Evaluation of Seismic Performance of Improved Rocking Concentrically Braced-frames with Zipper Columns

Restoring Force ◽

Braced Frame ◽

Concentrically Braced ◽

Rocking Behavior ◽

Post Tensioned

Concentrically braced frames (CBFs) as one of well-known stiff and common lateral force resisting systems often show limited ductility capacity under severe earthquakes. This study proposes rocking zipper braced frame (RZBF) to improve the drift capacity of CBFs which is based on combination of rocking behavior and zipper columns. In the RZBF system, rocking behavior permit the braced frame to uplift during the earthquake and then restoring force induced through post-tensioned bars self-center the frame to its initial state. Also, zipper columns can decrease the concentration of damage by distributing the unbalance force at the mid bay over the frame’s height. To assess the performance of RZBF, a comparison study is carried out considering CBF, rocking concentrically braced frame, zipper braced frame and RZBF. For this purpose, some frames structures are designed and nonlinear time history analysis conduct under a set of earthquake records. Seismic responses such as roof drift ratio, gap opening at the column-base interface, forces of top story braces and post-tensioned bars are taken into consideration. The results show that the proposed RZBF has better performance among the others and zipper columns can improve the behavior of rocking systems.

Seismic evaluation of single-storey steel buildings

10.1139/l99-002 ◽

1999 ◽

Vol 26 (4) ◽

pp. 379-394 ◽

Cited By ~ 4

Author(s):

M S Medhekar ◽

DJL Kennedy

Keyword(s):

Seismic Performance ◽

Response Spectrum ◽

Time History ◽

Analytical Models ◽

Steel Buildings ◽

Braced Frame ◽

Seismic Zones ◽

The seismic performance of single-storey steel buildings, with concentrically braced frames and a roof diaphragm that acts structurally, is evaluated. The buildings are designed in accordance with the National Building Code of Canada 1995 and CSA Standard S16.1-94 for five seismic zones in western Canada with seismicities ranging from low to high. Only frames designed with a force modification factor of 1.5 are considered. Analytical models of the building are developed, which consider the nonlinear seismic behaviour of the concentrically braced frame, the strength and stiffness contributions of the cladding, and the flexibility, strength, and distributed mass of the roof diaphragm. The seismic response of the models is assessed by means of a linear static analysis, a response spectrum analysis, a nonlinear static or "pushover" analysis, and nonlinear dynamic time history analyses. The results indicate that current design procedures provide a reasonable estimate of the drift and brace ductility demand, but do not ensure that yielding is restricted to the braces. Moreover, in moderate and high seismic zones, the roof diaphragm responds inelastically and brace connections are overloaded. Recommendations are made to improve the seismic performance of such buildings.Key words: analyses, concentrically braced frame, dynamic, earthquake, flexible diaphragm, low-rise, nonlinear, seismic design, steel.

The Effect of Local Fuse on Behavior of Concentrically Braced Frame by a Numerical Study

Civil Engineering Journal ◽

10.28991/cej-0309123 ◽

2018 ◽

Vol 4 (3) ◽

pp. 655 ◽

Cited By ~ 2

Author(s):

Ali Kachooee ◽

Mohammad Ali Kafi ◽

Mohsen Gerami

Keyword(s):

Seismic Response ◽

Numerical Study ◽

Numerical Models ◽

Compressive Loading ◽

Braced Frames ◽

Reduced Cross Section ◽

Braced Frame ◽

The concentrically braced frames (CBFs) are one of the most widely used lateral load-resisting systems. Seismic performance of these structures has a weakness that is due to the brace buckling at a lower loading than the ultimate compressive loading capacity. In this paper, attempt is made to enhance the seismic response of CBFs through utilizing a local fuse. For this purpose, first the formulation of fuse area and length are presented. Then based on this formulation, several numerical models have been built and analyzed to examine the effect of implementing this fuse on seismic response of CBFs. From the analyses results, it is found that if the reduced cross-section fuse (RCF) is properly designed and also the end of brace is fixed, the CBFs with equal energy dissipation capacity, that are equipped with this fuse exhibit a better ductility than the customary CBFs.

