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Authors
Advisor(s)
Abstract(s)
In the design of structures under seismic actions several methodologies can be
used to describe the structural seismic response. The recent role of performance
based design led to the development and use of methods based on non-linear
analysis, namely the so-called pushover analysis. This analysis is a particularly
realistic methodology to evaluate the seismic performance of a structural system
since the time dependence of the structural behaviour, namely through material
and/or geometric non-linearity, is included in the methodology.
The pushover analysis is a simplified methodology to obtain the structural
response to seismic actions through a non-linear static analysis. This analysis
evaluates the performance of the structures through control of its displacements (at
local and global levels), still giving information about the ductility and the resistant
strength capacity. Several analysis methods have been proposed like the N2-method
(Fajfar and Fischinger [1]) that is actually presented in Eurocode 8 (EC8) [2].
The implementation of this methodology in this regulation manifests the
relevance of this analysis in the structural design. Therefore, the present study was
developed to compile some information about this new dynamic structural analysis
and design concept. In this context, the main objective of this work consists on the
presentation of the above-mentioned method with some numerical applications to
steel (Cesar and Barros [3]) and RC structures (Pereira, Barros and Cesar [4] [5]).
The steel structures (3, 6 and 10 floors) were modelled using the commercial
FEM package MIDAS/Civil, and for each structure three structural resisting
solutions (one solution without bracing and two bracing solutions) were considered:
(i) the structure is built without any bracing element; (ii) the building presents glass
facades and a bracing system composed by diagonals in X-braces; (iii) the building
presents glass facades and the bracing system, by architectural or by strength
Performance Based Design Of Building Structural Frames
Using Static Non-Linear Analysis
R.C. Barros1 and M.B. Cesar2
2 Faculty of Engineering of the University of Porto (FEUP)
Department of Civil Engineering, Porto 4200-465, Portugal
1 Polytechnic Institute of Bragança (IPB-ESTiG)
Department of Applied Mechanics, Bragança 5301-857, Portugal
2
reasons, is constituted by K-braces. Based on this study it was verified that the
bracing system increase the overall inelastic performance compared with the frames
without these bracing systems as can be verified in this study. As expected lower top
displacement are obtained with the corresponding decrease in the inelastic range.
The pushover analysis can be an easy and efficient technique to study the
response of R/C buildings under seismic actions. In this case, the sequence of
component cracking, yielding and failure, as well as the deformation pattern and
shear evolution in the structure, can be traced as the lateral loads or displacements
are increased. To complete the study several RC frames with and without masonry
infill panels were analyzed based on some numerical models proposed in
commercial software.
The study that was carried out was based in the concept of equivalent tie and
several configurations of a regular R/C frame were analyzed. It is intended to
simulate several asymmetries in order to compute the structural performance of each
configuration and compare the resistant capacity evolution during the pushover
procedure. The nonlinear static Pushover analyses used and compared three software
packages.
In these analyses it was verified that this pushover methodology allows
evaluating the performance of structures through control of their displacements (at
local and global levels), still giving additional information about the ductility and
the resistant capacity.
Description
Keywords
Pushover Static non-linear analysis Performance based design Dynamic analysis Bracing system
Citation
Barros, Rui; Braz-César, M.T. (2010). Perfomance based design of building structural frames using static non-linear analysis. In Topping, B.H.V. [et al.] Developments and Applications in Computational Structures Technology. ISBN 978-1-874672-47-0. p.269-308