Using integrated displacement method to time-history analysis of steel frames with nonlinear flexible connections

M.A. Hadianfard 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.5

Most connections of steel structures exhibit flexible behaviour under cyclic loading. The flexible connections can be assumed as nonlinear rotational springs attached to the ends of each beam. The nonlinear behaviour of the connections can be considered by suitable moment-rotation relationship. Time-history analysis by direct integration method can be used as a powerful technique to determine the nonlinear dynamic response of the structure. In conventional numerical integration, the response is evaluated for a series of short time increments. The limitations on the size of time intervals can be removed by using Chen and Robinson improved time history analysis method, in which the integrated displacements are used as the new variables in integrated equation of motion. The proposed method permits longer time intervals and reduces the computational works. In this paper the nonlinearity behaviour of the structure is summarized on the connections, and the step by step improved time-history analysis is used to calculate the dynamic response of the structure. Several numerical calculations which indicate the applicability and advantages of the proposed methodology are presented. These calculations illustrate the importance of the effect of the nonlinear behaviour of the flexible connections in the calculation of the dynamic response of steel frames.

Using integrated displacement method to time-history analysis of steel frames with nonlinear flexible connections

Hadianfard, M.A. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.5

Most connections of steel structures exhibit flexible behaviour under cyclic loading. The flexible connections can be assumed as nonlinear rotational springs attached to the ends of each beam. The nonlinear behaviour of the connections can be considered by suitable moment-rotation relationship. Time-history analysis by direct integration method can be used as a powerful technique to determine the nonlinear dynamic response of the structure. In conventional numerical integration, the response is evaluated for a series of short time increments. The limitations on the size of time intervals can be removed by using Chen and Robinson improved time history analysis method, in which the integrated displacements are used as the new variables in integrated equation of motion. The proposed method permits longer time intervals and reduces the computational works. In this paper the nonlinearity behaviour of the structure is summarized on the connections, and the step by step improved time-history analysis is used to calculate the dynamic response of the structure. Several numerical calculations which indicate the applicability and advantages of the proposed methodology are presented. These calculations illustrate the importance of the effect of the nonlinear behaviour of the flexible connections in the calculation of the dynamic response of steel frames.

Nonlinear time history analysis of a pre-stressed concrete containment vessel model under Japan’s March 11 earthquake

Zuo-zhou Zhao,An Duan,Ju Che,Jia-ru Qian,Wei-liang Jin 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.1

To evaluate the behavior of the advanced unbonded pre-stressed concrete containment vessel (UPCCV) for one typical China nuclear power plant under Japan’s March 11 earthquake, five nonlinear time history analysis and a nonlinear static analysis of a 1:10 scale UPCCV structure have been carried out with MSC.MARC finite element program. Comparisons between the analytical and experimental results demonstrated that the developed finite element model can predict the earthquake behavior of the UPCCV with fair accuracy. The responses of the 1:10 scale UPCCV subjected to the 11 March 2011 Japan earthquakes recorded at the MYG003 station with the peak ground acceleration (PGA) of 781 gal and at the MYG013 station with the PGA of 982 gal were predicted by the dynamic analysis. Finally, a static analysis was performed to seek the ultimate load carrying capacity for the 1:10 scale UPCCV.

Assessment of FEMA356 nonlinear static procedure and modal pushover analysis for seismic evaluation of buildings

Hamid Reza Khoshnoud,Kadir Marsono 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.2

Nonlinear static analysis as an essential part of performance based design is now widely used especially at design offices because of its simplicity and ability to predict seismic demands on inelastic response of buildings. Since the accuracy of nonlinear static procedures (NSP) to predict seismic demands of buildings affects directly on the entire performance based design procedure, therefore lots of research has been performed on the area of evaluation of these procedures. In this paper, one of the popular NSP,FEMA356, is evaluated and compared with modal pushover analysis. The ability of these procedures to simulate seismic demands in a set of reinforced concrete (RC) buildings is explored with two level of base acceleration through a comparison with benchmark results determined from a set of nonlinear time history analyses. According to the results of this study, the modal pushover analysis procedure estimates seismic demands of buildings like inter story drifts and hinges plastic rotations more accurate than FEMA356 procedure.