Seismic response of two-storey buildings with concentrically braced steel frames

10.1139/l99-007 ◽

1999 ◽

Vol 26 (4) ◽

pp. 497-509 ◽

Cited By ~ 2

Author(s):

M S Medhekar ◽

DJL Kennedy

Keyword(s):

Seismic Response ◽

Response Spectrum ◽

Time History ◽

Steel Buildings ◽

Capacity Design ◽

Braced Frame ◽

Seismic Zones ◽

The seismic performance of two-storey steel buildings with concentrically braced frames as the lateral load resisting system is evaluated. The buildings are designed in accordance with the National Building Code of Canada (1995) and CSA Standard S16.1-94 for five seismic zones in western Canada. Only frames designed with a force modification factor of 1.5 are considered. Analytical models of the buildings are developed, which consider the nonlinear seismic behaviour of the concentrically braced frame, the shear strength of the roof diaphragm, and the stiffness and strength contributions of the nonstructural partitions. The seismic response is estimated with nonlinear static and dynamic time history analyses. Roof diaphragm flexibility does not influence the dynamic behaviour significantly. The distribution of lateral forces from response spectrum analysis agrees well with that specified. Current design procedures provide reasonable estimates of the lateral drift in low and moderate seismic zones. Brace ductility demands are reasonable and may be limited due to the contributions of nonstructural partitions. However, in moderate and high seismic zones, the connections, beams, columns, and roof diaphragm are overloaded. The capacity design procedure is recommended to provide adequate resistance to the overloaded components.Key words: analyses, capacity design, concentrically braced frame, diaphragm, dynamic, earthquake, low-rise, nonlinear, seismic design, steel.

Validation of nonlinear time history analysis models for single-storey concentrically braced frames using full-scale shake table tests

Earthquake Engineering & Structural Dynamics ◽

10.1002/eqe.2264 ◽

2012 ◽

Vol 42 (8) ◽

pp. 1151-1170 ◽

Cited By ~ 18

Author(s):

J. Goggins ◽

S. Salawdeh

Keyword(s):

Time History ◽

Nonlinear Time History Analysis ◽

Shake Table ◽

Braced Frames ◽

Shake Table Tests ◽

History Analysis ◽

Concentrically Braced ◽

Nonlinear Time History ◽

Analysis Models

Rehabilitation of steel concentrically braced frames with rocking cores for improved performance under near-fault ground motions

Advances in Structural Engineering ◽

10.1177/1369433216668101 ◽

2016 ◽

Vol 20 (6) ◽

pp. 940-952 ◽

Cited By ~ 11

Author(s):

Bing Qu ◽

Francisco Sanchez-Zamora ◽

Michael Pollino ◽

Hetao Hou

Keyword(s):

Ground Motions ◽

Braced Frames ◽

Braced Frame ◽

Near Fault ◽

Modal Properties ◽

Core Technology ◽

Concentrically Braced ◽

Near Fault Earthquakes

This article focuses on evaluating the adequacy of a seismic rehabilitation technology which adds rocking cores to deficient steel concentrically braced frames in near-fault regions. Two demonstration buildings were rehabilitated with the technology. Seismic performance of the rehabilitated buildings was evaluated through numerical simulations. Analysis results suggest that the code-compliant concentrically braced frames may be vulnerable to collapse under the fault-normal components of the near-fault ground motions, approximately having a probability of exceedance of 10% in 50 years. It is found that the Rocking Core technology is effective in reducing the inter-story drift responses of the demonstration buildings under near-fault earthquakes. The rehabilitated systems can further benefit from the use of hysteretic energy dissipating links between the rocking cores and existing concentrically braced frames. This article also addresses the influence of the rocking cores on modal properties of the rehabilitated buildings. It is found that the rocking core with moderate stiffness does not significantly alter the modal properties of a rehabilitated concentrically braced frame.

Cyclic Behaviors of Steel Braces in Concentrically Braced Frames

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.847.128 ◽

2016 ◽

Vol 847 ◽

pp. 128-134

Author(s):

Zhi Hao Zhou ◽

Camillo Nuti ◽

Davide Lavorato ◽

Alessandro Vittorio Bergami

Keyword(s):

Experimental Data ◽

Plastic Hinge ◽

Material Model ◽

Braced Frames ◽

Braced Frame ◽

New Model ◽

Concentrically Braced ◽

Different Types

In this paper, a new model named as “brace01” for steel brace is presented on the basis of experimental data on different types of steel struts. This model shows a peasant capability in the structural analysis of Concentrically Braced Frames. A brace is idealized as a pin-ended member with a plastic hinge located at its midspan. This expression of the model is proposed by combining the mechanical properties and the phenomenological characters. The model for steel brace is implemented in an effective way in OpenSees. The calibration of the material model is done by comparing the numerical curves generated by the numerical model with the experimental curves of pin-ended steel braces. The new model is proved applicable to practical Concentrically Braced Frame.

