The aim of this paper is to identify the relations between cities and citizens regarding sustainability. We identify clusters of European regions on Sustainable Development Goals based on statistical indicators. We collect and treat data on the ranking of Europeans on Sustainable Development Goals obtained from on-line questionnaires done in different regions in Europe. Using Principal Component Analysist on the composed responses we name them based on the identification of their parts and related their extracted values with the features of the respondents. We conclude not only that the place of the respondents shows significative coefficients in explaining the various components but also that the attitudes implicit in each component favours the goals that are not achieved in the place “People and Places chose what they do not have”.
Issues with traditional implementations of tangent-stiffness-proportional damping model are associated with negative damping forces that develop in the post-yield range when the system stiffness becomes negative and with unrealistic damping forces arising at degrees of freedom undergoing second-order movements only. To overcome these issues, this paper proposes a localized formulation of the tangent-stiffness-proportional damping model which can be used in nonlinear dynamic analysis of simple inelastic systems. Results show the consistency of the local and global damping formulations in small displacements and the effectiveness of the localized tangent-stiffness-proportional damping model in the presence of material and geometrical nonlinearities.
Major earthquakes, such as the Canterbury and Kaikoura events recorded in New Zealand in 2010-2011 and 2016 respectively, highlighted that floor systems can be heavily damaged. Quasi-static cyclic experimental tests of structural sub-assemblies can help to establish the seismic performance of structural systems. However, the experimental performance obtained with such tests is likely to be dependent on the loading protocol adopted. This paper provides an overview of the loading protocols which have been assumed in previous experimental activities, with emphasis on those adopted for testing floor systems. The paper also describes the procedure used to define the loading protocol applied in the testing of a large precast concrete floor diaphragm as part of the ReCast floor project jointly conducted by the University of Canterbury, the University of Auckland and BRANZ. Subsequently the limitations of current loading protocols for bi-directional testing are discussed. The relevance of local seismicity on bidirectional demand is demonstrated by examining a large dataset of records from the RESORCE database. It is concluded that bi-directional experimental testing be undertaken using at least two loading protocols that impose different ratios of demand in orthogonal directions.
P-delta ( PΔ) effects can worsen the seismic performance of building and bridge structures and potentially lead to dynamic instability and collapse. An accurate characterization of PΔ effects is therefore imperative, for both design and assessment of structures. Adopting an earthquake database composed of 7032 ground motions, this article uses the results of a large statistical analysis of amplifications of the displacement demand due to PΔ effects for bilinear single-degree-of-freedom systems to investigate and improve practice-oriented methods to account for PΔ effects. A large range of fundamental periods, ductility levels, and effective heights are investigated, and limits for dynamic instability and negligible PΔ effects are examined in terms of both elastic and inelastic stability coefficients. It is seen that systems with the same stability coefficient present increased PΔ induced displacement amplification with reducing fundamental period and increasing ductility level. New expressions for estimation of the median values of the PΔ displacement amplification ratio are proposed that take into account the combined effect of stability coefficient, ductility level, and fundamental period with improved transition close to dynamic instability. Results of the numerical analyses indicate that the new expressions provide improved accuracy over existing approaches without undue complexity.
ABSTRACT This study proposes a new seismic design procedure for mid‐story isolated structures that reduces design complexity, computational effort, and time. In the proposed procedure, referred to as the coupling coefficients (CCs) method, the isolated superstructure and the substructure are initially treated as decoupled and analyzed separately. CCs are then used to capture the interaction effects among seismic isolation, substructure, and superstructure. We first derived the CCs in closed form using basic concepts of modal analysis. Then, we validate these analytical expressions using statistical results obtained through comprehensive numerical simulations. We described the dynamic problem using mass and stiffness ratios. For stiffness ratios () limited to , and stiffness‐to‐mass ratios ( t ) limited to , simplified expressions for modal periods, masses, participation factors, and damping ratios are developed. A reduced damping in the first mode captures the amplification effects of the substructure on the isolated superstructure. An increased damping in the second mode captures the tuned mass damper effects of the isolated superstructure on the substructure. For small stiffness ratios, the seismic demand of the isolation system can be approximated by that of the independent isolated superstructure on the ground, and the demand of the substructure can be approximated by that of the independent substructure, with adjustments made only for the viscous damping effects.
