scholarly journals Seismic Fragility Curves for Performance of Semi-rigid Connections of Steel Frames

2021 ◽  
Vol 7 (7) ◽  
pp. 1112-1124
Author(s):  
Mohamed Saadi ◽  
Djarir Yahiaoui ◽  
Noureddine Lahbari ◽  
Bouzid Tayeb
Keyword(s):  
Seismic Performance ◽  
Fragility Curves ◽  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Skilled Workers ◽  
Rigid Frame ◽  
Rigid Connection ◽  
Rigid Joints ◽  
Static Pushover Analysis

A steel frame with a semi-rigid connection is one of the most widely used structural systems in modern construction. These systems are cheap to make, require less time to construct and offer the highest quality and reliable construction quality without the need for highly skilled workers. However, these systems show greater natural periods compared to their perfectly rigid frame counterparts. This causes the building to attract low loads during earthquakes. In this research study, the seismic performance of steel frames with semi-rigid joints is evaluated. Three connections with capacities of 50, 70 and 100% of the beam’s plastic moment are studied and examined. The seismic performance of these frames is determined by a non-linear static pushover analysis and an incremental dynamic analysis leading finally to the fragility curves which are developed. The results show that a decrease in the connection capacity increases the probability of reaching or exceeding a particular damage limit state in the frames is found. Doi: 10.28991/cej-2021-03091714 Full Text: PDF

Comparison of steel frames with RWS and WFP beam-to-column connections through seismic fragility analysis

2020 ◽  
pp. 136943322097728
Author(s):  
Haoran Yu ◽  
Weibin Li
Keyword(s):  
Limit State ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Fragility Analysis ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Fe Modelling ◽  
Collapse Resistance ◽  
Seismic Collapse ◽  
Probabilistic Seismic Demand

Reduced web section (RWS) connections and welded flange plate (WFP) connections can both effectively improve the seismic performance of a structure by moving plastic hinges to a predetermined location away from the column face. In this paper, two kinds of steel frames—with RWS connections and WFP connections—as well as different frames with welded unreinforced flange connections were studied through seismic fragility analysis. The numerical simulation was conducted by using multiscale FE modelling. Based on the incremental dynamic analysis and pushover analysis methods, probabilistic seismic demand analysis and seismic capability analysis were carried out, respectively. Finally, combined with the above analysis results, probabilistic seismic fragility analysis was conducted on the frame models. The results showed that the RWS connection and WFP connection (without double plates) have little influence on reducing the maximum inter-storey drift ratio under earthquake action. RWS connections slightly reduce the seismic capability in non-collapse stages and improve the seismic collapse resistance of a structure, which exhibits good structural ductility. WFP connections can comprehensively improve the seismic capability of a structure, but the seismic collapse resistance is worse than that of RWS connections when the structure has a large number of storeys. The frame with WFP connections has a lower failure probability at every seismic limit state, while the frame with RWS connections sacrifices some of its structural safety in non-collapse stages to reduce the collapse probability.

scholarly journals Seismic Performance of Partially Dismantled Buildings

2018 ◽  
Vol 13 (1) ◽  
pp. 69-77
Author(s):  
Jagat Kumar Shrestha
Keyword(s):  
Seismic Performance ◽  
Residential Buildings ◽  
Pushover Analysis ◽  
Seismic Evaluation ◽  
The Road ◽  
Nonlinear Static ◽  
The Comparative Study ◽  
Road Widening ◽  
Static Pushover Analysis ◽  
Storey Building

 This study carries out the comparative study of Seismic Performance of residential buildings after partial dismantling for road widening works in Kathmandu city. Two types of buildings were taken for the study, i.e. 4 storey building and 6 storey building. The Buildings were assessed for bare frames. The detail level of the seismic evaluation was carried out by preparing 3-D modeling of the buildings in SAP2000 software by nonlinear static pushover analysis. The capacity of the buildings has been found significantly decreased after the partial dismantling of the building due to the road widening works. The behavior of buildings has been found like a strong beam and weak column mechanism.Journal of the Institute of Engineering, 2017, 13(1): 69-77

Risk-Based Seismic Performance Assessment of Pressurized Piping Systems Considering Ratcheting

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
A. Ravi Kiran ◽  
G. R. Reddy ◽  
M. K. Agrawal
Keyword(s):  
Performance Assessment ◽  
Seismic Performance ◽  
Fragility Curves ◽  
Limit State ◽  
Frequency Variation ◽  
Seismic Load ◽  
Piping System ◽  
Seismic Performance Assessment ◽  
Limit States ◽  
Piping Systems

