Development of a Hybrid Simulation Computational Model for Steel Braced Frames

2018 ◽  
Vol 763 ◽  
pp. 609-618
Author(s):  
Ali Imanpour ◽  
Robert Tremblay ◽  
Martin Leclerc ◽  
Romain Siguier
Keyword(s):  
Computational Model ◽  
Hybrid Simulation ◽  
Structural Testing ◽  
Frame Structure ◽  
Axial Stiffness ◽  
Braced Frames ◽  
Element Analysis ◽  
Braced Frame ◽  
Concentrically Braced Frame ◽  
Dynamic Hybrid

Hybrid simulation is an economical structural testing technique in which the critical part of the structure expected to respond in the inelastic range is tested physically whereas the rest of the structure is modelled numerically using a finite element analysis program. The article describes the development of a computational model for the hybrid simulation of the seismic collapse of a steel two-tiered braced frame structure due to column buckling. The column stability response in multi-tiered braced frames is first presented using a pure numerical model of the braced frame studied. The development of the hybrid simulation computational model is then discussed. Effects of initial out-of-straightness imperfections and axial stiffness, P-Delta analysis approach, and gravity analysis technique on the hybrid simulation results are evaluated using a numerical hybrid simulation model. Finally, the results of a continuous pseudo-dynamic hybrid simulation of the seismic response of the steel multi-tiered concentrically braced frame are presented. The test showed that failure of columns by instability is a possibility and can lead to collapse of multi-tiered braced frames, as was predicted by numerical analysis. Furthermore, suitable modeling methods are proposed for hybrid simulation of steel braced frame structures.

Experimental and numerical studies on Seismic Performance of The SCFST Column Eccentrically Braced Frames

2020 ◽  
pp. 136943322095060
Author(s):  
Ya-Peng Wu ◽  
Zhi-Hua Chen ◽  
Ting Zhou ◽  
Xian-Dong Chen ◽  
Xiao-Dun Wang
Keyword(s):  
Finite Element ◽  
Energy Dissipation ◽  
Damage Mechanism ◽  
Steel Tube ◽  
Braced Frames ◽  
Static Properties ◽  
Element Analysis ◽  
Eccentrically Braced Frames ◽  
Braced Frame ◽  
Concentrically Braced Frame

The quasi-static experiments and finite element analysis of three groups of special-shaped concrete-filled steel tube (SCFST) column chevron braced frames (two groups of eccentrically braced frames and one group of concentrically braced frame) were carried out. The differences of quasi-static mechanical properties between the three groups frame were compared. The damage mechanism of the concentrically and eccentrically braced frames was significantly different, and the eccentrically braced frame could significantly improve the energy-dissipation ability and ductility. When the single limb of columns was connected by double-steel-plate, the stiffness of eccentrically braced structure could be improved around 10.4% and showed better energy-dissipation capacity. The finite element simulation was built on the basis of experiments, and parametric analysis was examined. The analysis results showed that section forms of the SCFST column and the thickness of brace have significant impacts on the quasi-static properties of such type of structure.

Floor Spectra Estimates for an Industrial Special Concentrically Braced Frame Structure

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 ◽  
Concentrically Braced Frame ◽  
Concentrically Braced

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.

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

2018 ◽  
Vol 4 (3) ◽  
pp. 655 ◽  
Author(s):  
Ali Kachooee ◽  
Mohammad Ali Kafi ◽  
Mohsen Gerami
Keyword(s):  
Seismic Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Compressive Loading ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Reduced Cross Section ◽  
Braced Frame ◽  
Concentrically Braced Frame ◽  
Concentrically Braced

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.

scholarly journals Full-Scale Blast Tests on a Conventionally Designed Three-Story Steel Braced Frame with Composite Floor Slabs

Vibration ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 865-892
Author(s):  
Michalis Hadjioannou ◽  
Aldo E. McKay ◽  
Phillip C. Benshoof
Keyword(s):  
Full Scale ◽  
Frame Structure ◽  
Blast Loads ◽  
Braced Frames ◽  
Test Program ◽  
Braced Frame ◽  
Earthquake Loads ◽  
Floor Slabs ◽  
Minimal Damage ◽  
Steel Braced Frame

This paper summarizes the findings of two full-scale blasts tests on a steel braced frame structure with composite floor slabs, which are representative of a typical office building. The aim of this research study was to experimentally characterize the behavior of conventionally designed steel braced frames to blast loads when enclosed with conventional and blast-resistant façade. The two tests involved a three-story, steel braced frame with concentrical steel braces, which are designed to resist typical gravity and wind loads without design provisions for blast or earthquake loads. During the first blast test, the structure was enclosed with a typical, non-blast-resistant, curtainwall façade, and the steel frame sustained minimal damage. For the second blast test, the structure was enclosed with a blast-resistant façade, which resulted in higher damage levels with some brace connections rupturing, but the building did not collapse. Observations from the test program indicate the appreciable reserved capacity of steel brace frame structures to resist blast loads.