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

Civil Engineering Journal ◽

10.28991/cej-030945 ◽

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 ◽

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.

Floor Spectra Estimates for an Industrial Special Concentrically Braced Frame Structure

Journal of Pressure Vessel Technology ◽

10.1115/1.4041285 ◽

2018 ◽

Vol 141 (1) ◽

Author(s):

Roberto Javier Merino Vela ◽

Emanuele Brunesi ◽

Roberto Nascimbene

Keyword(s):

Time History ◽

Response Spectra ◽

Frame Structure ◽

Eurocode 8 ◽

Industrial Complex ◽

Braced Frame ◽

Nonstructural Components ◽

Floor Response Spectra ◽

Nonstructural components play an important role in the correct functioning of industrial facilities, which may suffer greatly from earthquake-induced actions, as demonstrated by past seismic events. Therefore, the correct evaluation of seismic demands acting upon them is of utmost importance when assessing or designing an industrial complex exposed to seismic hazard. Among others, nonlinear time history analyses (NLTHA) of structural systems including nonstructural elements and floor response spectra are well-known methods for computing these actions, the former being more accurate and the latter being less onerous. This work focuses on deriving floor spectra for a steel special concentrically braced frame (SCBF), which is a common type of lateral-load resisting system for industrial frames. The results are used to compute the seismic actions on a small liquid storage tank mounted on the case study frame. Additionally, the results are compared to those obtained by modeling the structure and the tank together, that is, by modeling the tank explicitly and incorporating it within the model of the support structure. To this end, a simple model, consisting of two uncoupled single degree-of-freedom systems, is used for the tank. The floor spectra resulting from both approaches are compared to establish differences in the behavior of the structure and nonstructural element/component. Finally, the seismic demand on the tank—obtained by direct and indirect analyses—is compared to that obtained by applying ASCE 7-10 and Eurocode 8 prescriptions.

Earthquake resistant design of concentrically braced steel frames

10.1139/l91-101 ◽

1991 ◽

Vol 18 (5) ◽

pp. 839-850 ◽

Cited By ~ 28

Author(s):

R. G. Redwood ◽

V. S. Channagiri

Keyword(s):

Structural Engineering ◽

Steel Structures ◽

Braced Frames ◽

Braced Frame ◽

Earthquake Resistant Design ◽

Earthquake Resistant ◽

Concentrically Braced ◽

Engineering Steel ◽

The Impact

New provisions of the CSA standard for steel structures (CAN/CSA-S16.1-M89) dealing with detailing of concentrically braced frames for seismic design are described and related to requirements of the National Building Code of Canada. The basis of the new requirements is outlined, and an example eight-storey frame is used to outline a methodology for the design process for a ductile braced frame and to illustrate the impact of the provisions. Key words: design, structural engineering, steel, earthquakes, braced frame, standards.

Code provisions for seismic design for concentrically braced steel frames

10.1139/l92-122 ◽

1992 ◽

Vol 19 (6) ◽

pp. 1025-1031 ◽

Cited By ~ 4

Author(s):

R. G. Redwood ◽

A. K. Jain

Keyword(s):

Seismic Design ◽

Structural Engineering ◽

Steel Frames ◽

Braced Frames ◽

Braced Frame ◽

Concentrically Braced ◽

Interstorey Drift ◽

Available Information ◽

Steel Braced Frame

Extensive research into the inelastic seismic response of concentrically braced frames and their components has been carried out in the last two decades. This knowledge has now been incorporated into seismic design practice in several countries, notably the U.S.A., Canada, and New Zealand. In this paper, design specifications from these three countries, which derive largely from the same body of research, are compared. The basic design philosophy for concentrically braced steel frames, loading, and member detailing are examined. It is concluded that, in general, the Canadian specifications are in conformity with the available information and have many similar features to codes of the other countries. Significant differences exist in the classification of braced frames, between interstorey drift requirements, in the treatment of dual structural systems, and to a lesser extent in member detailing requirements. Some features of Canadian codes meriting review are identified. Key words: structural engineering, earthquakes, standards, steel, braced frame, ductility, concentric bracing, dual system.