Seismic Performance of Dual Systems with BRBs under Mainshock-Aftershock Sequences

Buckling-restrained braces (BRBs) are employed in new constructions and in the retrofitting of existing frames. They provide additional strength and stiffness to buildings, together with high and stable energy dissipation capacity. BRBs can fail due to excessive maximum and/or cumulative ductility demands. In addition, the use of BRBs can result in large residual drifts in the structure due to their low post-elastic hardening. Moreover, in seismic-prone regions, structures are usually subjected to mainshock-aftershocks (MS-AS) earthquake sequences, often leaving no time for repair or retrofit between events. Ductility demand accumulation and/or residual drifts induced by the MS can affect the structural performance during the following AS. The present study addressed the abovementioned issues by first investigating an optimal design procedure for steel dual systems in which conventional BRB frames are combined with moment-resisting frames. The latter are designed to behave elastically to enhance the self-centering capability of the structure and limit soft-story mechanisms. The design procedure is first presented and applied to a case-study building. The seismic performance of the latter is assessed by means of sequential Cloud Analysis. Both real and artificial MS-AS sequences are used to derive system fragility curves. Results show that the BRBs capacity can be potentially affected by multiple earthquakes, which cause accumulation of plastic strains within the devices. However, the preliminary results show that when accounting for real MS-AS sequences, ASs do not significantly increase the cumulative ductility demands in BRBs.The support of Prof. Katsuichiro Goda that provided real MS-AS sequences, as well as the fruitful discussions on the detailed BRBs OpenSees modeling with Prof. Alessandro Zona and Prof. Quan Gu are gratefully acknowledged

Seismic Performance of Dual Systems with BRBs under Mainshock-Aftershock Sequences

Buckling-restrained braces (BRBs) are employed in new constructions and in the retrofitting of existing frames. They provide additional strength and stiffness to buildings, together with high and stable energy dissipation capacity. BRBs can fail due to excessive maximum and/or cumulative ductility demands. In addition, the use of BRBs can result in large residual drifts in the structure due to their low post-elastic hardening. Moreover, in seismic-prone regions, structures are usually subjected to mainshock-aftershocks (MS-AS) earthquake sequences, often leaving no time for repair or retrofit between events. Ductility demand accumulation and/or residual drifts induced by the MS can affect the structural performance during the following AS. The present study addressed the abovementioned issues by first investigating an optimal design procedure for steel dual systems in which conventional BRB frames are combined with moment-resisting frames. The latter are designed to behave elastically to enhance the self-centering capability of the structure and limit soft-story mechanisms. The design procedure is first presented and applied to a case-study building. The seismic performance of the latter is assessed by means of sequential Cloud Analysis. Both real and artificial MS-AS sequences are used to derive system fragility curves. Results show that the BRB’s capacity can be potentially affected by multiple earthquakes, which cause accumulation of plastic strains within the devices. However, the preliminary results show that when accounting for real MS-AS sequences, ASs do not significantly increase the cumulative ductility demands in BRBs

INNOVATIONS in earthquake risk reduction for resilience: RECENT advances and challenges

The Sendai Framework for Disaster Risk Reduction 2015-2030 (SFDRR) highlights the importance of scientific research, supporting the ‘availability and application of science and technology to decision making’ in disaster risk reduction (DRR). Science and technology can play a crucial role in the world’s ability to reduce casualties, physical damage, and interruption to critical infrastructure due to natural hazards and their complex interactions. The SFDRR encourages better access to technological innovations combined with increased DRR investments in developing cost-effective approaches and tackling global challenges. To this aim, it is essential to link multi- and interdisciplinary research and technological innovations with policy and engineering/DRR practice. To share knowledge and promote discussion on recent advances, challenges, and future directions on ‘Innovations in Earthquake Risk Reduction for Resilience’, a group of experts from academia and industry met in London, UK, in July 2019. The workshop focused on both cutting-edge ‘soft’ (e.g., novel modelling methods/frameworks, early warning systems, disaster financing and parametric insurance) and ‘hard’ (e.g., novel structural systems/devices for new structures and retrofitting of existing structures, sensors) risk-reduction strategies for the enhancement of structural and infrastructural earthquake safety and resilience. The workshop highlighted emerging trends and lessons from recent earthquake events and pinpointed critical issues for future research and policy interventions. This paper summarises some of the key aspects identified and discussed during the workshop to inform other researchers worldwide and extend the conversation to a broader audience, with the ultimate aim of driving change in how seismic risk is quantified and mitigated

Plan for Profit: An Analysis of the Live Export Trade

The current regime for the export of live animals from Australia is in drastic need of reform. Recent media exposés have brought the brutal nature of the live export trade to light. This trade should be abolished. Thus far, legislative attempts to do so have not succeeded. The current legal regime fails to protect the welfare of animals throughout the live export chain. This article examines the protection of animal welfare in the current regulatory system and highlights its deficiencies. It also makes some proposals for reform. For as long as the trade continues, reform is needed to ensure that animal suffering is minimised

Functional dependencies and constraints on null values in database relations

Database relations with incomplete information are considered. The no-information interpretation of null values is adopted, due to its characteristics of generality and naturalness. Coherently with the framework and its motivation, two meaningful classes of integrity constraints are studied: (a) functional dependencies, which have been widely investigated in the classical relational theory and (b) constraints on null values, which control the presence of nulls in the relations. Specifically, three types of constraints on null values are taken into account (nullfree subschemes, existence constraints, disjunctive existence constraints), and the interaction of each of them with functional dependencies is studied. In each of the three cases, the inference problem is solved, the complexity of the algorithms for its solution analyzed, and the existence of a complete axiomatization discussed

Experiences introducing a measurement program

AbstractMeasurement is an integral part of total quality management and process improvement strategies. This paper describes our experiences using the Goal-Question-Metric (GQM) paradigm to help design a company-wide measurement program for Engineering Ingegneria S.p.A., an Italian software house. The introduction of the measurement program was supported by the Commission of the European Communities within the European Software and Systems Initiative (ESSI) as a Process Improvement Experiment (PIE). We found it necessary to supplement GQM into two ways. Firstly, we defined our measures rigorously in terms of entities, attributes, units and counting rules. Secondly, the original GQM plan was subject to an independent review. The most critical problem identified by the review was that the GQM plan identified too many productivity factors for any statistical analysis to handle concurrently. In order to address this issue, we developed an analysis technique based on a step-wise analysis of residuals. This has allowed us to identify the main factors affecting productivity and effort