Abstract A procedure is described for risk-based seismic performance assessment of pressurized piping systems considering ratcheting. The procedure is demonstrated on a carbon steel piping system considered for OECD-NEA benchmark exercise on quantification of seismic margins. Initially, fragility analysis of the piping system is carried out by considering variability in damping and frequency. Variation in damping is obtained from the statistical analysis of the damping values observed in earlier experiments on piping systems and components. The variation in ground motion is considered by using 20 strong motion records of the intraplate region. Floor motion of a typical reactor building of a nuclear power plant under these actual earthquake records is evaluated and applied to the piping system. The performance evaluation of the piping system in terms of ratcheting is carried out using a numerical approach, which was earlier validated with shake table ratcheting tests on piping components and systems. Three limit states representing performance levels of the piping system under seismic load are considered for fragility evaluation. For each limit state, probability of exceedance at different levels of floor motion is evaluated to generate a fragility curve. Subsequently, the fragility curves of the piping systems are convoluted with hazardous curves for a typical site to obtain the risk in terms of annual probability of occurrence of the performance limits.

scholarly journals Seismic Performance Evaluation of a Fully Integral Concrete Bridge with End-Restraining Abutments

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Byung H. Choi ◽  
Lorenz B. Moreno ◽  
Churl-Soo Lim ◽  
Duy-Duan Nguyen ◽  
Tae-Hyung Lee
Keyword(s):  
Seismic Performance ◽  
Lateral Displacement ◽  
Pushover Analysis ◽  
Frame Structure ◽  
Performance Criteria ◽  
Elastic Behavior ◽  
Integral Bridge ◽  
Nonlinear Static ◽  
Static Pushover Analysis ◽  
Nonlinear Static Pushover Analysis

A fully integral bridge that is restrained at both ends by the abutments has been proposed to form a monolithic rigid frame structure. Thus, the feasible horizontal force effect due to an earthquake or vehicle braking is mainly prevented by the end-restraining abutments. In a recent study, a fully integral bridge with appropriate end-restraining abutment stiffness was derived for a multispan continuous railroad bridge based on linear elastic behavior. Therefore, this study aims to investigate the nonlinear behavior and seismic capacity of the fully integral bridge and then to assess the appropriate stiffness of the end-restraining abutment to sufficiently resist design earthquake loadings through a rigorous parametric study. The finite element modeling and analyses are performed using OpenSees. In order to obtain the force-deflection curves of the models, nonlinear static pushover analysis is performed. It is confirmed that the fully integral bridge prototype in the study meets the seismic performance criteria specified by Caltrans. The nonlinear static pushover analysis results reveal that, due to the end-restraining effect of the abutment, the lateral displacement of the fully integral bridge is reduced, and the intermediate piers sustain less lateral force and displacement. Then, the sectional member forces are well controlled in the intermediate piers by a proper application of the end-restraining abutments.

scholarly journals Study on the Development of Seismic Fragility of Steel SMRF

2021 ◽  
Vol 9 (11) ◽  
pp. 1472-1477
Author(s):  
Swapnali Sachin Kulkarni
Keyword(s):  
Vulnerability Assessment ◽  
Fragility Curves ◽  
Pushover Analysis ◽  
Probability Of Failure ◽  
Fragility Analysis ◽  
Analysis Methods ◽  
Nonlinear Static ◽  
Static Pushover Analysis ◽  
Slight Damage ◽  
Nonlinear Static Pushover Analysis

Abstract: Vulnerability assessment of the structure is the most important and wide area of research which requires more input from the engineers and seismologist. The seismic vulnerability assessment of the structure can be evaluated by developing Fragility curves. Fragility curves shows the conditional probability of the structure exceeding the particular performance limit of the given damage state during strong ground motions. Fragility curves can be developed for different parameters like spectral displacement (Sd), spectral acceleration (Sa) Peak ground acceleration (PGA) , Inter storey drift ratio (IDR) etc. This paper describes about the different methods used in deriving the Fragility curves like conventional methods, Nonlinear Dynamic analysis methods and Nonlinear Static analysis methods. Also the fragility analysis of 5 Storied Steel Moment Resisting Frame (SMRF) has been carried out based on the parameters suggested by HAZUS M.H 2.1. Nonlinear static pushover analysis of the frame has been carried out in ETABS2016. Fragility curves are developed based on the pushover analysis results. The damage states defined as per HAZUS are Slight damage (SD), Moderate damage (MD) Extensive damage (ED) and Complete damage (CD). After carrying out the fragility analysis for the steel SMRF, it has been found out that, as the spectral displacement increases probability of failure for the slight damage of the structure is very high and the probability of failure for the complete damage is very low. Hence the probability of failure of the structure reduces from slight damage to complete damage. Keywords: Fragility curves, vulnerability assessment, Nonlinear static pushover analysis, HAZUS M.H 2.1.

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 .

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