evaluated using models able to capture, with adequate accuracy, the non linear behaviour of RC structural elements taking into account stiffness degradation, strength deterioration, and pinching effect. Results show when simplified analyses are in good agreement with NLDAs. As a consequence, unsatisfactory results from simplified analysis are pointed out to address their current applicability limits.

• Earthquakes and Structures
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• 제5권6호
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• pp.703-731
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• 2013

In order to verify the applicability of buckling restrained braces (BRB's) and fiber reinforced polymer (FRP) sheets to the seismic strengthening of a low-rise RC building having the irregularities of a soft/weak story and torsion at the ground story, a series of earthquake simulation tests were conducted on a 1:5 scale RC building model before, and after, the strengthening, and these test results are compared and analyzed, to check the effectiveness of the strengthening. Based on the investigations, the following conclusions are made: (1) The BRB's revealed significant slips at the joint with the existing RC beam, up-lifts of columns from RC foundations and displacements due to the flexibility of foundations, and final failure due to the buckling and fracture of base joint angles. The lateral stiffness appeared to be, thereby, as low as one seventh of the intended value, which led to a large yield displacement and, therefore, the BRB's could not dissipate seismic input energy as desired within the range of anticipated displacements. (2) Although the strengthened model did not behave as desired, great enhancement in earthquake resistance was achieved through an approximate 50% increase in the lateral resistance of the wall, due to the axial constraint by the peripheral BRB frames. Finally, (3) whereas in the original model, base torsion was resisted by both the inner core walls and the peripheral frames, the strengthened model resisted most of the base torsion with the peripheral frames, after yielding of the inner core walls, and represented dual values of torsion stiffness, depending on the yielding of core walls.

• 한국구조물진단유지관리공학회 논문집
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• 제24권4호
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• pp.10-17
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• 2020

최근 국내에 발생한 지진으로 인해 많은 학교 건물들에 크고 작은 피해가 발생하였다. 학교 건축물은 재난 발생시 대피소로 사용되는 중요 건물로서 비내진 건축물일 경우 여러 방법으로 내진 보강이 진행 중이다. 내진보강 공법 중 내부 철골가새골조형 공법은 비교적 시공이 용이하고 성능이 우수하여 많이 사용되고 있다. 본 연구에서는 기존 철근콘크리트 학교 건물에 철골 가새 골조를 적용하여 수평반복가력해석을 수행하여 최대전단력 및 변위를 비교검토 하였다. 그 결과로 해석 모델의 적정성을 확인하였고, 기존 학교 건축물의 1경간에 대한 가새- 높이비에 따른 효과를 비교 검토하였다. 가새- 높이비 0.3의 모델에서 최대 전단내력과 변위관계에서의 적정성을 확인할 수 있었다. 또한, 실제 비 내진 철근콘크리트 학교 건축물에 철골가새를 적용시켜 가새- 높이비에 따른 비선형정적해석을 수행하여 내진 성능을 검토하였다. 그 결과, 가새- 높이비 0.3에서 부재의 붕괴가 없는 적절한 내진효과를 보이고 있다. 가새 높이의 증가는 최대전단력과 인명안전 수준의 성능점에서 최대 하중을 증가시키는 효과를 나타내고 있으나, 횡강성의 증가로 인한 가새 골조 주변 부재의 붕괴가 발생하므로, 적정한 가새 높이에 따른 내진 보강이 필요하다는 것을 알 수 있었다. 따라서, 기존 학교건축물의 가새 골조의 내진보강 설계에 있어서 가새 높이에 따른 보강해석을 고려한 후 가새 높이를 선정하고 적절한 보강 개수와 보강위치를 정하는 것이 필요한 것으로 사료된다.

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.547-571
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• 2023

To deeply probe the actual earthquake level and fragility of typical reinforced concrete (RC) structures under multiple intensity grades, considering diachronic measurement building stock samples and actual observations of representative catastrophic earth shocks in China from 1990 to 2010, RC structures were divided into traditional RC structures (TRCs) and bottom reinforced concrete frame seismic wall masonry (BFM) structures, and the empirical damage characteristics and mechanisms were analysed. A great deal of statistics and induction were developed on the historical experience investigation data of 59 typical catastrophic earthquakes in 9 provinces of China. The database and fragility matrix prediction model were established with TRCs of 4,122.5284×104 m² and 5,844 buildings and BFMs of 5,872 buildings as empirical seismic damage samples. By employing the methods of structural damage probability and statistics, nonlinear prediction of seismic vulnerability, and numerical and applied functional analysis, the comparison matrix of actual fragility probability prediction of TRC and BFM in multiple intensity regions under the latest version of China's macrointensity standard was established. A novel nonlinear regression prediction model of seismic vulnerability was proposed, and prediction models considering the seismic damage ratio and transcendental probability parameters were constructed. The time-varying vulnerability comparative model of the sample database was developed according to the different periods of multiple earthquakes. The new calculation method of the average fragility prediction index (AFPI) matrix parameter model has been proposed to predict the seismic fragility of an areal RC structure.

• Structural Engineering and Mechanics
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• 제35권1호
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• pp.19-35
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• 2010

This paper proposes a hybrid heuristic and criteria-based method of optimum design which combines the advantages of both the iterated simulated annealing (SA) algorithm and the rigorously derived optimality criteria (OC) for structural optimum design of reinforced concrete (RC) buildings under multi-load cases based on the current Chinese design codes. The entire optimum design procedure is divided into two parts: strength optimum design and stiffness optimum design. A modified SA with the strategy of adaptive feasible region is proposed to perform the discrete optimization of RC frame structures under the strength constraints. The optimum stiffness design is conducted using OC method with the optimum results of strength optimum design as the lower bounds of member size. The proposed method is integrated into the commercial software packages for building structural design, SATWE, and for finite element analysis, ANSYS, for practical applications. Finally, two practical frame-shear-wall structures (15-story and 30-story) are optimized to illustrate the effectiveness and practicality of the proposed optimum design method.