Cyclic Pushover Method for Seismic Assessment under Multiple Earthquakes

2019 ◽  
Vol 35 (4) ◽  
pp. 1541-1558
Author(s):  
Alexander Kagermanov ◽  
Robin Gee
Keyword(s):  
Pushover Analysis ◽  
Central Italy ◽  
Time History ◽  
Degree Of Freedom ◽  
Nonlinear Time History Analysis ◽  
Seismic Performance Assessment ◽  
Practical Applications ◽  
Rc Frames ◽  
Cyclic Degradation ◽  
Nonlinear Time History

A new method for the seismic performance assessment of structures subjected to a sequence of earthquakes is presented. The method is based on the cyclic pushover analysis of a multi-degree-of-freedom (MDOF) structure. Instead of relying on a single value of target displacement, as in the case of monotonic push-over methods, a simplified cyclic displacement history is derived from an equivalent single-degree-of-freedom (SDOF) structure for the assessment of the MDOF one. The main advantage of the method is that it directly accounts for cyclic degradation of the actual MDOF system while retaining the simplicity and computational efficiency of SDOF systems for displacement demand evaluation, thus making it attractive for practical applications. The procedure is exemplified in detail using ductile and nonductile reinforced concrete (RC) frames as benchmark structures subjected to the Central Italy sequence. Further comparison with fully nonlinear time-history analysis and code-prescribed monotonic pushover is provided in order to assess the accuracy and advantages of the proposed method.

Investigation of Damages in RC Frames Under Near Field Earthquakes Using a Damage Index

2016 ◽  
Vol 16 (02) ◽  
pp. 1450094 ◽  
Author(s):  
Seyed Morteza Zinati Yazdi ◽  
Mohammad Taghi Kazemi
Keyword(s):  
Near Field ◽  
Damage Index ◽  
Time History ◽  
General Rule ◽  
Nonlinear Time History Analysis ◽  
Far Field ◽  
Moment Frames ◽  
Moment Frame ◽  
Rc Frames ◽  
Nonlinear Time History

Heavy damages on structures caused by near field earthquakes in recent years has brought serious attention to this problem. An examination of previous records has shown significant differences for near field earthquakes, including a large energy pulse, unlike far field earthquakes. But as a general rule, the effects of near field earthquakes have been ignored in most building codes. The purpose of this paper is to investigate the effect of near field earthquakes on reinforced concrete (RC) moment frames. To achieve this goal, the Erduran damage index, an efficient way to calculate damage, was employed to analyze two 4- and 8-story RC moment frame buildings. The buildings with moderate and high ductility were designed by the strength criteria. Seven pairs of near field and far field earthquakes were scaled and used for dynamic nonlinear time history analysis. Using Erduran’s beam and column damage index, respectively, based on rotation and drift, the results from both near and far field earthquakes were compared. Moreover, for better assessment, 4-story buildings were evaluated from the performance based viewpoint of design. We observe from the results that most of the components of the structures under near field earthquakes sustained severe damages and in some cases even component failure. Components of the structures under near field earthquakes suffered from 30% more of damage, on average, than that under far field earthquakes.

Strengthening Research in the Longitudinal Frames of Prefabricated Structures with Viscous Dampers

2013 ◽  
Vol 671-674 ◽  
pp. 782-785
Author(s):  
Bin He ◽  
Jin Lai Pang ◽  
Cheng Qing Liu
Keyword(s):  
Seismic Performance ◽  
Pushover Analysis ◽  
Vertical Direction ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Viscous Dampers ◽  
Existing Building ◽  
Concrete Frame ◽  
Uniform Drift ◽  
Nonlinear Time History

For the lack of research in the longitudinal frame of prefabricated structure for its weak lateral stiffness, pushover analysis is conducted to evaluate the seismic performance of a fabricated concrete frame. Based on case study, the strengthening strategies with viscous dampers are analyzed. In view of the undesirable drift distribution and failure mode in the existing building, it is believed that arrangement of dampers should be designed to attain a uniform drift distribution. Based on the nonlinear time history analysis method, the strategy of damper allocation in vertical direction of the structure is investigated .Results indicate that a proper design might be attained based on the property of existing system, leading to a uniform drift distribution and better seismic performance.

