Greg Foliente

Parameter Analysis of the Differential Model of Hysteresis

The extended Bouc-Wen differential model is one of the most widely accepted phenomenological models of hysteresis in mechanics. It is routinely used in the characterization of nonlinear damping and in system identification. In this paper, the differential model of hysteresis is carefully re-examined and two significant issues are uncovered. First, it is found that the unspecified parameters of the model are functionally redundant. One of the parameters can be eliminated through suitable transformations in the parameter space. Second, local and global sensitivity analyses are conducted to assess the relative sensitivity of each model parameter. Through extensive Monte Carlo simulations, it is found that some parameters of the hysteretic model are rather insensitive. If the values of these insensitive parameters are fixed, a greatly simplified model is obtained.

Net-zero buildings: incorporating embodied impacts

The design and assessment of net-zero buildings commonly focus exclusively on the operational phase, ignoring the embodied environmental impacts over the building life cycle. An analysis is presented on the consequences of integrating embodied impacts into the assessment of the environmental advantageousness of net-zero concepts. Fundamental issues needing consideration in the design process – based on the evaluation of primary energy use and related greenhouse gas emissions – are examined by comparing three net-zero building design and assessment cases: (1) no embodied impacts included, net balance limited to the operation stage only; (2) embodied impacts included but evaluated separately from the operation stage; and (3) embodied impacts included with the operation stage in a life cycle approach. A review of recent developments in research, standardization activities and design practice and the presentation of a case study of a residential building in Norway highlight the critical importance of performance indicator definitions and system boundaries. A practical checklist is presented to guide the process of incorporating embodied impacts across the building life cycle phases in net-zero design. Its implications are considered on overall environmental impact assessment of buildings. Research and development challenges, as well as recommendations for designers and other stakeholders, are identified.

Multilevel Decision Fusion in a Distributed Active Sensor Network for Structural Damage Detection

Distributed sensor networks are emerging as a critical technical driver in the application of structural health monitoring for large-scale structures as a result of their excellent abilities to enhance the reliability and robustness of monitoring systems. One of the key technical opportunities in the implementation of a distributed sensor network is the application of information fusion. Not only does this enable the integration of data from all sensors for the comprehensive assessment of structural conditions, but it also facilitates the combination of decisions or perceptions from multiple sources or different approaches. In this article, the feasibility of combining a distributed sensor network and several techniques of multilevel decision fusion are demonstrated for damage detection. The level-one decision fusion is first implemented by individual active sensors to create their own perceptions on structural health status. During the fusion process, the active sensors first interrogated local physical sensor nodes in the network, and then combined the perceptions of the local sensors in terms of correlation between features extracted from raw signals and damage scenarios in a knowledge database. Meanwhile, the perceptions of active sensors on structural health status are integrated to represent the decision fusion at level two. Considering the level-two decisions made from different technical approaches, a further combination of all decisions is conducted with implication of information fusion at a higher decision level. As a consequence, the risks of a malfunction of individual sensors or the inappropriateness of individual assessment procedures are significantly reduced, and a robust and error-tolerant structural health monitoring system can be developed. Such an approach is successfully validated by an experimental case study of damage detection in CF/EP composite structures.

Engaging stakeholders in performance-based building: lessons from the Performance-Based Building (PeBBu) Network

Despite decades of recognition and development, performance-based thinking and practice have not been as widely adopted by industry. To address this, the Performance-Based Building (PeBBu) Networks in Europe and Australia engaged a wide variety of industry stakeholders (on both ‘supply’ and ‘demand’ sides) in advancing the application of the performance approach in building processes. The background development, activities and accomplishments of the PeBBu Networks are presented together with some lessons learned from the experience of running the Network programmes. To engage stakeholders effectively, the performance approach should be presented as a business issue rather than primarily as a technical issue. The dominant need is for clear communication of the meaning, application and benefits of the performance approach, with emphasis on actual benefits and value.

A model for predicting household end-use energy consumption and greenhouse gas emissions in Australia

A new tool for predicting the total energy consumption and associated greenhouse gas (GHG) emissions of Australian households is developed by integrating the thermal efficiency of the building envelope, installed equipment and appliances, and different occupancy profiles with energy end-use modules for space heating, space cooling, water heating, lighting, and plug-in appliances. Space heating and cooling energy consumption are simulated by an enhanced version of a house energy rating tool - AccuRate, modified to account for specific heating, ventilation and air-conditioning (HVAC) system efficiency and occupancy profile. Individual modules for hot water, lighting and appliances are developed, calibrated and assessed against available published end-use data in Australia and New Zealand. The tools integrated capability to predict the annual energy consumption of a tenant-occupied house in Melbourne is validated with actual data measured over a 12-month period.

