Procedure for Ranking Ground Motion Records Based on the Destructive Capacity Parameter

Jinjun Hu,Qinghui Lai,Shuang Li,Lili Xie 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.1

The relative input energy of a ground motion is used to quantitatively estimate the destructive capacity of ground motion to a structure, which reflects the deformation capacity and energy dissipation capacity of a structure. The destructive capacity of a ground motion on a structure is known to be relevant to the structural period. Because ranking the destructive capacity of ground motion at all periods is not practical, rationally dividing period ranges should be performed before ranking ground motions according to their destructive capacity and a new method to divide period ranges based on the relative input energy is proposed. According to the correlation coefficient of the relative input energy at adjacent structural periods, the structural periods from 0.2 s to 10 s are divided into several representational period ranges, which include a recommended period within each period range to represent the whole range. Only the ground motion ranking sequence at the recommended period is used in this period range. The rationality of the ranking sequence of ground motions based on destructive capacity is verified by a series of structural seismic response analyses. The results of this paper are compared with those of existing methods, and the results show that the relative input energy index is able to better quantitatively describe the destructive capacity of ground motion.

2016년 경주지진 원인단층의 시나리오 지진에 의한 국내 광역도시 지진관측소에서의 추계학적 강진동 모사

최호선,Choi, Hoseon 한국지진공학회 2021 한국지진공학회논문집 Vol.25 No.6

The stochastic method is applied to simulate strong ground motions at seismic stations of seven metropolises in South Korea, creating an earthquake scenario based on the causative fault of the 2016 Gyeongju earthquake. Input parameters are established according to what has been revealed so far for the causative fault of the Gyeongju earthquake, while the ratio of differences in response spectra between observed and simulated strong ground motions is assumed to be an adjustment factor. The calculations confirm the applicability and reproducibility of strong ground motion simulations based on the relatively small bias in response spectra between observed and simulated strong ground motions. Based on this result, strong ground motions by a scenario earthquake on the causative fault of the Gyeongju earthquake with moment magnitude 6.5 are simulated, assuming that the ratios of its fault length to width are 2:1, 3:1, and 4:1. The results are similar to those of the empirical Green's function method. Although actual site response factors of seismic stations should be supplemented later, the simulated strong ground motions can be used as input data for developing ground motion prediction equations and input data for calculating the design response spectra of major facilities in South Korea.

Seismic Response of Long Span Cable-stayed Bridge to Near-fault Vertical Ground Motions

Bipin Shrestha 대한토목학회 2015 KSCE Journal of Civil Engineering Vol.19 No.1

In design and analysis of seismic resistant structures and particularly the bridge structures vertical ground motion tends, in general,to be ignored or underestimated. However, during recent earthquakes high amplitude of motions were recorded in vertical directionnear to the fault, invalidating such design assumptions of neglecting the vertical motion. This paper presents an analyticalinvestigation on the effect of the near fault vertical ground motions on seismic response of a long span cable-stayed bridge. Responses of the bridge subjected to ground motions with and without vertical ground motion is carried using near fault groundmotions on three dimensional bridge model. A suite of five near field ground motion with varying V/H (Vertical to Horizontal) ratioof peak ground acceleration is used. Influence of vertical motion on global and local structural response is presented. The study alsotakes into consideration the arrival time of peak vertical motion which has received little attention previously. Effects of coincidenceof peak vertical motion with the peak horizontal motion in time domain are also analyzed. The study reveals that influence of verticalmotion on the seismic response of the Karnali Bridge is slight and coinciding peak vertical motion with peak horizontal motion alsohave slighter effects compared to the motion without such coincidence.

목표스펙트럼에 근사한 평균응답스펙트럼을 갖는 지반운동집단의 효율적인 선정방법

한상환,석승욱 한국지진공학회 2011 한국지진공학회논문집 Vol.15 No.5

본 연구에서는 지반운동 라이브러리에서 목표스펙트럼에 근사한 평균응답스펙트럼을 갖는 한 개 혹은 다수의 지반운동을 선정하는 효율적인 방법을 제안하고자 한다. 지반운동 선정 시 목표스펙트럼의 형상과 크기를 맞추어야 하는데 이 두 가지를 독립적으로 고려할 수 있다는 기존 연구결과에 따라 본 연구에서도 형상이 가장 유사한 지반운동을 찾고 크기를 맞추기 위하여 배율조정계수를 사용한다. 형상을 맞추기 위해 각 주기에서 목표스펙트럼과 지반운동 평균응답스펙트럼의 차이 값의 표준편차가 최소가 되도록 하여 선정하는 방법을 제안하였다. 형상이 결정된 후 그 크기를 맞추기 위해 본 연구에서 제안한 배율조정계수를 찾는 방법은 기존 연구와 달리 한번에 찾을 수 있도록 제안하였다. 40개의 지반운동 라이브러리로부터 제안한 방법을 이용하여 목표스펙트럼에 근사한 평균스펙트럼을 갖는 7개의 지반운동기록을 선정한 결과, 그 정확성과 계산소요시간에 있어 모두 만족할만한 결과를 보였다. This paper proposes an efficient method for selecting ground motions with the mean response spectrum matching a target spectrum. Since former studies reported that the shape and amplitude of the response spectra can be treated independently for selecting ground motions, this study first selects ground motions such that the shape of their mean response spectrum matches that of the target spectrum, then scales the ground motions. To select the ground motions best matching the shape of the target response spectrum, the standard deviation of the difference between the target response spectrum and the mean response spectrum of the selected ground motions needs to be minimized. Unlike the existing procedure, the scaling factor can be computed without iteration. Based on the selection results of 7 ground motions from a library of 40 ground motions, the proposed method is verified as an accurate and efficient method.

