The Conservatism of Leak Before Break Analysis in Terms of the Applied Moment at Cracked Section

2016 ◽  
Author(s):  
Yeji Kim ◽  
Young-Jin Oh ◽  
Heung-Bae Park
Keyword(s):  
Time History ◽  
Time History Analysis ◽  
Elastic Behavior ◽  
Plastic Behavior ◽  
Pipe Material ◽  
Linear Elastic ◽  
Pipe Model ◽  
History Analysis ◽  
Comparison Results ◽  
Leak Before Break

In leak before break (LBB) analysis, applied moment at the position of a postulated crack is a key parameter. The current procedures of LBB analysis use the value of design basis loads that are calculated with the assumption that the pipe does not contain a crack and follows the linear elastic behavior. Therefore, this can lead to conservative results of LBB evaluation compared with the case that considers the effect of plastic behavior of cracked pipe on the calculation of the applied moment at the cracked section [2]. This paper aims to quantitatively investigate the conservatism of the existing LBB analysis in terms of the applied moment at the cracked section. The calculation results using the current procedures with linear elastic pipe model without a crack were compared with the results from the cracked pipe analysis. To consider nonlinearity of crack behavior and pipe material, the time history analysis methods that were verified using the simulated seismic pipe system experiment in the IPIRG-2 program were employed. The comparison results indicated that the applied moment at the cracked section decreases when the effect of crack and nonlinear behavior are considered in the analysis. Therefore, the current procedures of LBB analysis are significantly conservative compared with the elastic-plastic time history analysis. Base on this detailed analysis, the additional safety margin can be secured in the LBB analysis.

Improved Explicit Method for Time History Analysis

2007 ◽  
Author(s):  
Shuenn-Yih Chang ◽  
Chiu-Li Huang
Keyword(s):  
Time History ◽  
Time History Analysis ◽  
Conditional Stability ◽  
Explicit Method ◽  
Explicit Integration ◽  
Unconditionally Stable ◽  
Stability Properties ◽  
Linear Elastic ◽  
History Analysis ◽  
Improved Stability

In this paper, an explicit integration method is presented. This method is shown to have the same numerical characteristics as those of the constant average acceleration method for a linear elastic system. This implies that it is unconditionally stable for linear elastic systems. However, it shows very different stability properties for nonlinear systems. In fact, it has conditionally stability for an instantaneous stiffness hardening system while it remains unconditionally stable for an instantaneous stiffness softening system. The conditional stability property is much better than for the Newmark explicit method for instantaneous stiffness hardening systems. Meanwhile, this method involves no iterative procedure in the step-by-step integration. Thus, it is very promising for time history analysis since it is explicit and has improved stability properties.

PERILAKU STRUKTUR BAJA TIPE MRF DENGAN BEBAN LATERAL BERDASARKAN SNI 1726-2012 DAN METODE PERFORMANCE BASED PLASTIC DESIGN (PBPD)

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Nidiasari Jati Sunaryati Eem Ikhsan
Keyword(s):  
Pushover Analysis ◽  
Time History ◽  
Time History Analysis ◽  
Plastic Design ◽  
History Analysis ◽  
Non Linear ◽  
Static Pushover Analysis

Struktur rangka baja pemikul momen merupakan jenis struktur baja tahan gempa yang populer digunakan. Daktilitas struktur yang tinggi merupakan salah satu keunggulan struktur ini, sehingga mampu menahan deformasi inelastik yang besar. Dalam desain, penggunaan metode desain elastis berupa evaluasi non-linear static (Pushover analysis) maupun evaluasi non-linear analisis (Time History Analysis) masih digunakan sebagai dasar perencanaan meskipun perilaku struktur sebenarnya saat kondisi inelastik tidak dapat digambarkan dengan baik. Metode Performance-Based Plastic Design (PBPD) berkembang untuk melihat perilaku struktur sebenarnya dengan cara menetapkan terlebih dahulu simpangan dan mekanisme leleh struktur sehingga gaya geser dasar yang digunakan adalah sama dengan usaha yang dibutuhkan untuk mendorong struktur hingga tercapai simpangan yang telah direncanakan. Studi dilakukan terhadap struktur baja 5 lantai yang diberi beban gempa berdasarkan SNI 1726, 2012 dan berdasarkan metode PBPD. Hasil analisa menunjukkan bahwa struktur yang diberi gaya gempa berdasarkan metode PBPD mencapai simpangan maksimum sesuai simpangan rencana dan kinerja struktur yang dihasilkan lebih baik .