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

2016 ◽  
Vol 20 (6) ◽  
pp. 940-952 ◽  
Author(s):  
Bing Qu ◽  
Francisco Sanchez-Zamora ◽  
Michael Pollino ◽  
Hetao Hou
Keyword(s):  
Ground Motions ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Braced Frame ◽  
Near Fault ◽  
Modal Properties ◽  
Concentrically Braced Frame ◽  
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

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 ◽  
Concentrically Braced Frames ◽  
Braced Frame ◽  
New Model ◽  
Concentrically Braced Frame ◽  
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.

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

2020 ◽  
Author(s):  
Nasim Irani Sarand ◽  
Abdolrahim Jalali
Keyword(s):  
Time History ◽  
Nonlinear Time History Analysis ◽  
Braced Frames ◽  
Concentrically Braced Frames ◽  
Restoring Force ◽  
Braced Frame ◽  
Concentrically 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.

Frame and Brace Action Forces on Steel Corner Gusset Plate Connections in Buckling-Restrained Braced Frames

2012 ◽  
Vol 28 (2) ◽  
pp. 531-551 ◽  
Author(s):  
Chung-Che Chou ◽  
Jia-Hau Liu
Keyword(s):  
Axial Strain ◽  
Free Edge ◽  
Braced Frames ◽  
Element Analysis ◽  
Gusset Plate ◽  
Braced Frame ◽  
Test Frame ◽  
Force Components ◽  
Buckling Restrained Braced Frames ◽  
Plate Connections

This work presents test and finite element analysis results for a steel buckling-restrained braced frame (BRBF). The objectives are to evaluate the forces of frame and brace actions on the corner gusset plate and to develop a method that considers both actions in design. The BRBF test frame exhibited excellent performance up to a drift of 2% with a maximum axial strain of 1.7% in the buckling-restrained brace. Without free-edge stiffeners, the corner gusset plate buckled at a significantly lower strength than that predicted by the American Institute of Steel Construction (AISC) specifications ( AISC 2005a ). By idealizing the corner gusset plate as a strut, a strut model can be used to determine the forces resulting from frame action, which are on the same order as the brace forces. Considering the stress distributions and force components from the frame and brace actions, the maximum stresses in the gusset tips are used as an additional design parameter for sizing gusset connections.

Investigation of hybrid multi-core buckling-restrained brace components

2021 ◽  
Author(s):  
Pierre Thibault ◽  
Charles-Darwin Annan ◽  
Pampa Dey
Keyword(s):  
Seismic Energy ◽  
Carbon Steels ◽  
Axial Deformation ◽  
Braced Frames ◽  
Braced Frame ◽  
Concentrically Braced Frame ◽  
Multiple Cores ◽  
Yield Behaviour ◽  
Promising Solution ◽  
Brb System

<p>Contemporary seismic-resistant design of steel braced frames is based on dissipating seismic energy through significant inelastic axial deformation in brace components. Buckling-restrained braced (BRB) frames are a type of concentrically braced frame (CBF) characterised by braces that yield both in tension and in compression. These braces therefore exhibit superior cyclic performance compared with traditional CBFs. However, buckling-restrained braces commonly display a low post- yield stiffness, causing substantial interstory drifts and large residual drifts after seismic events. Moreover, yielding of the core is often only tied to a single performance objective, thus making its performance at other levels of seismicity largely unknown. One promising solution is the use of a hybrid BRB, where multiple cores made from different metals are connected in parallel to work together and complement each other. This research is geared towards first evaluating the potential of different combinations of core materials, followed by the design of a hybrid BRB system that can accommodate multiple core plates. Results show that the post-yield behaviour of hybrid BRBs is improved by employing a combination of 350WT carbon steel and another metal with low-yield and high strain-hardening behaviour, such as stainless steels, aluminium alloys, or other grades of carbon steels. Finally, a detailed overview of one hybrid BRB solution is proposed.</p>

Seismic evaluation of single-storey steel buildings

1999 ◽  
Vol 26 (4) ◽  
pp. 379-394 ◽  
Author(s):  
M S Medhekar ◽  
DJL Kennedy
Keyword(s):  
Seismic Performance ◽  
Response Spectrum ◽  
Time History ◽  
Analytical Models ◽  
Steel Buildings ◽  
Concentrically Braced Frames ◽  
Braced Frame ◽  
Seismic Zones ◽  
Concentrically Braced Frame ◽  
Concentrically Braced

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.

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