기존 비선형약산법들의 신뢰성 개선을 위한 비선형직접스펙트럼법

김재웅,강병두,전대한 한국지진공학회 2006 한국지진공학회논문집 Vol.10 No.4

본 연구에서는 강성골격곡선으로부터 산정한 구조물의 초기 탄성진동주기 T_1와 응답스트럼으로부터 산정한 비선형 유사가속도 A_{1y}/g 및 연성비 {\mu}를 사용하여, 반복적인 계산과정 없이 복합구조물의 내진성능을 평가하는 비선형직접스펙트럼법(NDSM)을 고려한다. 다양한 지진과 복합구조물에 대한 NDSM의 신뢰성과 실용성을 비선형시각이력해석(NRHA) 결과와 비교 검토하였다. 본 연구의 결론은 다음과 같다. (1) NDSM은 강성골격곡선으로부터 기본진동주기와 비선형 항복강도를 구하면, 비선형 응답스펙트럼으로부터 직접적으로 구조물의 비선형 최대응답을 산정할 수 있는 실용적인 방법으로 사료된다. (2) NDSM의 응답을 정산해와 비교한 결과, 대부분의 모델이 단순평균의 관점에서 전체 해석모델 중 3/4이 약 20% 이하의 오차를 나타내었고, 일반적으로 비선형시각이력해석의 응답보다 크게 산정되는 것으로 나타났다. This paper considers the nonlinear direct spectrum method to estimate seismic performance of mixed building structures without iterative computations, given dynamic property T_1 from stiffness skeleton curve and nonlinear pseudo acceleration A_{1y}/g and/or ductility ratio p from response spectrum. Nonlinear response history analysis has been performed and analysed with various earthquakes for evaluation of correctness and confidence of nonlinear direct spectrum method. The conclusions of this study are as follows; (1) Nonlinear direct spectrum method is considered as a practical method which is applicable to compute the structural initial elastic period and the yielding strength from stiffness skeleton owe and calculate the nonlinear maximum response of structure directly from nonlinear response spectrum. (2) The comparison of the analysis results from NDSM and NRHA showed that the average errors were less than 20% in about 3/4 of the analysis cases, and that the results obtained from NDSM turned out to be generally larger than those from NRHA.

복합구조물의 하부골조층수 변화에 따른 비선형 약산법의 응답특성

김재웅,강병두,전대한,남영우 대한건축학회지회연합회 2005 대한건축학회지회연합회 학술발표대회논문집 Vol.1 No.1

One of the most accurate earthquake analysis method for the performance evaluation of structure is nonlinear time history analysis, but it is time-consuming and necessitate more efforts. Approximate methods are presented for estimating the capacity of structures while subjecting earthquake ground motions. This is made by exploiting the connection between the nonlinear static response of structure and the dynamic response of SDF system whose backbone matches the structure’s pushover curve. The capacity spectrum method is one of general approximate methods which is based on equivalent linearization where the inelastic deformation is approximated by the maximum deformation of an equivalent linear elastic system having equivalent viscous damping. It requires iterative computations, because the equivalent damping ratio is computed as a function of the maximum deformation. The nonlinear capacity spectrum method estimate the maximum inelastic deformation of SDF system by nonlinear response spectra. The nonlinear direct spectrum method is proposed and studied to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. In this study, it is to compare the accuracy and the reliability of approximate nonlinear methods with respect to upper wall-lower frame system and various earthquakes.

고차모드의 영향을 고려한 비선형 직접스펙트럼법

박진화,강병두,노필성,김재웅 동아대학교 건설기술연구소 2002 硏究報告 Vol.26 No.1

Recently, a variety of methods are proposed to solve the problems shown in a existing performance-based design of structure. Among those methods, capacity spectrum method(ATC-40, FEMA-273) is one of general methods. The basis of the capacity spectrum method is the idea that the peak response of an inelastic system can be estimated as the peak response of a linear elastic system(equivalent single degree of freedom) with reduced stiffness and increased damping. However, the capacity spectrum method with equivalent SDOF systems characterizing the nonlinear response of multistory structures frequently makes iterative calculations and inaccurate results; and may potentially mislead if higher modes play a significant role in the response. Accordingly, in this study, nonlinear direct spectrum method is proposed and examined as one of methods considering the influence of higher modes to improve accuracy of analysis.