scholarly journals Record-to-record variability and code-compatible seismic safety-checking with limited number of records

2021 ◽  
Author(s):  
Fatemeh Jalayer ◽  
Hossein Ebrahimian ◽  
Andrea Miano
Keyword(s):  
Seismic Hazard ◽  
Linear Time ◽  
Time History ◽  
Time History Analysis ◽  
Seismic Safety ◽  
Hazard Curve ◽  
History Analysis ◽  
Non Linear ◽  
Seismic Hazard Curve ◽  
Cloud Analysis

AbstractThe Italian code requires spectrum compatibility with mean spectrum for a suite of accelerograms selected for time-history analysis. Although these requirements define minimum acceptability criteria, it is likely that code-based non-linear dynamic analysis is going to be done based on limited number of records. Performance-based safety-checking provides formal basis for addressing the record-to-record variability and the epistemic uncertainties due to limited number of records and in the estimation of the seismic hazard curve. “Cloud Analysis” is a non-linear time-history analysis procedure that employs the structural response to un-scaled ground motion records and can be directly implemented in performance-based safety-checking. This paper interprets the code-based provisions in a performance-based key and applies further restrictions to spectrum-compatible record selection aiming to implement Cloud Analysis. It is shown that, by multiplying a closed-form coefficient, code-based safety ratio could be transformed into simplified performance-based safety ratio. It is shown that, as a proof of concept, if the partial safety factors in the code are set to unity, this coefficient is going to be on average slightly larger than unity. The paper provides the basis for propagating the epistemic uncertainties due to limited sample size and in the seismic hazard curve to the performance-based safety ratio both in a rigorous and simplified manner. If epistemic uncertainties are considered, the average code-based safety checking could end up being unconservative with respect to performance-based procedures when the number of records is small. However, it is shown that performance-based safety checking is possible with no extra structural analyses.

Time-History Analysis of a Super-Large Storage Tank Under Seismic Excitation

2013 ◽  
Author(s):  
Fan Bu ◽  
Caifu Qian
Keyword(s):  
Storage Tank ◽  
Time History ◽  
Time History Analysis ◽  
Radial Deformation ◽  
Tank Wall ◽  
History Analysis ◽  
Medium Level ◽  
Wall Deformation ◽  
Slow Progress ◽  
Earthquake Action

In this paper, two finite element models are established for a super-large storage tank with or without a floating roof on the medium level. Time-history analysis with consideration of fluid-solid coupling for the deformation of tank wall and medium sloshing during or after an earthquake is performed with the emphasis on the effects of the floating roof. It is found that the upper part of tank is more sensitive to the earthquake action than the lower part. The wind girders and the reinforcing rings play a big role in limiting the radial deformation of the upper part of the tank wall. The floating roof has little effect on the tank wall deformation, but it is effective in suppressing the medium sloshing during the earthquake. After the earthquake, the radial deformation of the tank wall attenuates quickly, but the sloshing attenuation of the medium presents a slow progress and the floating roof inhibits the sloshing attenuation of the medium.

