Effect of Column Base Flexibility on Earthquake-Induced Residual Deformations of Steel Columns

2018 ◽  
Vol 763 ◽  
pp. 149-156 ◽  
Author(s):  
Hiroyuki Inamasu ◽  
Dimitrios G. Lignos ◽  
Amit M. Kanvinde
Keyword(s):  
Finite Element ◽  
Local Buckling ◽  
Steel Columns ◽  
Steel Moment Resisting Frames ◽  
High Rise ◽  
Moment Resisting ◽  
Residual Deformations ◽  
Steel Mrfs ◽  
Column Base ◽  
Axial Shortening

Post-earthquake residual deformations often control decisions regarding potential demolition of earthquake-damaged buildings. While residual deformations are typically assumed to be lateral, the column residual axial shortening has similar implications for such decisions. This paper investigates the effect of column base flexibility on residual axial shortening of columns in steel moment resisting frames (MRFs). The mechanistic reason for this dependency is that higher base flexibility reduces plastic rotation demands in the column, in turn mitigating local buckling-induced shortening. To investigate this issue, parametric finite element (FE) simulations interrogate various column sizes used in conventional mid-to high-rise steel MRFs. The simulations suggest at 1-2% story drifts, the base flexibility virtually eliminates the column axial shortening.

Effect of Column Base Behavior on Seismic Performance of Multi-Story Steel Moment Resisting Frames

2018 ◽  
Vol 19 (01) ◽  
pp. 1940007 ◽  
Author(s):  
Yao Cui ◽  
Fengzhi Wang ◽  
Satoshi Yamada
Keyword(s):  
Plastic Deformation ◽  
Local Buckling ◽  
Time History ◽  
Thickness Ratio ◽  
Nonlinear Time History Analysis ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
The Moment ◽  
Column Base

Column base is one of the most important elements of steel structures. Exposed column base is commonly used in low-to-medium-rise steel moment resisting frames because of better constructability and low cost. To study the effect of exposed column base behavior on the seismic behavior of low-to-medium-rise steel moment resisting frames, a four-story, four-bay steel moment frame is studied by the nonlinear time history analysis. In the numerical analysis, two types of column base connections (rigid and semi-rigid) are considered. The width–thickness ratio of column and stiffness ratio of column base to column are chosen as the analysis parameters. The characteristics of structural responses, hysteresis loops, and the distribution of plastic energy dissipation are compared. It indicates that the collapse margin ratio is significantly increased when the exposed column base behavior is considered for the moment resisting frames with large width–thickness ratio. Moreover, if the column base connection is allowed to rotate and transfer a portion of the moment, the demand of plastic deformation capacity of steel columns is reduced, then subsequently strength deterioration caused by the local buckling at the bottom of column could be avoided. Also, the whole structure has a better ductility, the ability of plastic deformation and energy absorbance of the moment resisting frame under earthquake are therefore enhanced. The structure with the semi-rigid column base connection has larger potential to avoid the structural collapse caused by the local buckling of first-story columns.

Performance-based assessment of seismic-resilient steel moment resisting frames equipped with innovative column base connections

Structures ◽  
2021 ◽  
Vol 32 ◽  
pp. 1646-1664
Author(s):  
Elena Elettore ◽  
Annarosa Lettieri ◽  
Fabio Freddi ◽  
Massimo Latour ◽  
Gianvittorio Rizzano
Keyword(s):  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Performance Based Assessment ◽  
Moment Resisting ◽  
Base Connections ◽  
Column Base

Performance‐based assessment of seismic‐resilient steel moment resisting frames equipped with innovative column base connections

ce/papers ◽  
2021 ◽  
Vol 4 (2-4) ◽  
pp. 1736-1746
Author(s):  
Annarosa Lettieri ◽  
Elena Elettore ◽  
Fabio Freddi ◽  
Massimo Latour ◽  
Gianvittorio Rizzano
Keyword(s):  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Performance Based Assessment ◽  
Moment Resisting ◽  
Base Connections ◽  
Column Base

Seismic fragility of steel moment-resisting frames in Vancouver and Montreal designed in the 1960s, 1980s, and 2010

2015 ◽  
Vol 42 (11) ◽  
pp. 919-929 ◽  
Author(s):  
Lucía Valentina Díaz Gómez ◽  
Oh-Sung Kwon ◽  
Mohammad Reza Dabirvaziri
Keyword(s):  
Numerical Models ◽  
Fragility Curves ◽  
Time History ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Nonlinear Time History Analyses ◽  
Moment Resisting ◽  
The 1960S ◽  
Steel Mrfs ◽  
Nonlinear Time History