Assessment of FEMA356 nonlinear static procedure and modal pushover analysis for seismic evaluation of buildings

Khoshnoud, Hamid Reza,Marsono, Kadir Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.2

Nonlinear static analysis as an essential part of performance based design is now widely used especially at design offices because of its simplicity and ability to predict seismic demands on inelastic response of buildings. Since the accuracy of nonlinear static procedures (NSP) to predict seismic demands of buildings affects directly on the entire performance based design procedure, therefore lots of research has been performed on the area of evaluation of these procedures. In this paper, one of the popular NSP, FEMA356, is evaluated and compared with modal pushover analysis. The ability of these procedures to simulate seismic demands in a set of reinforced concrete (RC) buildings is explored with two level of base acceleration through a comparison with benchmark results determined from a set of nonlinear time history analyses. According to the results of this study, the modal pushover analysis procedure estimates seismic demands of buildings like inter story drifts and hinges plastic rotations more accurate than FEMA356 procedure.

Seismic Fragility Analysis of a Buried Gas Pipeline Based on Nonlinear Time-History Analysis

이도형,김병화,정성훈,전종수,이태형 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.1

Seismic fragility analysis was performed for API X65, a type of buried gas pipeline that is widely used in Korea. For this purpose, nonlinear time-history analyses were carried out using 15 different analytical models of the pipeline, which represent variations of modeling parameters. The nonlinear Winkler approach was adopted to simulate the soil-pipeline interaction during an earthquake loading. A set of 12 recorded ground motions were selected for the time-history analyses and scaled to represent a range of earthquake intensity levels. Then, fragility functions were developed with respect to the damage states, which are defined in terms of the maximum axial strain of the pipeline. The parameters under consideration for subsequent seismic fragility analyses are the soil conditions, boundary conditions, burial depth, and type of pipeline. Comparative analyses revealed that the first three parameters, most notably the soil conditions, influence the fragility curves, but the last parameter negligibly affects the fragility curves. It is concluded in short that this study is promising to give a useful insight for a rapid seismic performance evaluation of a buried gas pipeline based on nonlinear and fragility analyses.

매설가스배관의 지진 취약도 해석

이도형,전정문,오장균,이두호 한국지진공학회 2010 한국지진공학회논문집 Vol.14 No.5

본 연구에서는 국내에서 널리 사용되고 있는 매설가스배관인 API X65에 대해 지진 취약도 해석을 수행하였다. 이를 위해, 15가지 경우의 배관 해석모델에 대해 12본 세트의 다양한 지진파를 0.1g 등간격으로 스케일링하여 비선형 시간이력해석을 수행한 후, 비선형 시간이력해석으로 얻어진 매설가스배관의 최대 변형률을 이용하여 지진취약도 해석을 수행하였다. 지진 취약도 해석을 위해 본 연구에서는 또한, 지반조건, 단부지점조건, 매립깊이 및 배관형태 등을 변수로 고려하여 지진 취약도 해석을 수행하였다. 지진 취약도 해석결과, 지반조건, 단부지점조건 및 매립깊이는 매설가스배관의 취약도 곡선에 영향을 끼치는 것으로 판단되었고, 특히 지반조건이 미치는 영향은 다른 두 변수에 비해 다소 큰 것을 확인할 수 있었다. 반면에, 배관형태가 취약도 곡선에 미치는 영향은 미미한 것을 알 수 있었다. 종합적으로, 매설가스배관의 지진 취약도 해석과 관련된 연구가 많지 않은 현실을 감안할 때, 본 연구결과는 매설가스배관의 지진 취약성 평가해석에 초석으로 고려되어질 수 있고, 추후 관련분야 연구에 좋은 참고자료가 될 것으로 사료된다. In this paper, earthquake fragility analysis has been comparatively performed with regard to a buried gas pipeline of API X65 which has been widely used in Korea. For this purpose, a nonlinear time-history analyses has been carried out for 15 different analytical models of a buried gas pipeline in terms of the selected 12 sets of earthquake ground motions with 0.1g of scaling interval. Following that, earthquake fragility analyses have been conducted using the maximum axial strain of the pipeline obtained from the nonlinear time-history analyses. Parameters under consideration for subsequent earthquake fragility analyses are soil conditions, end-restraint conditions, burial depth and the type of pipeline. Comparative analyses reveal that whereas the first three parameters influence the fragility curves, particularly soil conditions amongst the three parameters, the last parameter has a little effect on the curves. In all, the present study can be considered as a benchmark fragility analysis of a buried gas pipeline in the absence of an earthquake fragility analysis of the pipeline and thus is expected to be a useful source regarding earthquake fragility analyses of a buried gas pipelines.

