Search

The effective differentiation between global and local modes plays a fundamental role in the selection and application of the most appropriate seismic analysis procedures. This is particularly relevant in the case of historical heritage structures and ensembles of buildings in old city centres: due to the complexity of the structural scheme, the stratification of interventions, and the irregularity of the structural configuration with the absence of seismic details, several local modes frequently characterize the dynamic response of those structures. Distinguishing local and global modes might be challenging even from the experimental point of view in the presence of few measured degrees of freedom. Nevertheless, an accurate analysis of local modes can support the identification of macro-elements and the selection of the most appropriate analysis procedure. The present paper illustrates an original approach addressing the differentiation between global and local modes through the spatial correlation of modal displacements. The proposed approach can be either automated and integrated into software for structural analysis or applied in the context of an experimental campaign, and its application to simulated case studies is discussed. [ABSTRACT FROM AUTHOR]

Negative bending moments arise near the intermediate supports in continuous beams; thus, when steel-concrete composite beams are considered, tensile stresses act on the concrete slab. As a result the structural response generally becomes nonlinear due to two main effects: the slip at the slab-profile interface and cracking in the concrete slab. In the present paper a method of analysis for continuous composite beams based on a specific kinematic model of the cross section is proposed. The main feature of the model is the capability to take into account the slip at the slab-profile interface and the slip at the concrete-reinforcement interface. This approach allows the introduction of a constitutive relationship for bond between reinforcing bars and concrete in the theoretical analysis; thus, the tension stiffening effect in the negative bending moment regions can be computed, and the actual mechanical behavior of reinforcing bars of the slab can be analyzed. The results of numerical analyses are compared with experimental data, showing very good agreement and the capacity of the model to simulate the main aspects of the structural behavior of composite beams.