| Περίληψη: | The present dissertation investigates the redistribution of internal forces among the vertical elements of reinforced concrete (R/C) simple low-rise asymmetrical structures under seismic loading considering Soil-Structure Interaction (SSI).
A series of one-storey R/C plane frames with one, two and four spans, founded οn rigid, deformable soil through footings with connecting beams is analyzed dynamically. The seismic loading is simulated through synthetic accelerograms compatible with the EC8 design spectrum. Οne-storey and three-storey one-span R/C framed 3-D buildings founded οn rigid, deformable soil through footings with connecting beams and foundation mat are dynamically analyzed using real accelerograms.
Asymmetry in the R/C 2-D and 3-D buildings considered is achieved by replacing one of the columns by a wall of variable width. The behavior of R/C elements is considered as elastic according to current design codes, as well as elastoplastic according to an elastoplastic mechanical fiber model. Both linear and nonlinear elastoplastic analyses are performed in the time domain. Linear analyses are done by taking into account reduced member stiffness due to concrete cracking. Nonlinear elastoplastic analyses are done with a concentrated plasticity model with stiffness reduction.
Nonlinear response quantities include not only member moment and shear forces but also interstorey drift ratios and various damage indices at member and structure levels for four performance levels. Dimensionless ratios of internal absolute maximum forces and moments of vertical R/C elements are expressed in terms of their cross-section properties and compared for the cases of SSI and rigid soil for both elastic and elastoplastic analyses. Thus, the influence of SSI on the seismic response of the vertical elements and the whole structure is determined and discussed.
All the analyses prove that SSI strongly affects the seismic response of R/C elements and simple R/C structures and its influence may be beneficial or detrimental in contrast to current codes considering only its positive effects.
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