Tomeo, Romeo (2017) Soil-structure interaction effects on the seismic behaviour of reinforced concrete structures. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: Soil-structure interaction effects on the seismic behaviour of reinforced concrete structures
Date: 6 April 2017
Number of Pages: 216
Institution: Università degli Studi di Napoli Federico II
Department: Strutture per l'Ingegneria e l'Architettura
Dottorato: Ingegneria strutturale, geotecnica e sismica
Ciclo di dottorato: 29
Coordinatore del Corso di dottorato:
Bilotta, AntonioUNSPECIFIED
Date: 6 April 2017
Number of Pages: 216
Uncontrolled Keywords: Soil-structure interaction; dynamic analyses; reinforced concrete structures
Settori scientifico-disciplinari del MIUR: Area 08 - Ingegneria civile e Architettura > ICAR/07 - Geotecnica
Area 08 - Ingegneria civile e Architettura > ICAR/09 - Tecnica delle costruzioni
Date Deposited: 25 Apr 2017 21:53
Last Modified: 13 Mar 2018 09:15
DOI: 10.6093/UNINA/FEDOA/11537


In common seismic design practice, the design of a new building or the vulnerability assessment of an existing one is usually performed assuming that the structure is fixed at the base and assuming that the signal at the base is that evaluated in free field conditions. This assumption, reasonable for structures founded on stiff soils, can be unrealistic in case of structures founded on soft soils. Despite an intense scientific production on the topic, the diffusion of soil-structure interaction (SSI) analyses in the field of civil constructions is nowadays rather limited, mainly because of three reasons: (1) the lack, in many countries, of specific code prescriptions; (2) the belief that soil-structure interaction has a beneficial effect on the structural response and thus it is possible to have an increase of the safety level neglecting it; (3) the complexity in performing a rigorous analysis. In the thesis these three issues were faced. In order to validate the simplified formulations suggested by American Standards and Guidelines for the evaluation of SSI effects, a sensitivity analysis was performed, by means of linear modal analyses, for Reinforced Concrete (RC) structures (regular and not regular) of different heights and founded on stiff or soft soil. Non-Linear Static Analyses (Push Over) were then performed for two RC Moment Resisting Frames (MRFs) designed without seismic provisions, in order to evaluate the influence of SSI effects on the ratios Capacity/Demand (C/D), which can strongly affect the design strategies of seismic retrofitting interventions. In order to investigate more accurately the influence of SSI effects on the seismic performances of RC MRFs, more refined non-linear dynamic analyses were performed by means of the software OpenSees. The analyses showed that, based on the modelling approach adopted, SSI can affect more or less the estimation of the seismic demand with respect to a fixed-base model. The adoption of a complete FEM model, in which soil and structure are modelled together in one single step, can lead to significant reductions, with respect to a fixed base model, in the estimation of the seismic demand, especially in terms of maximum inter-storey drift ratio. On the contrary, a simplified modelling approach with non-linear springs and dashpots, seems to not adequately capture SSI effects. Moreover, it is emphasized that in case of stiffer structural systems, as dual systems with frames and shear walls, founded on a soft soil, SSI can imply a very high increase of the seismic demand with respect to the fixed base configuration. Thus, SSI effects should be properly taken into account in the design of retrofitting interventions that can involve a strong modification of the structural stiffness.

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