• Structural Engineering and Mechanics
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• 제83권3호
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• pp.401-413
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• 2022

The collapse of civil infrastructure due to natural disasters results in financial losses and many casualties. In particular, the recent increase in earthquake activities has highlighted on the importance of assessing the seismic performance and predicting the seismic risk of a structure. However, the nonlinear behavior of a structure and the uncertainty in ground motion complicate the accurate seismic response prediction of a structure. Artificial intelligence can overcome these limitations to reasonably predict the nonlinear behavior of structures. In this study, a deep learning-based algorithm was developed to estimate the time-history seismic response of bridge structures. The proposed deep neural network was trained using structural and ground motion parameters. The performance of the seismic response prediction algorithm showed the similar phase and magnitude to those of the time-history analysis in a single-degree-of-freedom system that exhibits nonlinear behavior as a main structural element. Then, the proposed algorithm was expanded to predict the seismic response and fragility prediction of a bridge system. The proposed deep neural network reasonably predicted the nonlinear seismic behavior of piers and bearings for approximately 93% and 87% of the test dataset, respectively. The results of the study also demonstrated that the proposed algorithm can be utilized to assess the seismic fragility of bridge components and system.

• Structural Engineering and Mechanics
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• 제60권4호
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• pp.595-614
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• 2016

By taking the Runyang Highway Bridge over the Yangtze River with 1490 m main span as example, structural response of the bridge under the horizontal and vertical seismic excitations is investigated by the response spectrum and time-history analysis of MIDAS/Civil software respectively, the seismic behavior and the influence of structural nonlinearity on the seismic response of the bridge are revealed. Considering the aspect of seismic performance, the suitability of employing the suspension bridge in super long-span bridges is investigated as compared to the cable-stayed bridge and cable-stayed-suspension hybrid bridge with the similar main span. Furthermore, the effects of structural parameters including the span arrangement, the cable sag to span ratio, the side to main span ratio, the girder height, the central buckle and the girder support system etc on the seismic performance of the bridge are investigated by the seismic response spectrum analysis, and the favorable earthquake-resistant structural system of suspension bridges is also discussed.

• Structural Engineering and Mechanics
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• 제55권6호
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• pp.1203-1221
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• 2015

By taking a cable-stayed-suspension hybrid bridge with main span of 1400 m as example, seismic response of the bridge under the horizontal and vertical seismic excitations is investigated numerically by response spectrum analysis and time history analysis, its seismic performance is discussed and compared to the cable-stayed bridge and suspension bridge with the same main span, and considering the aspect of seismic performance, the feasibility of using cable-stayed-suspension hybrid bridge in super long-span bridges is discussed. Under the horizontal seismic action, the effects of structural design parameters including the cable sag to span ratio, the suspension to span ratio, the side span length, the subsidiary piers in side spans, the girder supporting system and the deck form etc on the seismic performance of the bridge are investigated by response spectrum analysis, and the favorable values of these design parameters are proposed.

• 한국지진공학회논문집
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• 제27권6호
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• pp.253-263
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• 2023

Non-structural elements, such as equipment, are typically affixed to a building's floor or ceiling and move in tandem with the structure during an earthquake. Seismic forces acting upon non-structural elements traverse the ground and the building's structure. Considering this seismic load transmission mechanism, it becomes imperative to account for the interactions between soil, structure, and equipment, establishing seismic design procedures accordingly. In this study, a Soil-Structure-Equipment Interaction (SSEI) model is developed. Through seismic response analysis using this model, how the presence or absence of SSEI impacts equipment behavior is examined. Neglecting the SSEI aspect when assessing equipment responses results in an overly conservative evaluation of its seismic response. This emphasizes the necessity of proposing an analytical model and design methodology that adequately incorporate the interaction effect. Doing so enables the calculation of rational seismic forces and facilitates the seismic design of non-structural elements.

• 한국지진공학회논문집
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• 제21권6호
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• pp.265-275
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• 2017

In order to improve the seismic performance of structures, friction pendulum system (FPS) is the most commonly used seismic isolation device in addition to lead rubber bearing (LRB) in high seismicity area. In a nuclear power plant (NPP) with a large self weight, it is necessary to install a large number of seismic isolation devices, and the position of the center of rigidity varies depending on the arrangement of the seismic isolation devices. Due to the increase in the eccentricity, which is the difference between the center of gravity of the nuclear structure and the center of stiffness of the seismic isolators, an excessive seismic response may occur which could not be considered at the design stage. Three different types of eccentricity models (CASE 1, CASE 2, and CASE 3) were used for seismic response evaluation of seismically isolated NPP due to the increase of eccentricity (0%, 5%, 10%, 15%). The analytical model of the seismic isolation system was compared using the equivalent linear model and the bilinear model. From the results of the seismic response of the seismically isolated NPP with increasing eccentricity, it can be observed that the effect of eccentricity on the seismic response for the equivalent linear model is larger than that for the bilinear model.