복합구조물에 대한 비선형 직접스펙트럼법의 신뢰성

강병두,김재웅 한국지진공학회 2003 한국지진공학회논문집 Vol.7 No.2

대부분의 구조물들은 강한 지진을 받을 경우, 비선형 거동의 변형이 예상된다. 구조물의 내진평가는 구조물에 가해진 지진력에 대한 변위요구와 같은 구조물의 성능평가를 필요로 한다. 여러 가지 비선형해석법 가운데 구조물의 내진역량을 계산하기 위한 가장 정확한 방법은 비선형 시각이력해석(NRHA)이긴 하나 많은 시간과 노력이 요구되고 있다. 따라서 구조물의 비선형 거동을 보다 간편하게 예측하기 위한 정확하고 실용적인 비선형 약산해석법에 관한 연구들이 활발히 진행되고 있다. 일부 약산적 방법 중 능력스펙트럼법(CSM)은 개념적으로는 간단하나 반복적인 계산과정과 함께 때로는 해가 없거나 중복적인 해를 갖는 약점을 갖고 있다. 본 연구에서는 강성골격곡선으로부터 산정한 구조물의 초기 탄성진동주기 T와 응답스펙트럼으로부터 산정한 비선형 유사가속도 h_{y} /g 및 연성비 \mu를 사용하여, 반복적인 계산과정 없이 복합구조물의 내진성능을 평가하는 비선형 직접스펙트럼법(NDSM)을 고려한다. 다양한 지진과 복합구조물에 대한 NDSM의 신뢰성과 실용성을 비선형 시각이력해석(NRHA) 결과와 비교함으로써 검토하였다. Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. Seismic evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. The nonlinear response history analysis(NRHA) among various nonlinear analysis methods is the most accurate to compute seismic performance of structures, but it is time-consuming and necessitate more efforts. The nonlinear approximate methods, which is more practical and reliable tools for predicting seismic behavior of structures, are extensively studied. Among them, the capacity spectrum method(CSM) is conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper considers a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of mixed building structures without iterative computations, given dynamic property T from stiffness skeleton curve and nonlinear pseudo acceleration A_{y}/g and/or ductility ratio \mu from response spectrum. The nonlinear response history analysis has been performed and analyzed with various earthquakes for estimation of reliability and practicality of NDSM with mixed building structures.

항복후강성계수 변화에 따른 비선형 직접스펙트럼법의 응답특성

박진화,강병두,노필성,김재웅 동아대학교 건설기술연구소 2002 硏究報告 Vol.26 No.1

Most structures are expected to deform beyond the limit of linearly elastic behavior when subjected to strong ground motion. Seismic evaluation of structure requires an estimation of the structural performance in terms of displacement demand imposed by earthquakes on the structure. Nonlinear time history analysis(NTHA) is the most rigorous procedure to compute seismic performance among various inelastic analysis methods. But nonlinear analysis procedures necessitate more practical and reliable tools for predicting seismic behavior of structures. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for MDF(multi degree of freedom) system. The purpose of this paper is to investigate the accuracy and reliability of this method from a point of view of post-yielding stiffness factors.

다양한 구조특성에 따른 비선형 약산법들의 비교

신기영,강병두,김재웅 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)

In performance-based design methods, it is clear that the evaluation of the nonlinear response is required. Some codes proposed the capacity spectrum method(CSM) based on the nonlinear static analysis to determine earthquake induced demand given the structure pushover curve. This procedure is conceptually simple but iterative and time consuming with some errors. The nonlinear direct spectrum method(NDSM) is proposed and studied to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis, especially for shear buildings system. The purpose of this paper is to compare accuracy of approximate nonlinear methods with respect to various structure characteristics.

