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PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY
Edited by: B.H.V. Topping and M. Papadrakakis
Optimization of Masonry Infilled Reinforced Concrete Buildings
I.A. Naziris, N.D. Lagaros and M. Papadrakakis
Institute of Structural Analysis & Seismic Research, National Technical University of Athens, Greece
I.A. Naziris, N.D. Lagaros, M. Papadrakakis, "Optimization of Masonry Infilled Reinforced Concrete Buildings", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 198, 2008. doi:10.4203/ccp.88.198
Keywords: performance-based design, masonry infill walls, life-cycle cost analysis, reinforced concrete buildings, structural optimization, evolutionary algorithms.
The majority of the reinforced concrete (RC) buildings are infilled with masonry walls. However, in most of the contemporary design procedures the combination of masonry infills with the framed structure is neglected, assuming that the influence of the infill walls on the structural performance is always positive. Such an assumption may lead to inaccurate prediction of the lateral stiffness, strength and ductility of the structure, and thus obtain unacceptable designs. In the past, a number of studies have been performed on the seismic behaviour of RC buildings with masonry infill walls and a number of analytical models for the masonry infills have been developed for a rational design of RC framed structures [1,2,3].
In the last decade the concept of performance-based design (PBD) for structures subjected to seismic loading conditions was introduced. ATC-40  and FEMA-273  were the first guidelines for performance-based seismic rehabilitation of existing buildings while in the report Vision 2000  these ideas were extended to the design of new buildings. The main objective of these kinds of design procedures is to achieve predictable and reliable levels of safety and operability against natural hazards.
The present study examins the influence of the masonry infill walls in the framework of performance-based optimum design of reinforced concrete buildings. The construction practices that are examined are the bare frame, the fully infilled frame and the weak ground storey case (Pilotis). Nonlinear static and nonlinear dynamic procedures are implemented into the framework of performance-based structural design optimization in order to define an automatic seismic design methodology for taking into account the influence of infill walls. The designs obtained through this methodology are assessed performing life-cycle cost analysis where it was found that ignoring the influence of infill walls lead to designs that exhibits poor performance in future earthquakes.
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