설계용 스펙트럼에 적합한 인공지진동의 에너지 응답특성의 평가

전대한(Jun Dae-Han),양창진(Yang Chang-Jin) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.5

It has long been recognized that energy input, absorption, and dissipation in seismic resistant design of structures are the most fundamental quantities controlling seismic performance. While the input energy(EI) is a reliable parameter for selecting the most demanding earthquake ground motion, it alone is not sufficient for proper seismic design of the structure. The importance of reliable estimation of the input energy of possible earthquake ground motions at the site of structure in order to select the proper design earthquake motion is emphasized. This paper discusses the characteristic of input energy concepts between the real recorded ground motion and the artificial ground motion in seismic resistant design of building structures. For long-period contents dominant earthquake ground motion, the input energy spectra are sensitive to the variation of the natural period of structures. It is concluded that the input energy quantities by the artificial ground motions used in this paper presented better stability than those by real recorded ground motions. Also, the artificial ground motions compatible with design spectrum are applicable as input ground motions for a seismic response analysis of building structures.

연약지반에 건설된 단일형 현장타설말뚝 교량의 근단층지반운동에 대한 내진성능

선창호,안성민,김정한,김익현 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 논문집 Vol.23 No.7

For the structures near the seismogenic fault, the evaluation of seismic performance against near-fault ground motions is important as well as for design ground motions. In this study, characteristics of seismic behaviors and seismic performance of the pile-bent bridge constructed on the thick soft soil site with various weak soil layers were analyzed. The input ground motions were synthesized by the directivity pulse parameters for intra-plate regions. The ground motion acceleration histories of each layer were obtained by one-dimensional site response analysis. Each soil layer was modeled by equivalent linear springs, and multi-support excitations with different input ground motions at each soil spring were applied for nonlinear seismic analyses. The analysis result by the near-fault ground motions and ground motions matched to design spectra were compared. In case of the near fault ground motion input, the bridge behaved within the elastic range but the location of the maximum moment occurred was different from the result of design ground motion input. 근단층 지역에 위치한 교량은 근단층지반운동에 대한 내진안전성을 확보하는 것이 중요하다. 본 연구에서는 연약지반이 두껍고 다양한 지층으로 구성된 지역에 건설되는 단일형 현장타설말뚝 교량의 지진거동특성과 내진안전성을 분석하였다. 근단층지반운동을 생성하고 지반해석을 수행하여 각 지층에서의 지반가속도이력을 산정하였다. 이 가속도이력을 이용하여 각 지층의 지반을 등가스프링으로 모델화하고, 각 지층에서의 가속도시간이력을 입력지반운동으로 하는 다지점 가진 지진해석을 수행하였다. 근단층지반운동의 특성으로 인하여 교량은 탄성영역 내에서 거동하였지만 최대모멘트의 발생 위치 등이 설계지반운동을 고려할 때와는 상이한 특성을 보였다.