내진성능평가를 위한 비선형 직접스펙트럼법의 특성

강병두,김재웅 한국지진공학회 2002 한국지진공학회논문집 Vol.6 No.4

성능에 기초한 설계법에서는 비선형 응답산정이 필수적이며, 이를 위한 방법으로는 비선형시각이력해석법, 비선형 정적해석법, 비선형 효과를 고려한 등가선형해석법 등이 있다. 일부 규준에서는 pushover곡선으로부터 작성한 성능스펙트럼과 선형 응답스펙트럼으로부터 작성한 요구스펙트럼으로 이루어진 능력스펙트럼법을 제안하고 있다. 이 방법은 개념적으로는 간단하나 반복과정이 요구되며, 부정확한 결과를 산출하는 경우가 많다. 이에 따라 시행착오적인 등가선형 스펙트럼대신 비선형스펙트럼을 사용하는 방법들에 대한 연구들이 진행되고 있다. 비선형 요구스펙트럼은 표준적 선형 설계스펙트럼으로부터 결정될 수 있으며, 이 방법은 등가선형의 경우보다는 계산과정이 대폭 줄어들기는 하나 아직도 다소의 연산과정이 요구된다. 따라서 본 연구에서는 다자유도계의 구조물에 대한 pushover곡선으로부터 구조물의 진동주기와 항복강도를 구한 다음, 일련의 계산과정을 거치지 않고도, 직접적으로 비선형 최대응답을 구할 수 있는 비선형 직접스펙트럼법(NDSM)을 제시하극 집중질량계의 MDF(다자유도계) 모델에 대해 다양한 지진기록과 제하강성저하지수를 변수로 하여 NDSM의 적용성과 신뢰성을 평가하고자 한다. 본 연구의 결론은 다음과 같다. 1) 다자유도계 구조물에 대한 비선형 직접스펙트럼법에 의한 최대변위 응답은 비선형 시각이력해석법에 의한 응답과 거의 일치하므로 실용적인 방법으로 사료된다. 2) 비선형 직접스펙트럼법과 비선형 시각이력해석에 의해 산정된 죄상층 변위 결과를 비교하면, 항복후강성계수가 0.1, MAD(modal adaptive distribution)에 의한 수평정적하중분폰 그리고 제하강성저하지수가 0.2~O.3일 때 평균오차가 가장 줄어드는 것으로 나타났다.0.2%와 64.3%로 판막재건술을 시행했던 환자에서 높게 나타났으나 두 군 사이의 통계학적 의의는 보이지 않았다. 결론: 건삭파열 및 유두근 파열로 인한 승모판막 폐쇄 부전의 가장 많은 병리조직학적 원인은 비특이적 변성이었다. 또한 판막 폐쇄 부전의 원인이 승모판막의 퇴행성 병변일 경우에 수술적 방법으로서 승모판막 재건술은 그 장기 성적이 양호하고 수술적 결과가 승모판막 치환술과 비교적 우월한 차이를 보이므로 승모판막 폐쇄 부전의 수술적 치료에 있어서 가장 좋은 방법이라 생각한다. 대상 혈관의 정확한 수술 전 평가 등을 통해 중장기 개통률을 향상시킬 수 있다.25^{\circ}C에서 49.30% (76.66mg/kg)로 나타나 주로 25^{\circ}C 이하에서 발현한 것으로 나타났다. 3. 배양온도에서 검지 된 뷰틸산의 량은 6일 동안 돈분에서 1,463.87mg/kg, 계분에서 96.72mg/kg, 우분에서 129.18mg/kg이 발현되었으며 돈분의 경우 93.31%(1,365.95mg/kg)가 25^{\circ}C에서 발현되었고 이 중 87.92%가 3일령, 4일령과 6일령에 집중적으로 나타났다. 계분의 경우 37^{\circ}C 처리구에서 76.60%(74.09 mg/kg)로 발현되었고 이 중 88%가 1일령, 2일령과 5일령에 집중적으로 나타났다. 우분의 경우 61.55%(79.51mg/kg)가 25^{\circ}C에서 발현되었고 이 중 89.6%가 1일령, 3일령과 4일령에 집중적으로 나타났다. 4. 배양온도에서 검지된 이소밸릭산의 량은 6일 동안 돈분에서 6,885.99mg/kg, 계분에서 307.47mg/kg, 우분에서 It has been recognized that the damage control must become a more explicit design consideration. In an effort to develop design methods based on performance it is clear that the evaluation of the nonlinear response is required. The methods available to the design engineer today are nonlinear time history analyses, monotonic static nonlinear analyses, or equivalent static analyses with simulated nonlinear influences. Some building codes propose the capacity spectrum method based on the nonlinear static analysis(pushover analysis) to determine the earthquake-induced demand given by the structure pushover curve. These procedures are conceptually simple but iterative and time consuming with some errors. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for MDF(multi degree of freedom) systems. The purpose of this paper is to investigate the accuracy and confidence of this method from a point of view of various earthquakes and unloading stiffness degradation parameters. The conclusions of this study are as follows; 1) NDSM is considered as practical method because the peak deformations of nonlinear system of MDF by NDSM are almost equal to the results of nonlinear time history analysis(NTHA) for various ground motions. 2) When the results of NDSM are compared with those of NTHA. mean of errors is the smallest in case of post-yielding stiffness factor 0.1, static force by MAD(modal adaptive distribution) and unloading stiffness degradation factor 0.2~0.3.

