Seismic Ratchetting of Single-Degree-of-Freedom Steel Bridge Columns

2018 ◽  
Vol 763 ◽  
pp. 295-300 ◽  
Author(s):  
Khaled Saif ◽  
Chin Long Lee ◽  
Trevor Yeow ◽  
Gregory A. MacRae
Keyword(s):  
Time History ◽  
Steel Structures ◽  
Bridge Columns ◽  
Steel Bridge ◽  
Axial Loads ◽  
Maximum Displacement ◽  
Residual Displacements ◽  
Average Maximum ◽  
Force Reduction ◽  
Nonlinear Time History

Nonlinear time history analyses of SDOF bridge columns with elasto-plastic flexural behaviour which are subject to eccentric gravity loading are conducted to quantify the effect of ratchetting. Peak and residual displacements were used as indicators of the degree of ratchetting. The effects of member axial loads and design force reduction factors were also investigated. It was shown that displacement demands increased with increasing eccentric moment. For eccentric moment of 30% of the yield moment, the average maximum and residual displacements increase by 4.2 and 3.8 times the maximum displacement, respectively, which the engineers calculate using static methods without considering ratchetting effect. Design curves for estimating the displacement demands for different eccentric moments are also developed. The current NZ1170.5 (2016) provisions were found to be inadequate in estimating the maximum displacement for steel structures, and hence, new provisions for steel structures should be presented.

scholarly journals The Effect of Long Duration Earthquakes on the Overall Seismic Behavior of Steel Structures Designed According to Eurocode 8 Provisions

Vibration ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 464-477
Author(s):  
Panagiota Katsimpini ◽  
Foteini Konstandakopoulou ◽  
George A. Papagiannopoulos ◽  
Nikos Pnevmatikos ◽  
George D. Hatzigeorgiou
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Steel Structures ◽  
Eurocode 8 ◽  
Steel Buildings ◽  
Long Duration ◽  
Base Steel ◽  
Fixed Base ◽  
Permanent Settlement ◽  
Nonlinear Time History

Premature and simultaneous buckling of several steel braces in steel structures due to the prolonged duration of a seismic motion is one of the issues that must be addressed in the next version of Eurocode 8. In an effort to contribute towards the improvement of the seismic design provisions of Eurocode 8, an evaluation of the overall behavior of some steel building-foundation systems under the action of long duration seismic motions is performed herein by means of nonlinear time-history seismic analyses, taking into account soil–structure interaction (SSI) effects. In particular, the maximum seismic response results—in terms of permanent interstorey drifts, overturning moments and base shears of the steel buildings as well as of the permanent settlement and tilting of their foundations—are computed. It is found that the seismic performance of steel buildings when subjected to long duration seismic motions is: (i) acceptable for the two and five-storey fixed base steel buildings and for the two-storey steel buildings with SSI effects included; (ii) unacceptable for the eight-storey fixed base steel buildings and for the five and eight-storey steel buildings with SSI effects included. In all cases of steel buildings with SSI effects included, the seismic performance of the mat foundation, as expressed by the computed values of residual settlement and tilting, is always acceptable.

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

Seismic Performance and Effects of Different Joint Shapes for Unbonded Precast Segmental Bridge Columns

2016 ◽  
Vol 32 (4) ◽  
pp. 427-433
Author(s):  
H.-L. Wang ◽  
S.-W. Liu ◽  
Z. Zhang
Keyword(s):  
Seismic Performance ◽  
Residual Deformation ◽  
Time History ◽  
Bridge Columns ◽  
Nonlinear Time History Analysis ◽  
Backbone Curve ◽  
Coulomb’S Friction ◽  
Plane Contact ◽  
Nonlinear Time History ◽  
Segmental Bridge

AbstractTo study the seismic performance and the effects of different joint shapes for unbonded precast segmental bridge columns under low-reversed cyclic loading, two 3-D finite element (FE) models respectively using plane-contact joints and shear resistant joints were established. In the FE models, the mechanical behaviors of concrete and tendons were respectively described by the damage-plastic model and the bilinear model, and the contact criteria was based on Coulomb's Friction. The results of nonlinear time history analysis showed that the deformation of the columns was mainly composed of alternately open-closed joints, and the failure of the column was mainly caused by concrete crush on the bottom segment. Compared with two model's hysteresis loop, backbone curve, ductility and residual deformation, it was found that the column with shear resistant joints had longer stable period of strength, better ductility, and smaller residual displacement than the column with plane-contact joints, so it had better seismic performance.