• 한국공간구조학회논문집
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• 제8권6호
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• pp.49-57
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• 2008

지진에 의한 구조물의 응답을 저감시키기 위하여 다양한 면진장치가 사용되고 있으며 면진장치가 설치된 구조물은 고유주기가 길어져서 지진파의 탁월 주기를 벗어나게 된다. 대공간 구조물의 상부(지붕)구조인 트러스 아치는 하부구조인 기둥에 의하여 지지되는 경우가 있을 수 있다. 본 연구에서는 하부 기둥에 따른 면진 트러스 아치구조물의 거동을 분석하고자 한다. 면진장치를 대공간 구조물에 적용할 경우에 수평지진하중에 의하여 수평방향 지진응답이 저감되는 것은 물론 면진장치의 수직강성으로 인하여 수직응답도 현저하게 저감되는 것을 알 수 있었다. 하부의 기둥 강성이 큰 경우에 트러스 아치의 거동은 기둥 없이 트러스 아치가 지반에 직접 지지되는 트러스 아치의 거동과 유사하게 나타나고 있다. 또한 하부구조의 강성이 비교적 작은 대공간구조물에 면진장치를 적용할 경우에는 지진응답에 대한 우수한 제어 성능을 얻을 수 있을 것이다.

• 한국공간구조학회논문집
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• 제13권1호
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• pp.113-119
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• 2013

Spatial structures have the different dynamic characteristics from general rahmen structures. Therefore, it is necessary to accurately analyze dynamic characteristics and seismic response of spatial structure for seismic design of spatial structure. An arch structure is used as an example structure because it has primary characteristics of spatial structures. Multiple support excitation may be subjected to supports of a spatial structure because ground condition of spatial structures is different. In this study, the response analysis of the arch structure under multiple support excitation and simple support excitation is studied. By means of the pseudo excitation method, the seismic response is analyzed for long span spatial structure. It shows that the structural response is divided into two parts, ground displacement and structural dynamic response due to ground motion excitation. It is known that the seismic response of spatial structure under multiple support excitation and simple support excitation are the different in some case. Therefore, it has to be necessary to analyze the seismic response of spatial structure under multiple support excitation because the spatial structure supports may be different.

• 한국지진공학회논문집
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• 제22권3호
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• pp.113-119
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• 2018

The probabilistic seismic safety assessment is one of the methodology to evaluate the seismic safety of the nuclear power plants. The site characteristics of the nuclear power plant should be reflected when evaluating the seismic safety of the nuclear power plant. The Korea seismic characteristics are strong in high frequency region and may be different from NRC Regulatory Guide 1.60, which is the design spectrum of nuclear power plants. In this study, seismic response of a nuclear power plant structure by Pohang earthquake (2017.11.15. (KST)) is investigated. The Pohang earthquake measured at the Cheongsong seismic observation station (CHS) is scaled to the peak ground acceleration (PGA) of 0.2 g and the seismic acceleration time history curve corresponding to the design spectrum is created. A nuclear power plant of the containment building and the auxiliary buildings are modeled using OPENSEES to analyze the seismic response of the Pohang earthquake. The seismic behavior of the nuclear power plant due to the Pohang earthquake is investigated. And the seismic performances of the equipment of a nuclear power plant are evaluated by the HCLPF. As a result, the seismic safety evaluation of nuclear power plants should be evaluated based on site-specific characteristics of nuclear power plants.

• 한국공간구조학회논문집
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• 제18권3호
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• pp.133-140
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• 2018

Vertical earthquake motions can occur along with horizontal earthquakes, so that Structure should be designed to resist Seismic loads in all directions. Especially, due to the dynamic characteristics such as the vibration mode, when the vertical seismic load, the dynamic response of the Spatial structure is large. In this study, the seismic response of the lattice dome to horizontal and vertical seismic loads is analyzed, and a reasonable seismic load combination is analyzed by combining horizontal and vertical seismic response results. In the combination of the horizontal seismic load, the largest result is obtained when the direction of the main axis of the structure coincides with the direction of seismic load. In addition, the combination of vertical seismic load and horizontal seismic load was the largest compared with the combination of horizontal seismic load. Therefore, it is considered that the most reasonable and stable design will be achieved if the seismic load in vertical direction is considered.

• Earthquakes and Structures
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• 제2권4호
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• pp.337-356
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• 2011

In this paper, cable-stayed bridges with single pylon and two equal side spans, with variations in geometry and span ranging from 120 m to 240 m have been studied. 3D models of the bridges considered in this study have been analysed using ANSYS. As the first step towards a detailed seismic analysis, free vibration response of different geometries is studied for their mode shapes and frequencies. Typical pattern of free vibration responses in different frequencies with change in geometry is observed. Further, three different seismic loading histories are chosen with various characteristics to find the structural response of different geometries under seismic loading. Effect of variation in pylon shape, cable arrangement with variation in span is found to have typical characteristics with different structural response under seismic loading. From the study, it is observed that the structural response is very much dependent on the geometry of the cable-stayed bridge and the characteristics of the seismic loading as well. Further, structural responses obtained from the study would help the design engineers to take decisions on geometric shapes of the bridges to be constructed in seismic prone zones.