Component modeling of PR composite frames under cyclic and dynamic loading. Numerical analyses.

The results of a series of parametric analyses on PR composite frames utilizing an original component mechanical model are presented. The frames analyzed were designed based on the Eurocode provisions for composite structures and seismic design. Each of the analyses focused on a particular aspect of the PR composite joints and frames behaviour, including the influence of (1) column web shear deformation, (2) load factor for live loads to be used in combination with earthquake loads, (3) ductility demands on individual joint components for a given overall ductility factor, and (4) higher modes on the deformation behaviour. The parametric studies on multi-story regular and irregular (i.e., with uniform and different span lengths, respectively) 2D frames confirmed the advantages inherent in the adoption of the mechanical modeling approach in terms of both computational efficiency and simulation of behaviour. The results show that the column web panel in shear, when not stiffened, can become a very influential component both on the local and overall behaviour of the structure. The results also show that the increase of the applied live load during a seismic event is not necessarily a detrimental factor, and can in some cases even be beneficial. Finally, the results also indicate that higher modes can play a key role in the overall behaviour of PR frames subjected to seismic action. The seismic effects calculated basing on the first natural frequency only might not be conservative, and might lead to an erroneous evaluation of the overall structural behaviour.