scholarly journals Analisis Kinerja Bangunan Rangka Baja dengan Bresing Tahan Tekuk terhadap Beban Gempa

2021 ◽  
Vol 6 (2) ◽  
pp. 98
Author(s):  
Ilham Ilham
Keyword(s):  
Pushover Analysis ◽  
Time History ◽  
Steel Structures ◽  
Time History Analysis ◽  
Nonlinear Time History Analysis ◽  
Structural Performance ◽  
History Analysis ◽  
Immediate Occupancy ◽  
Nonlinear Time History ◽  
Modal Pushover

ABSTRAKPenggunaan bresing tahan tekuk dapat menjadi solusi atas kebutuhan struktur tahan gempa di Indonesia. Disipasi energi pada elemen bresing tahan tekuk dilakukan melalui kinerja plastifikasi bagian inti bresing akibat beban tarik dan tekan. Penelitian ini berisi kajian kinerja dari bangunan rangka baja beraturan dengan bresing tahan tekuk (BRB) dengan variasi level ketinggian lantai yaitu 3 lantai, 8 lantai dan 15 lantai. Analisis struktur 3D dilakukan dengan dua prosedur analisis yaitu modal pushover dan nonlinear time history pada program ETABS. Hasil analisis menunjukkan bahwa pemilihan elemen BRB sangat mempengaruhi kinerja struktur, yang terlihat dari pola drift yang terjadi. Untuk struktur beraturan dengan berbagai ketinggian, tingkat kinerja struktur dengan BRB cukup baik, yaitu Immediate Occupancy (IO) akibat beban gempa rencana. Plastifikasi hanya terjadi pada BRB, dan kelelehan pada balok mulai terbentuk sampai mekanisme keruntuhan terjadi. Hasil modal pushover dengan nonlinear time history pada bangunan 15 lantai yang cukup mirip menunjukkan bahwa modal pushover dapat digunakan untuk memprediksi kinerja struktur BRB yang beraturan.Kata kunci: kinerja struktur, bresing tahan tekuk, immediate occupancy, modal pushover, nonlinear time history ABSTRACTBuckling restrained braces (BRB) can be an alternative solution for earthquake resistant steel structure in Indonesia. The energy dissipation for buckling restrained elements is conducted through yielding of the core due to tension or compression forces. This study presents an evaluation of the structural performance of steel structures with BRB varying in heights, 3-story, 8-story and 15-story. The 3D structural analysis was carried out with ETABS software using 2 methods, Modal Pushover and Nonlinear Time History. The results shows that the selection of BRB elements greatly affected the structural performance, showed by the drift pattern. For regular structures with variation in heights, structures with BRB behaved satisfactory under the design load with the performance level of Immediate Occupancy (IO). Yielding was limited to BRB members, and afterwards the yielding occurred on beams until collapse. The results of modal pushover and time history analysis for 15-story structure are similar, thus modal pushover can be used to predict the performance of regular structural system with BRB.Keywords: structural performance, buckling restrained brace, immediate occupancy, modal pushover analysis, nonlinear time history analysis

scholarly journals A Wavelet-based Approach for Truncating Pulse-like Records

2021 ◽  
Author(s):  
Vicky Dimakopoulou ◽  
Michalis Fragiadakis ◽  
Ioannis Taflampas
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Time History ◽  
Response Spectra ◽  
Degree Of Freedom ◽  
Seismic Performance Assessment ◽  
Analysis And Design ◽  
Nonlinear Time History Analyses ◽  
Ground Motion Records ◽  
Nonlinear Time History