비선형 약산법에 의한 지진응답평가 비교

신기영,강병두,김재웅 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

In an effort to develop design methods based on performance it is clear that the evaluation of the inelastic response is required. The methods available to the design engineer today are nonlinear time history analyses, or monotonic static nonlinear analyses, or equivalent static analyses with simulated inelastic influences. Some codes proposed the capacity spectrum method based on the nonlinear static(pushover) analysis to determine earthquake-induced demand given the structure pushover curve. This procedure is conceptually simple but iterative and time consuming with some errors. This paper considers a nonlinear direct spectrum method to evaluate seismic performance of structure, without iterative computations, given the structural initial elastic period and yield strength from the pushover analysis, especially for multi degree of freedom structures. The purpose of this paper is to investigate accuracy and confidence of this method from a point of view of various earthquakes.

지진응답평가를 위한 비선형 약산법의 오차해석

박진화,강병두,노필성,김재웅 동아대학교 환경문제연구소 2003 硏究報告 Vol.25 No.2

Recently, a variety of methods are proposed to solve the problems shown in a existing performance-based design of structure. The most accurate one among analysis methods for the performance evaluation of structure is nonlinear time history analysis. However, the approximate analysis methods in aspect of practicality and simplicity are needed. Even though there are linear capacity spectrum method and nonlinear capacity spectrum method through nonlinear static analysis as the representative approximate methods, a repetitive calculation process is consumed and the result is also likely to be inaccurate. Therefore, this research presents nonlinear direct spectrum method which directly enables nonlinear maximum response to derive, after obtaining the yielding strength and the frequency of structure from pushover curves, without going through a series of calculation processes. Also, it is proposed to compare and examine the accuracy and practicality through an example structure.

복합구조물에 대한 비선형 약산법의 신뢰성 평가

김재웅,강병두,배경근 대한건축학회지회연합회 2007 대한건축학회지회연합회 학술발표대회논문집 Vol.2007 No.1

In performance-based seismic design, it is clear that the evaluation of the nonlinear response is required. One of the most accurate earthquake analysis method for the performance evaluation of structure is nonlinear response history analysis, but it is time-consuming and necessitate more efforts. Approximate methods are presented for estimating the capacity of structures while subjecting earthquake ground motions. This is made possible by exploiting the connection between the nonlinear static response of structure and the dynamic response of SDF system whose backbone matches the structure’s pushover curve. The nonlinear direct spectrum method(NDSM) and the uncoupled modal response history analysis(UMRHA) are proposed and studied to evaluate nonlinear response of structures, without iterative computations, given by the structural linear vibration period and yield strength from the pushover analysis. In this study, it is to compare the practicality and the reliability of approximate nonlinear methods with respect to mixed building structures and various earthquakes.