Comparative study on the response of RC frame structure braced with different steel bracing systems
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Date
2016-10
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Addis Ababa University
Abstract
Multistory buildings are mostly affected by earthquake force in seismic prone area. The major concern in the design of multistory building is the structure mainly to have enough lateral stability to resist lateral forces and to control the lateral drift of the buildings. The steel bracing system in reinforced concrete frames is viable for resisting lateral forces, steel bracing is easy to erect occupies less space and has flexibility in design for meeting the required strength and stiffness.
In this study to know the importance of different bracing systems in the multistory RC frame structure a linear analysis of different story buildings are considered i.e., 4story (G+3), 6story (G+5), 9story (G+8), and 13story (G+12) of three bays by five bays RC building for seismic zone IV have been analyzed with four different types of steel bracing at the exterior of the frame in the same location and the same pattern. The bracings studied are diagonal brace, X-brace, V-brace and inverted V-brace (chevron brace) and performance of each frame has been carried out using linear static analysis.
Two types of arrangements has been used;3x1braced (3bays out of 5 and 1bay out of 3 are braced) and corner braced (corners are braced in all direction) and all frames are analyzed without bracing and with all types of bracing, a total of 40 different models are analyzed and compared using nonlinear finite element software ETABS 2015. Lateral story displacement, seismic base shear, and story drift of braced frames have been evaluated and compared with bare frame. The percentage reduction in lateral displacement and story drift is found out and also the increase in the seismic base shear and base moment capacity after the applications of all bracing.
Inverted V-bracing (chevron bracing) and X-bracing show the best performance in reduction of lateral displacement and story drift. X-bracing type is found to be the most in increasing the shear capacity of RC frame building which indicates that the X-brace type of steel bracing significantly contributes to the structural stiffness. Corner braced arrangement has shown better result in reduction of lateral displacement than 3x1 braced. From the analysis result one can
Comparative study on the response of RC frame structure braced with different steel bracing systems
(AAU/AAiT,SCEE MSc Thesis) ,2016 ii
conclude that both X-bracing and Inverted-bracing system may be used to in new building or to retrofit existing damaged building. However, X-bracing system is more suitable to use.
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Structural Engineering