Typical steel moment-resisting frames (MRF) of six-storey buildings in Vancouver and Montreal were designed for three different provisions of the National Building Code of Canada (1960s, 1980s, and 2010). Numerical models were developed in OpenSees to understand the seismic performance of the structures. These models accounted for strength and stiffness degradation through appropriate representations of the beam–column connection behaviours, which were calibrated against experimental results available in the literature. The behaviour of the buildings was evaluated through pushover and nonlinear time history analyses. The pushover analysis results showed that the 1960s and 2010 steel MRFs of both cities exhibited strong-column-weak-beam failure mode. The 1980s steel MRFs of both cities showed soft-storey mechanism. Fragility curves were developed for the steel MRFs based on the seismic demands evaluated using nonlinear time history analyses, which can be used for regional seismic impact assessment studies in the future.

From Design to Earthquake Loss Assessment of Steel Moment-Resisting Frames

2018 ◽  
Vol 763 ◽  
pp. 124-130 ◽  
Author(s):  
Luís Macedo ◽  
Antonio Silva ◽  
José Miguel Castro
Keyword(s):  
Seismic Design ◽  
Eurocode 8 ◽  
Loss Assessment ◽  
Behaviour Factor ◽  
Steel Moment Resisting Frames ◽  
Performance Factors ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Earthquake Loss ◽  
Steel Mrfs

Steel moment-resisting frames (MRFs) are well known for their ductile and stable hysteretic behaviour. For this reason, they are an attractive and effective structural system for seismic resistance. Current seismic design codes, namely Eurocode 8, provide system performance factors that should be used in the seismic design under different ductility classes. However, recent research studies have shown that the use of the code-prescribed performance factors lead to stiffer and heavier structural solutions that are not consistent with the performance-based design assumptions. A new methodology, Improved Force-Based Design (IFBD), has recently been proposed with the aim of a more rational determination of the adopted value of the behaviour factor, q, instead of using the upper bound reference values provided by the design code. This paper investigates if the obtained values of q for both EC8 and IFBD concerning steel MRFs are not only adequate, but also provide sufficient margins against collapse under maximum considered earthquake (MCE) ground motions. To this end, the methodology proposed in FEMA P695 was used. Additionally, the expected direct economic seismic losses are computed according to the PEER-PBEE methodology.

Effect of Column-Base Flexibility on the Seismic Response and Safety of Steel Moment-Resisting Frames

2013 ◽  
Vol 29 (4) ◽  
pp. 1537-1559 ◽  
Author(s):  
Farzin Zareian ◽  
Amit Kanvinde
Keyword(s):  
Nonlinear Response ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Steel Moment Resisting Frames ◽  
Four Frames ◽  
Plastic Mechanism ◽  
Fixed Base ◽  
Moment Resisting ◽  
Ductility Capacity ◽  
Column Base

The effect of column-base flexibility on the response of steel moment frames is assessed through parametric simulation. The response of four frames (2-, 4-, 8-, and 12-story), designed as per current codes, is investigated through static push-over simulations and sophisticated nonlinear response-history simulations, including collapse simulation. For each frame, a range of base fixities is interrogated, including realistic values that are calculated from the designed connections. The results indicate that a reduction in base fixity alters the force distribution and the plastic mechanism, significantly reducing ductility capacity and strength, as well as collapse resilience, while increasing member forces. For the 4-, 8-, and 12-story frames, this trend suggests that the expected response of such frames is worse than is implied by simulations and design approaches that assume a fixed-base condition. However, the trend is beneficial for the 2-story frame, which is analyzed and designed assuming a pinned base.

Preliminary Finite Element Analyses on Seismic Resistant FREE from DAMage Beam to Column Joints under Impact Loading

2018 ◽  
Vol 763 ◽  
pp. 592-599 ◽  
Author(s):  
Marina D'Antimo ◽  
Mariana Zimbru ◽  
Mario D'Aniello ◽  
Jean François Demonceau ◽  
Jean Pierre Jaspart ◽  
...  
Keyword(s):  
Finite Element ◽  
Impact Loading ◽  
Rational Design ◽  
Design Guidelines ◽  
Dissipative Systems ◽  
Finite Element Analyses ◽  
Steel Moment Resisting Frames ◽  
Structural Robustness ◽  
Moment Resisting ◽  
Push Down