Abstract The seismic performance assessment of structures using truncated pulse-like ground motion records is discussed. It is shown that it is possible to truncate pulse-like signals using a novel wavelet-based definition that identifies the duration of the predominant velocity pulse. The truncated time history can efficiently reproduce the increased seismic demand that near-field records typically produce. Substituting the original ground motion with the truncated signal, significantly accelerates structural analysis and design. The truncated signal is the part of the original accelerogram that coincides with the duration of the predominant pulse, which is identified using a wavelet-based procedure, previously proposed by the authors. Elastic and inelastic response spectra and nonlinear time history analyses for SDOF (single-degree-of-freedom) systems are first studied. Subsequently a nine-storey steel frame is examined in order to demonstrate the performance of the proposed approach on a multiple-degree-of-freedom system. The proposed approach is found very efficient for pulse-like ground motions, while it is also sufficient for many records that are not characterized as such.

Modal Superposition Technique to Predict the Seismic-Pushover Load for Jacket-Type Structures

2002 ◽  
Author(s):  
Kanthi Srirengan ◽  
Partha Chakrabarti ◽  
Rupak Ghosh
Keyword(s):  
Response Spectrum ◽  
Pushover Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Elastic Response ◽  
Preliminary Evaluation ◽  
Inelastic Behavior ◽  
Linear Superposition ◽  
Linear Elastic ◽  
Nonlinear Time History

Two novel methods namely the Dominant Modes method and the All Modes method to predict the seismic-pushover load for the jacket-type structures are presented. Both of these methods are based on the linear superposition of the modal reactions. As a preliminary evaluation, the linear elastic response of a jacket structure subjected to seismic-pushover loads is compared with that obtained from the response spectrum analysis. Furthermore, the nonlinear inelastic behavior obtained from the seismic-pushover analysis is compared with that obtained from the nonlinear time-history analysis, for a portal frame subjected to El Centro earthquake motion. When more than one mode is dominant in an excitation direction, both the linear elastic and the nonlinear inelastic responses obtained using the loads generated from the All Modes method are representative of the reference solutions.

A Drift Pushover Analysis Procedure for Estimating the Seismic Demands of Buildings

2014 ◽  
Vol 30 (4) ◽  
pp. 1601-1618 ◽  
Author(s):  
Arash Sahraei ◽  
Farhad Behnamfar
Keyword(s):  
Lateral Displacement ◽  
Plastic Hinge ◽  
Pushover Analysis ◽  
Time History ◽  
Relative Displacement ◽  
Analysis Procedure ◽  
New Method ◽  
Nonlinear Time History Analysis ◽  
Displacement Based ◽  
Nonlinear Time History

Relative displacement is a parameter that has a very high correlation with damage. The objective of this article is to develop an analysis procedure founded on the displacement-based seismic design methodology. Generalized interstory drift spectrum is applied as an essential tool in this new method called drift pushover analysis. In order to evaluate the behavior of structures, three demand parameters—lateral displacement, story shear, and plastic hinge rotation—are computed with conventional pushover analysis (CPA), modal pushover analysis (MPA), and drift pushover analysis (DPA), and are compared with those of the nonlinear time history analysis (NTA). It is observed that the new method, DPA, predicts the peak response measures more precisely and with less effort than the other nonlinear pushover procedures investigated in this study.

scholarly journals Special Moment Resistant Steel Buildings

2021 ◽  
pp. 444-448
Author(s):  
Deepan Dev B ◽  
Dr V Selvan
Keyword(s):  
Pushover Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Building Structures ◽  
Braced Frames ◽  
Steel Buildings ◽  
Braced Frame ◽  
Moment Resisting ◽  
Frame Systems ◽  
Nonlinear Time History

The seismic response of special moment-resisting frames (SMRF), buckling restrained braced (BRB) frames and self-centering energy dissipating (SCED) braced frames is compared when used in building structures many stories in height. The study involves pushover analysis as well as 2D and 3D nonlinear time history analysis for two ground motion hazard levels. The SCED and BRB braced frames generally experienced similar peak interstory drifts. The SMRF system had larger interstory drifts than both braced frames, especially for the shortest structures. The SCED system exhibited a more uniform distribution of the drift demand along the building height and was less prone to the biasing of the response in one direction due to P-Delta effects. The SCED frames also had significantly smaller residual lateral deformations. The two braced frame systems experienced similar interstory drift demand when used in torsional irregular structures.