Modeling infrastructure system interdependencies and socioeconomic impacts of failure in extreme events: emerging R&D challenges

Abstract Greater urbanization does not only mean higher concentrations of population and economic activities, but also increasing complexity and infrastructure interdependencies in the delivery of critical urban services such as energy, water, transport and communication. This paper reviews the current literature in these areas and identifies critical research and development challenges from the perspective—and for the benefit—of key stakeholders, considering their primary decision goals and context. From this vantage point, the critical evaluation framework is extended to include a classification of disruptions and extreme events and an overview of infrastructure modeling approaches and broader socioeconomic impacts assessment methods. Mapping the range of modeling and assessment methods against different decision contexts, critical gaps in knowledge and tools are identified to support the latter. Deep uncertainties characterize the challenge as each major component in the information and decision-making chain—from the frequency and intensity of a disruptive event, to assessing the first-order and immediate impacts of an infrastructure failure, to estimating the nature, extent and impact of cascading failures—multiplies the uncertainties. The emerging research challenges to deal with these interdependencies and uncertainties are discussed.

Damage Modeling and Damage Limit State Criterion for Wood-Frame Buildings Subjected to Seismic Loads

Current research trends in residential construction focus on the development of performance-based design methodologies for wood structures. As one key prerequisite to the implementation of such design concept, the performance objectives and their corresponding limit state criteria must be properly defined first. So far, the displacement-based limit state criterion, such as the one proposed in ASCE 41, is the only type of standard available for wood structures. In this paper, damage index-based limit state criterion is proposed for wood-frame buildings. The Park-Ang damage model is used to estimate damage to the wood structures caused by seismic loads. An incremental dynamic analysis-based approach is developed to calibrate the damage model parameter for wood shear wall. To predict the potential damage of wood-frame buildings under future earthquakes, the relationship between calculated damage index and observed building damage is established and validated by experimental test data. The results of this res...

State-of-the-Practice & Challenges in Non-Destructive Evaluation of Utility Poles in Service

In this paper, the state of the practice and challenges in Non-Destructive Evaluation (NDE) of utility poles in service in Australia are discussed. NDE techniques, R&D programs and reliability based maintenance of timber utility poles are reviewed in the context of a systematic asset management system that allows decision-making based on balance of risk and cost. The question is not only which NDE technique should be used, but also when and how the technique should be implemented to provide a cost-effective maintenance strategy. More efforts are needed to develop new or improve existing NDE techniques for more accurate, cost-effective and reliable assessment of utility poles and for better management of these assets.

Knowledge-Mining the Australian Smart Grid Smart City Data: A Statistical-Neural Approach to Demand-Response Analysis

Large scale field trials of smart grid technologies provide important insights as they capture the complex interdependencies of all the key variables, including consumer behaviours, which are needed for their effective evaluation. We present the Australian Smart Grid Smart City program and describe its big data using a narrative approach to hasten understanding and further analyses by others. Then we present a novel statistical-neural approach to maximise knowledge extraction from large datasets of diurnal load profiles, and demonstrate its use in evaluating the effectiveness of two cost-reflective product offerings, a Network-type and a Retail-type product bundle. The methods of analyses include Principal Component Analysis and Self-Organising Mapping. The results for the mid-winter electricity consumption profiles of participating households in July 2013 in New South Wales showed consumption behaviour changes with up to 12 % reduction in relative peak demand at 700 households who accepted the offerings compared to the control group. The resultant load factor of the high consuming outliers improved by about 18 % under demand-response compared to the control group. The feature-based classifier also revealed which behavioural components change due to users’ demand-response activities; results compared favourably with third party consumer survey results.

Modelling building stock energy use and carbon emission scenarios

Purpose – A systematic approach is needed to engage a broad range of stakeholders to reduce greenhouse gas (GHG) emissions from energy use in the building sector. The purpose of this paper is to develop a systems‐based bottom‐up approach for this purpose, and to demonstrate its application in a case study of office building stock in the State of New South Wales (NSW) in Australia.Design/methodology/approach – A conceptual framework for the general method is developed based on a cross‐typology matrix of energy consumption and supply on the one hand, and intervention schemes or policy instruments on the other. This is then tested and demonstrated using a case study of commercial office building stock, with building energy demand calculated using a validated computer energy simulation tool for a representative set of office buildings within a local government area (LGA). The energy consumption and associated GHG emissions are then aggregated up from LGA to the whole State. The impact projections of different...