Seismic performance of ribbed bracing system in passive control of structures

2015 ◽  
Vol 23 (18) ◽  
pp. 2926-2941 ◽  
Author(s):  
Ali Arzeytoon ◽  
Ali Akbar Golafshani ◽  
Vahab Toufigh ◽  
Hossein Mohammadi
Keyword(s):  
Passive Control ◽  
Compressive Force ◽  
Time History ◽  
Seismic Intensity ◽  
Nonlinear Time History Analysis ◽  
Concentrically Braced Frames ◽  
Maximum Displacement ◽  
Hysteretic Energy ◽  
Bracing System ◽  
Nonlinear Time History

In this article, a novel passive control system, ribbed bracing system (RBS), has been proposed to deal with the buckling problem. RBS is a bracing system with a simple mechanism that can be installed in braces as a supplemental part. The behavior of RBS is similar to that of conventional braces under tensile loading. However, under compressive force, it endures an insignificant force and prevents the braces from buckling through length reduction. In addition, seismic damage is concentrated in the bracing system of the structures equipped with RBS, decreasing the dissipated hysteretic energy in other structural members. There are two different mechanisms for RBS: 1) completely-closed RBS (CC-RBS) and 2) self-centering RBS (SC-RBS). The concept and mechanics of RBS have been verified by the results obtained from cyclic testing and numerical analysis of RBS specimens. In this research, after describing the mechanical configuration of RBS, nonlinear time history analysis has been conducted on 3-story and 6-story concentrically braced frames subjected to different seismic intensity levels, design basis earthquakes (DBE), and maximum considered earthquakes (MCE). The analyses have been performed on different types of bracing systems as follows: SC-RBS, CC-RBS, and Buckling Restrained Braces (BRB). The results show that SC-RBS frames have negligible residual story drifts, and maximum displacement in CC-RBS is slightly lower than that of BRB. Additionally, distribution of input energy into the structure was considered and showed that RBS frames demonstrate a high hysteretic energy dissipation, which results in lower demands in other structural elements.

scholarly journals Investigation of Behaviors of Concrete Shear Wall in High-Rise Steel Buildings

2018 ◽  
Vol 7 (3.2) ◽  
pp. 135
Author(s):  
Hajiyev Mukhlis Ahmad ◽  
Hasan Dabbaghasadollahi Poor
Keyword(s):  
Time History ◽  
Shear Walls ◽  
Steel Structures ◽  
Shear Wall ◽  
Target Point ◽  
Steel Buildings ◽  
High Rise ◽  
Reinforced Steel ◽  
Structural Plan ◽  
Nonlinear Time History

This study focuses on an analytical study on reinforced steel structures with concrete shear wall. The structures studied was analyzed using nonlinear time history method and the effect of installing  concrete shear walls in the structural plan on the target point displacement. By comparing the roofs' displacement diagrams in different structures with different layout of the shear wall in the plan, it is concluded that in order to achieve the proper result in the design of the structures, the shear walls must be located in the middle of the plan in form of core and enclosed with structural columns.  

Study on normalization of residual displacements for single-degree-of-freedom systems

2021 ◽  
pp. 875529302098801
Author(s):  
Zhibin Feng ◽  
Jinxin Gong
Keyword(s):  
Structural Characteristics ◽  
Permanent Deformation ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Intermediate Step ◽  
Residual Displacement ◽  
Inelastic Displacement ◽  
Residual Displacements ◽  
Constant Strength ◽  
Nonlinear Time History

Residual displacement spectrum is one of the most important means to predict the permanent deformation of structures after the earthquake, and various normalizations of residual displacements have generally been used for construction of the spectrum. However, the issue regarding the merits and drawbacks of each normalization has not yet been investigated thoroughly. A comparison between two normalizations that relate the residual displacements to the elastic and inelastic displacements is made in terms of the effect of ground motion and structural characteristics by means of the results of nonlinear time history analysis. The statistical results reveal that the residual-to-peak-inelastic displacement ratios have the advantages of small dispersion, samples without any outliers, and relatively symmetric distribution, which benefits from the strong correlation between residual and peak inelastic displacements. Moreover, the residual-to-peak-inelastic displacement ratios are almost independent of site conditions, significant duration, and natural periods. Consequently, the peak inelastic displacements are superior to the elastic ones as an intermediate step for residual displacements estimation, provided that the peak inelastic displacements are estimated with a low uncertainty. For providing alternatives to estimate residual displacement demands, the constant-strength residual displacement spectra are developed for both normalizations.