Nonlinear Dynamic Analysis of the Damping Frame Structure System

2012 ◽  
Vol 594-597 ◽  
pp. 886-890 ◽  
Author(s):  
Gan Hong ◽  
Mei Li ◽  
Yi Zhen Yang
Keyword(s):  
Energy Dissipation ◽  
Seismic Response ◽  
Nonlinear Dynamic ◽  
Time History ◽  
Time History Analysis ◽  
Frame Structure ◽  
Force Model ◽  
Operating Characteristics ◽  
Restoring Force ◽  
History Analysis

Abstract. In the paper, take full account of energy dissipation operating characteristics. Interlayer shear-frame structure for the analysis of the Wilson-Θmethod ELASTOPLASTIC schedule, the design of a nonlinear dynamic time history analysis procedure. On this basis, taking into account the restoring force characteristics of the energy dissipation system, the inflection point in the restoring force model treatment, to avoid a result of the calculation results of distortion due to the iterative error. A frame structure seismic response time history analysis results show that: the framework of the energy dissipation significantly lower than the seismic response of the common framework, and its role in the earthquake when more significant.

Elastic-Plastic Time History Analysis of MR Damping Structure Based on LQG Algorithm

2016 ◽  
Vol 858 ◽  
pp. 145-150
Author(s):  
Yu Liang Zhao ◽  
Zhao Dong Xu
Keyword(s):  
Optimal Control ◽  
Time History ◽  
Mr Damper ◽  
Time History Analysis ◽  
Control Force ◽  
Control Effect ◽  
Damping Force ◽  
Optimal Control Strategy ◽  
Elastic Plastic ◽  
History Analysis

This paper discussed an elastic-plastic time-history analysis on a structure with MR dampers based on member model, in which the elastoplastic member of the structure is assumed to be single component model and simulated by threefold line stiffness retrograde model. In order to obtain better control effect, Linear Quadratic Gaussian (LQG) control algorithm is used to calculate the optimal control force, and Hrovat boundary optimal control strategy is used to describe the adjustable damping force range of MR damper. The effectiveness of the MR damper based on LQG algorithm to control the response of the structure was investigated. The results from numerical simulations demonstrate that LQG algorithm can effectively improve the response of the structure against seismic excitations only with acceleration feedback.

A Study on Time History Analysis of Multi-support Excitement by Input Methods

2021 ◽  
Vol 31 (5) ◽  
pp. 543-550
Author(s):  
Chi Woong Ra ◽  
Eun-Ho Lee ◽  
Chang Kyun Lee ◽  
JinWoo Im ◽  
No-Cheol Park
Keyword(s):  
Time History ◽  
Time History Analysis ◽  
History Analysis

Seismic performance of Greater Jakarta LRT with added lead rubber bearing using non-linear time history analysis

2021 ◽  
Author(s):  
Iswandi Imran ◽  
Marie Hamidah ◽  
Tri Suryadi ◽  
Hasan Al-Harris ◽  
Syamsul Hidayat
Keyword(s):  
Linear Time ◽  
Time History ◽  
Time History Analysis ◽  
Performance Level ◽  
Structural Performance ◽  
Isolation System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
History Analysis ◽  
Seismic System

<p>In order to overcome stringent seismic requirement in the new Greater Jakarta Light Rail Transit Project, a breakthrough seismic system shall be chosen to obtain expected structural performance. This seismic system shall be designed to provide operational performance level after strong earthquake events. To achieve the criteria, seismic isolation system using Lead Rubber Bearings is chosen. With this isolation system, Greater Jakarta LRT has become the first seismically isolated infrastructure and apparently an infrastructure with the largest numbers of LRBs in one single project in Indonesia. More than 10.400 Pcs LRBs are used for the first phase of the construction and the numbers will be certainly increased in the next phase of the construction. To evaluate the structural performance, non-linear time history analysis is used. A total of 3 pair matched ground motions will be used as the input for the response history analysis. The ability of the lead rubber bearing to isolate and dissipate earthquake actions will determine its structural performance level. This will be represented by the nonlinear hysteretic curves obtained throughout the earthquake actions.</p>

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