Finite Element Modeling and Nonlinear Analysis for Seismic Assessment of Off-Diagonal Steel Braced RC Frame

Keyvan Ramin,Mitra Fereidoonfar 한국콘크리트학회 2015 International Journal of Concrete Structures and M Vol.9 No.1

The geometric nonlinearity of off-diagonal bracing system (ODBS) could be a complementary system to covering and extending the nonlinearity of reinforced concrete material. Finite element modeling is performed for flexural frame, x-braced frame and the ODBS braced frame system at the initial phase. Then the different models are investigated along various analyses. According to the experimental results of flexural and x-braced frame, the verification is done. Analytical assessments are performed in according to three dimensional finite element modeling. Nonlinear static analysis is considered to obtain performance level and seismic behaviour, and then the response modification factors calculated from each model’s pushover curve. In the next phase, the evaluation of cracks observed in the finite element models, especially for RC members of all three systems is performed. The finite element assessment is performed on engendered cracks in ODBS braced frame for various time steps. The nonlinear dynamic time history analysis accomplished in different stories models for three records of Elcentro, Naghan and Tabas earthquake accelerograms. Dynamic analysis is performed after scaling accelerogram on each type of flexural frame, x-braced frame and ODBS braced frame one by one. The base-point on RC frame is considered to investigate proportional displacement under each record. Hysteresis curves are assessed along continuing this study. The equivalent viscous damping for ODBS system is estimated in according to references. Results in each section show the ODBS system has an acceptable seismic behaviour and their conclusions have been converged when the ODBS system is utilized in reinforced concrete frame.

Seismic fragility analysis of a buried pipeline structure considering uncertainty of soil parameters

Yoon, Sungsik,Lee, Do Hyung,Jung, Hyung-Jo Elsevier 2019 The International journal of pressure vessels and Vol.175 No.-

<P><B>Abstract</B></P> <P>In this study, the seismic fragility analysis for a buried gas pipeline of API 5L X65 was performed considering the uncertainty of soil parameters. For this purpose, nonlinear time history analyses were carried out for the pipeline considering soil-pipeline interaction represented by beam on nonlinear Winkler foundation model. A total of 12 input ground motions were employed and four different analytical cases were considered to evaluate the effect of the uncertainty of soil parameters. The four cases proved that uncertainty of soil parameters needs to be taken into account for the assessment of the pipeline response. Using results of the nonlinear time history analyses, seismic fragility analyses were conducted in accordance with three damage states. Analytical predictions indicated that seismic fragility curves with the uncertainty of soil parameters exhibit higher failure probability than those without the uncertainty. It is thus concluded that the present study is promising for the exploration of the seismic fragility analysis considering the uncertainty of soil parameters.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Seismic fragility analysis has been carried out for a buried gas pipeline considering uncertainty of soil parameters. </LI> <LI> Beam on nonlinear-Winkler foundation model was utilized for soil-pipeline interaction. </LI> <LI> An efficient Monte Carlo Simulation employing Latin Hypercube Sampling was adopted. </LI> <LI> Unit-weight has been identified as dominant factor affecting the behavior of pipeline. </LI> <LI> Seismic fragility curve that takes into account the uncertainty of soil parameters was more vulnerable to earthquakes. </LI> </UL> </P>

Comparison Between Static Nonlinear and Time History Analysis Using Flexibility-Based Model for An Existing Structure and Effect of Taking Into Account Soil Using Domain Reduction Method for a Single Media

Belgasmia Mourad,Moussaoui Sabah 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.3

This work is divided into two parts; the first one presents the nonlinear methods of analyses for seismic design of structures. Thefirst method is the nonlinear pushover procedure, which is based on the N2 method. The second method is the classical nonlineartime history analysis. The objective of this paper is to make a comparative study of an existing reinforced concrete building inBonefro, Italy between static nonlinear analysis and time history analysis using flexibility-based finite element, and the sensitivity ofthe time history analyses to the seismic parameters. The second part presents an elegant method called Domain Reduction Method,which takes into account a small adjacent part of subsoil including structure. With this way the size of the problem to be solved issubstantially reduced. All this through Z_Soil; engineering software based on the finite-element method.