Seismic performance of concentrically braced frame with hexagonal pattern of braces to mitigate soft story behavior

2018 ◽  
Vol 175 ◽  
pp. 27-40 ◽  
Author(s):  
Niloufar Mashhadiali ◽  
Ali Kheyroddin
Keyword(s):  
Seismic Performance ◽  
Braced Frame ◽  
Soft Story ◽  
Hexagonal Pattern ◽  
Concentrically Braced Frame ◽  
Concentrically Braced

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.

scholarly journals Seismic Performance Analysis of Self-Centering Concentrically Braced Steel Frame Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Ergang Xiong ◽  
Kun Zu ◽  
Qian Zhang
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Repeated Loading ◽  
Base Shear ◽  
Cross Sectional ◽  
Braced Frame ◽  
Residual Drift ◽  
Concentrically Braced Frame ◽  
History Analysis ◽  
Concentrically Braced

To study the seismic performance of self-centering concentrically braced frame (SC-CBF) structure, the static elastoplastic analysis, low-cycle repeated loading analysis, and elastoplastic time-history analysis were conducted for a four-story SC-CBF structure, compared with the traditionally concentrically braced frame (CBF) structure. The influences of different GAP stiffnesses and cross-sectional areas of prestressed tendon were investigated on the self-centering and seismic performance of the SC-CBF structure. The results show that the SC-CBF structure has a strong lateral resistance, a small base shear under earthquake action, and a slight residual drift after unloading. The SC-CBF structure has a better ductility than the CBF structure. The displacement of the SC-CBF structure under the action of rare and extremely rare earthquakes is large, and the structure can dissipate more energy; the interstory drift is large, but the residual drift is small, exhibiting its ideal seismic and self-centering performance. However, the mechanical behavior of prestressed tendons is significantly affected by the stiffness of the GAP. The mechanical and seismic performances of the overall structure are slightly affected by the stiffness of the GAP, but the cross-sectional area of the prestressed tendons has a remarkable influence on the overall performance of the structure.

Drift Concentration of a Three-Story Special Concentrically Braced Frame with Strongback under Earthquake Loading

2017 ◽  
Vol 863 ◽  
pp. 287-292 ◽  
Author(s):  
Chui Hsin Chen ◽  
I Jung Tsai ◽  
Yao Tang
Keyword(s):  
Case Studies ◽  
Permanent Deformation ◽  
Local Deformation ◽  
Braced Frame ◽  
Soft Story ◽  
Concentrically Braced Frame ◽  
Drift Ratio ◽  
Concentrically Braced ◽  
Structural Demand ◽  
Strength And Stiffness

In conventional special concentrically braced frame (SCBF) structures, the buckling of the braces leads to severe reduction in system strength and stiffness. Therefore soft story mechanisms followed by large permanent deformation are commonly observed in SCBF structures. The strongback system using additional structural components along the height of the building to resist local deformation is able to improve the distribution of the drift. This research conducted case studies to investigate the effects of strength and stiffness of the strongback system on the behavior of typical three-story SCBF system. The primary variables to be investigated are stiffness factor α (strongback stiffness/SCBF stiffness) and strength factor β (strongback strength/SCBF strength). We conducted nonlinear dynamic analyses to evaluate the effectiveness of α and β on structural demand parameters including maximum drift ratio and drift concentration factor (DCF). Analyses results show that although strongback system with excessively high α and β will reduce maximum drift ratio and DCF of SCBF systems, it is noneconomic. On the other hand, strongback systems with low α and β (α<0.0048 and β<0.054) have only little effects on improving structural behavior. The case studies suggested that 0.0096≤α≤0.0168 and 0.081≤β≤0.134 accounting for both efficiency and economics can be used in the design of the selected SCBF systems.

Seismic performance of single-storey steel concentrically braced frame structures constructed in the 1960s

2014 ◽  
Vol 41 (7) ◽  
pp. 579-593
Author(s):  
A. Caruso-Juliano ◽  
A. Gallagher ◽  
T.E. Morrison ◽  
C.A. Rogers
Keyword(s):  
Seismic Performance ◽  
Fragility Curves ◽  
Failure Criteria ◽  
Braced Frame ◽  
Block Shear ◽  
Concentrically Braced Frame ◽  
Moderate Seismicity ◽  
Concentrically Braced ◽  
Dynamic Analyses ◽  
The 1960S

A general overview of the seismic performance of representative single-storey concentrically braced frame (CBF) buildings designed using the 1965 National Building Code of Canada and the 1965 S16 Canadian Standards Association Steel Structures for Buildings Standard was obtained through the use of nonlinear time history dynamic analyses and the testing of brace elements obtained from buildings constructed in the 1960s. The study comprised 16 representative buildings subjected to 20 site selected ground motions for three locations; Halifax (Nova Scotia) low seismicity, Montreal (Quebec) moderate seismicity, and Abbotsford (British Columbia) high seismicity. Incremental dynamic analyses were performed using various failure criteria as obtained from the test data; brace net-section fracture, bolt shear, block shear, bolt bearing and brace yielding. Fragility curves were created and the probability of failure was defined. The performance of the structures designed for Abbotsford was unsatisfactory for all of the brace connection failure mechanisms. In contrast, because of the lower current seismic hazard in Montreal, the 16 archetypical buildings demonstrated better performance. In Halifax the buildings performed well, based on the identified failure criteria. It was necessary to strengthen the roof diaphragms for all buildings to carry 2010 NBCC design level seismic forces.

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