scholarly journals Seismic assessment of tall RC frames with hybrid friction damper and SMA designed by PBPD method

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
F. Norouzi ◽  
H. Nasebaradi ◽  
M. Jamshidi
Keyword(s):  
Design Method ◽  
Time History ◽  
Hysteretic Behavior ◽  
Nonlinear Time History Analysis ◽  
Friction Damper ◽  
High Rise ◽  
Rc Frames ◽  
Lateral Strength ◽  
Residual Deformations ◽  
Nonlinear Time History

In this study, a new lateral load resisting system for high-rise (Reinforced Concrete) RC frames is proposed, which includes friction damper-superelastic SMA wires. The proposed SMA-friction damper can not only regulate the mechanism of frictional energy dissipation components with its self-centering SMA wires according to the design method based on the proposed performance, which is able to provide a hysteretic behavior and high self-centering capacity with the lowest SMA consumption but also has some advantages such as simple configuration and economic application. In this paper, two high-rise 18 and 22-story RC frames were designed in two design modes of common and with the proposed damper. The nonlinear time history analysis subjected to 10 far-field earthquakes performed in Opensees software. The results of the analyses showed that using the proposed SMA-friction damper, in addition to the effective increase in ductility, lateral stiffness and lateral strength, provided an excellent self-centering capacity, which resulted to the significant reduction in the maximum drift and the residual deformations in the structure.

scholarly journals Prediction of the Maximum Seismic Member Force in a Superstructure of a Base-Isolated Frame Building by using Pushover Analysis

Buildings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 201 ◽  
Author(s):  
Fujii
Keyword(s):  
Pushover Analysis ◽  
Time History ◽  
Time History Analysis ◽  
Nonlinear Time History Analysis ◽  
Second Stage ◽  
Frame Building ◽  
History Analysis ◽  
Frame Buildings ◽  
Dynamic Time ◽  
Nonlinear Time History

It is essential for the seismic design of a base-isolated building that the seismic response of the superstructure remains within the elastic range. The evaluation of the maximum seismic member force in a superstructure is thus an important issue. The present study predicts the maximum seismic member force of five- and fourteen-story reinforced concrete base-isolated frame buildings adopting pushover analysis. In the first stage of the study, the nonlinear dynamic (time-history) analysis of the base-isolated frame buildings is carried out, and the nonlinear modal responses of the first and second modes are calculated from pushover analysis results. In the second stage, a set of pushover analyses is proposed considering the combination of the first and second modal responses, and predicted maximum member forces are compared with the nonlinear time-history analysis results. Results show that the maximum member forces predicted in the proposed set of pushover analyses are satisfactorily accurate, while the results predicted considering only the first mode are inaccurate.

Development of Fragility Curves for Multi-Span RC Bridges using Generalized Pushover Analysis

2019 ◽  
Author(s):  
Camilo Perdomo ◽  
Ricardo Monteiro ◽  
Halûk Sucuoğlu
Keyword(s):  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Pushover Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Engineering Practice ◽  
Nonlinear Analyses ◽  
History Analysis ◽  
Nonlinear Time History ◽  
Existing Bridges

<p>Over the past few decades, fragility curves became a powerful tool for the seismic vulnerability assessment of structures. There are several available analytical procedures for calculating fragility curves, using both static and dynamic nonlinear analyses. In this study, a nonlinear static method, based on Generalized Pushover Analysis (GPA), is implemented for the development of analytical fragility curves of reinforced concrete (RC) bridges. The relative accuracy of the GPA algorithm, when applied to a large number of existing bridges, is evaluated through the comparison with the results from Nonlinear Time History Analysis (NTHA). Results indicate that GPA provides a good estimation of the fragility curves with respect to NTHA. The added computational demand of the GPA algorithm in terms of the number of analyses pays off in terms of accuracy while keeping the simplicity of a non-adaptive conventional pushover algorithm, which is desirable in engineering practice.</p>

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