Nowadays, the interest on structural robustness is increasing because of the recent terroristic attacks. Although a large number of research projects have been carried out in this field, limited design guidelines as well as code recommendations are nowadays available. Leading to the fact that the design for robustness is far from being current practice. Conversely, the design for natural hazards as the earthquake is a well-consolidated practice and modern codes implement effective and well-recognized design rules. Even though seismic design philosophy based on the concept of hierarchy of resistance enables structural robustness for conventional structural systems, this is not demonstrated for structures equipped with anti-seismic devices as well as innovative dissipative systems. Recently, the use of friction based dissipative joints has been proved to be a promising solution for seismically design steel moment resisting frames. However, the robustness and the resistance against impact loading of this type of joints is not yet investigated. With the aim to develop an experimental campaign based on impact tests, preliminary finite element analyses have been carried out to identify the main criticisms and to drive the rational design of the joint specimens. With this regard, in the present paper, the results of a numerical parametric study on the preliminary push-down test are presented and discussed.

scholarly journals Pushover Response of Multi Degree of Freedom Steel Frames

2020 ◽  
Vol 6 ◽  
pp. 86-97
Author(s):  
Tayyab Naqash
Keyword(s):  
Parametric Analysis ◽  
Behaviour Factor ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Overall Performance ◽  
Complex Structural ◽  
Drift Limit ◽  
Steel Mrfs ◽  
High Deformability

Seismic codes use the behaviour factor to consider the ductility and the structure's non-linearity to improve the system's overall performance. Generally, Steel moment-resisting frames are characterized by a relatively high period showing high deformability and, foreseen that with stringent damageability criteria, the adopted behaviour factor might not optimally be utilized for achieving better performance of the frames. The design is generally governed by stiffness, leaving behind a complex structural system where the capacity design rules are disturbed and therefore necessitates to relax the drift limits for such frames. Given this and with extensive parametric analysis, the current paper aims to examine the behaviour factor of steel Moment Resisting Frames (MRFs). The parametric analysis has been conducted on rigid steel MRFs of 9, 7, and 5 storeys with bay 4 different bay widths of 9.15 m, 7.63 m, 6.54 m, and 5.08 m. Perimeter frame configuration has been designed using 4 different behaviour factors (q = 6.5, 4, 3, and 2) for a total number of 144 cases. Static nonlinear analysis has been conducted, and consequently, the behaviour factors have been examined. It has been observed that compatibility is required while choosing the drift limit for an assumed ductility class of the code. Doi: 10.28991/cej-2020-SP(EMCE)-08 Full Text: PDF

scholarly journals EXPERIMENTAL RESPONSE OF A LOW-YIELDING, SELF CENTERING, ROCKING COLUMN BASE JOINT WITH FRICTION DAMPERS

2021 ◽  
Author(s):  
Massimo Latour ◽  
Gianvittorio Rizzano
Keyword(s):  
Energy Dissipation ◽  
The Self ◽  
Friction Dampers ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting ◽  
Restoring Forces ◽  
Energy Dissipation System ◽  
Unloading Stiffness ◽  
Column Bases ◽  
Column Base

The sliding hinge joint (SHJ) is a supplemental energy dissipation system for column bases or beam-to-column connections of steel Moment Resisting Frames (MRFs). It is based on the application of symmetric/asymmetric friction dampers to develop a dissipative mechanism alternative to the column/beam yielding. This typology was initially proposed in New Zealand and, more recently, is starting to be tested and applied also in Europe. While on the one hand this technology provides great benefits such as the damage avoidance, on the other hand, due to the high unloading stiffness of the dampers in tension or compression, its cyclic response is typically characterized by a limited self-centering capacity.To address this shortcoming, the objective of the work herein presented is to examine the possibility to add to these connections also a self-centering capacity proposing new layouts based on a combination of friction devices (providing energy dissipation capacity), pre-loaded threaded bars and disk springs (introducing in the joint restoring forces).In this paper, as a part of an ongoing wider experimental activity regarding the behavior of self-centering connections, the attention is focused on the problem of achieving the self-centering of the column bases of MRFs by studying a detail consisting in a column-splice equipped with friction dampers and threaded bars with Belleville disk springs, located above a traditional full-strength column base joint. The main benefits obtained with the proposed layout are that: (i) the self-centering capability is obtained with elements (threaded bars and Belleville springs) which have a size comparable to the overall size of the column-splice cover plates; (ii) all the re-centering elements are moved far from the concrete foundation avoiding any interaction with the footing. The work reports the main results of an experimental investigation and the analysis of a MRF equipped with the proposed column base joints.

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