Seismic shear demand of ductile cantilever walls: a Canadian code perspective

1994 ◽  
Vol 21 (3) ◽  
pp. 363-376 ◽  
Author(s):  
André Filiatrault ◽  
Danilo D'Aronco ◽  
René Tinawi
Keyword(s):  
Time History ◽  
Shear Walls ◽  
Analytical Investigation ◽  
Reduction Factor ◽  
Seismic Shear ◽  
Force Reduction Factor ◽  
Force Reduction ◽  
Shear Failures ◽  
Nonlinear Time History ◽  
Shear Demand

During severe earthquakes, ductile flexural walls are expected to exhibit inelastic flexural behaviour while other brittle deformation mechanisms, such as shear, should remain elastic. The philosophy of the Canadian seismic provisions for flexural walls is based on the assumption that the force reduction factor is applicable to both flexure and shear. If the bending moments are limited because of the flexural strength of a wall, then the shear forces are considered to be limited by the same ratio. Recent case studies have not confirmed this philosophy. Brittle shear failures in walls are still possible even if their shear strengths are established by the Canadian standards. This paper presents an analytical investigation on the shear demand of ductile flexural walls designed for three different seismic zones in Canada. For each zone, an ensemble of code compatible historical earthquake ground motions is identified. The shear demand of each structure, under each earthquake record, is obtained by nonlinear time-history dynamic analyses. In 77% of the cases, the computed dynamic shear demand is higher than the current code shear strength. To address this issue, a force modification factor for shear, different from the one for flexure, is suggested for the Canadian code. Key words: earthquake, seismic response, shear walls.

scholarly journals Comparison Study of CBFs and EBFs Bracing in Steel Structures with Nonlinear Time History Analysis

2017 ◽  
Vol 3 (11) ◽  
pp. 1157
Author(s):  
Yaseer Khademi ◽  
Mehdi Rezaie
Keyword(s):  
Time History ◽  
Steel Structures ◽  
The United States ◽  
Nonlinear Time History Analysis ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
History Analysis ◽  
Concentrically Braced ◽  
History Of ◽  
Nonlinear Time History

Steel concentrically braced frames (CBFs) and Steel eccentricity braced frames (EBFs) are frequently used as efficient lateral load resisting systems to resist earthquake and wind loads. This paper focuses on high seismic applications where the brace members in CBFs and EBFs dissipate energy through repeated cycles of buckling and yielding. The present study evaluates in detail the design philosophies and provisions used in the United States for these systems. The results of a total of 176 analysis of nonlinear history of seismic behavior of CBFs and EBFs braces have been presented. Notable differences are observed between the performances of the CBFs and EBFs designed using American provisions. The similarities and differences are thoroughly discussed.

scholarly journals Proposed development of a damage-resisting Eccentrically Braced Frame with rotational active links

2011 ◽  
Vol 44 (2) ◽  
pp. 99-107 ◽  
Author(s):  
Mahbub H. Khan ◽  
G. Charles Clifton
Keyword(s):  
Time History ◽  
Damage Threshold ◽  
Integration Time ◽  
Maximum Displacement ◽  
Braced Frame ◽  
Axial Extension ◽  
Average Maximum ◽  
Strength And Stiffness ◽  
Ductility Capacity ◽  
Active Link

Eccentrically Braced Frames (EBFs) are widely used seismic-resisting systems, as they allow both strength and stiffness to be optimised while providing good ductility capacity. However, in theory they have a low damage threshold in severe earthquakes and post-earthquake repair of conventional EBFs will be difficult and expensive. This paper presents the Numerical Integration Time-History (NITH) analysis of two ten storey EBF buildings; one with a conventional active link and the other with a new form of low damage active link based on rotational sliding bolted plates. The low damage active link can be designed to allow rotation only, or to allow both rotation and axial extension. The conventional active link response in terms of displacement, rotation and inelastic demand was well within the range of the rotational active links under the records considered. The analysis shows that average maximum displacement of the building and rotation of the link for both the rotational and the rotational+extension active links was almost identical. The extension of the rotational active link permitting axial extension was less than 1.5 mm. Axial load demands on the collector beams and braces were similar in the case all three active links. It can be concluded from the analysis that the rotational active link with extension is not required, as the lateral extensions can be accommodated within the rotational plates with nominal clearances in the bolt holes to accommodate the lateral extension.

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