경험적 그린함수를 이용한 강지진동 합성에 관한 연구

김준경,이상훈 한국지진공학회 2006 한국지진공학회논문집 Vol.10 No.1

지진공학 분야에서는 내진설계를 위한 필요성으로 인해 근역의 강지진동이 관심의 대상이 되어왔으며, 최근 우리나라의 모든 구조물에 내진설계가 의무화되면서 그 필요성은 더욱 부각되고 있는 상황이다. 본 연구에서는 특정부지에서의 강지진동 합성을 위하여 경험적 그린함수 방법을 이용한 합성방법을 적용하였다. 이 합성방법은 Haskell 타입의 운동학적 지진원 모델과 동일한 지역에서 발생한 지진의 유사성 이론을 기본으로 하고 있다. 합성에 이용되는 변수들은 단층길이, 폭 및 변위지속 시간과 같은 단층변수와 모멘트간의 일관된 관계로부터 결정된다. 본 연구에서 적용된 합성방법을 1997년 3월27일 일본의 동일지역에서 차례로 발생한 2개의 중규모(ML 4.7) 및 대규모 지진(ML 6.5)에 대하여 적용하여 강지진동을 합성하고 결과를 분석하였다. 본 연구방법을 적용한 결과 중규모(ML 4.7) 오부터 관측된 강지진동을 이용하여 가속도, 속도 및 변위 성분에서 합성된 강지진동은 파형뿐만 아니라 전체 진동수 대역에서 대체적으로 실제 강지진동을 양호하게 예측하는 경향을 보였다. 또한, 전체적으로 합성운동의 첨두값 역시 실제 계측된 첨두값과 비교할 때 만족스러운 정도로 일치하는 결과를 보여주었다. 특히 가속도이력의 첨두값은 단지 약 8.8%만의 차이를 보여주었다. The research on strong ground motions became important recently due to more severe requirement of seismic design for the domestic buildings and structures. The empirical Green's function method, which uses similarities between small and large earthquakes, was applied to make synthetic ground motions. That method was applied to the 2 earthquakes which occurred sequently in time within narrow area in Japan. The strong ground motions for the virtual earthquake (magnitude 6.5) were synthesized using those observed from the magnitude 4.7 earthquake. Then, the synthesized ground motions (acceleration, velocity, and displacement) were compared to those observed from real earthquake (magnitude 6.5). The results showed that the general shapes of waveforms in time domain and the Fourier spectrum In frequency domain from synthesized ground motions (acceleration, velocity, and displacement) are similar to the observed strong ground motions within acceptable degree. The peak values of 3 kinds of synthesized strong ground motions in time domain are comparable between the synthesized and the real strong ground motions, especially only about 9% difference in acceleration peak value.

설계용 스펙트럼에 적합한 인공지진동의 에너지 응답특성의 평가

전대한,양창진,Jun, Dae-Han,Yang, Chang-Jin 대한건축학회 2012 대한건축학회논문집 Vol.28 No.5

It has long been recognized that energy input, absorption, and dissipation in seismic resistant design of structures are the most fundamental quantities controlling seismic performance. While the input energy($E_I$) is a reliable parameter for selecting the most demanding earthquake ground motion, it alone is not sufficient for proper seismic design of the structure. The importance of reliable estimation of the input energy of possible earthquake ground motions at the site of structure in order to select the proper design earthquake motion is emphasized. This paper discusses the characteristic of input energy concepts between the real recorded ground motion and the artificial ground motion in seismic resistant design of building structures. For long-period contents dominant earthquake ground motion, the input energy spectra are sensitive to the variation of the natural period of structures. It is concluded that the input energy quantities by the artificial ground motions used in this paper presented better stability than those by real recorded ground motions. Also, the artificial ground motions compatible with design spectrum are applicable as input ground motions for a seismic response analysis of building structures.

Distribution of Shear Coefficient of Multi-story Buildings Subjected to Near-fault Ground Motions

Wuchuan Pu,Ruijun Liang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.9

In static seismic design, the strength demands of structural members are decided based on the expected shear force in a seismic event. A reasonable shear force distribution pattern leads to a reasonable configuration of structural parameters and thus makes the structure behave as expected in the design stage. In current seismic codes, the shear force distribution patterns are established based on the elastic response of structures subjected to ordinary far-fault ground motions. Because structural responses induced by pulselike near-fault ground motions are substantially different from the responses induced by far-fault ground motions, shear force patterns specified in current codes are not suitable for the structural design against near-fault ground motions, and a shear force distribution pattern considering the near-fault effect should be established. This study aims to investigate the characteristics of shear coefficients resulting from near-fault ground motions and to provide a new shear force distribution pattern specifically for seismic design against near-fault ground motions. To achieve this goal, dynamic time history analyses are performed on elastic shear models based on 50 near-fault ground motions, and the shear force distributions are analyzed statistically. Findings from the study reveal that the higher modes contribute substantially to the shear coefficient, and the contribution is affected by the pulse period of the ground motion and the structural damping. The shear coefficients for floor levels 2/3 of the way up the height of the structure are significantly larger than code-specified values, if the structure has a limited damping ratio. Based on the numerical results, an empirical formula of the shear coefficient pattern is proposed. In this formula, the effects of damping ratio and period ratio are taken into account, and it can be used to derive shear coefficients more suitable for structures subjected to pulse-like near-fault ground motions.

장주기 지진동을 고려한 건축물 및 비구조요소의 가속도 응답 증폭비

오상훈,김주찬 한국지진공학회 2023 한국지진공학회논문집 Vol.27 No.1

Structures of high-rise buildings are less prone to earthquake damage. This is because the response acceleration of high-rise buildings appears to be small by generally occurring short-period ground motions. However, due to the increased construction volume of high-rise buildings and concerns about large earthquakes, long-period ground motions have begun to be recognized as a risk factor for high-rise buildings. Ground motion observed on each floor of the building is affected by the eigenmode of the building because the ground motion input to the building is amplified in the frequency range corresponding to the building's natural frequency. In addition, long-period components of ground motion are more easily transmitted to the floor or attached components of the building than short-period components. As such, high-rise buildings and non-structural components pose concerns about long-period ground motion. However, the criteria (ASCE 7-22) underestimate the acceleration response of buildings and non-structural components caused by long-period ground motion. Therefore, the characteristics of buildings’ acceleration response amplification ratio and non-structural components were reviewed in this study through shake table tests considering long-period ground motions.