Performance-based Methodology Research Articles

Autism spectrum disorder - the fight of the public against a disease it fails to understand.

Madam, Autism is a heterogeneous set of neurodevelopmental conditions affecting around 1% of the population globally [1,2] and every 1 in 120 people in Pakistan [5]. It exhibits a higher incidence in males than females [1,2,5]; this may be because males have a lower threshold for brain dysfunction, and require a lower genetic burden to cause autism, than females. Individuals with autism commonly experience impaired social cognition and perception, atypical information processing, and restricted patterns of behaviour and interest. A study from The Lancet in 2014 determined that the autism goes hand in hand with multiple other intellectual, psychiatric, medical, and behavioural disorders, with a significant association between autism and motor abnormality, sleep disorders, and aggressive behaviours [1]. While multiple genetic and developmentally early environmental factors have been established as risk factors in the aetiology of autism, none were confirmed to be adequate alone for ASD to develop. With respect to familiarity with autism, while people are not completely unaware of the existence of the disease they do display poor knowledge about its symptoms and presentation. In a study conducted in Pakistan in 2012, 52 out of the 73 teachers who participated (71%) claimed to have knowledge regarding autism; substantial gaps were recognized in their perceived knowledge about the disease [3]. Another study conducted in Karachi also concluded that parents’ lack of awareness and insufficient knowledge among parents about the signs and symptoms as well as the treatment and diagnosis of autism [4]. Early diagnosis is crucial for timely intervention; the assessment of children needs to be developmental and multidisciplinary [1]. Even though multiple rating scales and checklists have been established, it is preferable to use more performance-based methodologies for assessment and diagnosis [2]. Thorough and focused behavioral interventions in early life can promote social communication and decrease aggression and anxiety in individuals diagnosed with ASD. Support should be personalized according to each individual and if feasible, should be multi-dimensional. Although drugs as a form of treatment diminish comorbid symptoms in autistic people, they alone display no direct effect on enhancing social communication. Awareness can be spread by donating or volunteering at fundraisers, through social media, and by participating in various autism programs. Formation of an encouraging environment that acknowledges and respects that the individual is different is imperative.

Defining the fire decay and the cooling phase of post-flashover compartment fires

The current research study discusses and characterises the fire decay and cooling phase of post-flashover compartment fires, as they are often mixed up despite their important heat transfer differences. The two phases are defined according to the fire heat release rate time-history. The fire decay represents the phase in which the fire heat release rate decreases from the ventilation- or fuel-limited steady-state value of the fully-developed phase to fire extinguishment. This phase is highly influenced by the fuel characteristics, ranging from fast decays for hydrocarbon and liquid fuels to slow decays for charring cellulosic fuels (wood). Once the fuel is consumed, the compartment volume enters the cooling phase, where the cooling in the gas-phase and solid-phase happens with significantly different modes and characteristic times. The thermal boundary conditions at the structural elements are then defined according to physical characteristics and dynamics within the compartment. The research study also underlines how the existing performance-based methodologies lack explicit definitions of the decay and cooling phases and the corresponding thermal boundary conditions for the design of fire-safe structural elements under realistic fire conditions.

Effect of buoyancy loads on the tsunami fragility of existing reinforced concrete frames including consideration of blow-out slabs

Currently available performance-based methodologies for assessing the fragility of structures subjected to tsunami neglect the effects of tsunami-induced vertical loads due to internal buoyancy. This paper adopts a generalized methodology for the performance assessment of structures that integrates the effects of buoyancy loads on interior slabs during a tsunami inundation. The methodology is applied in the fragility assessment of three case-study frames (low, mid and high-rise), representative of existing masonry-infilled reinforced concrete (RC) buildings typical of Mediterranean region. The paper shows the effect of modelling buoyancy loads on damage evolution and fragility curves associated with different structural damage mechanisms for existing RC frames with breakaway infill walls including consideration of blow-out slabs. The outcomes attest that buoyancy loads affect the damage assessment of buildings during a tsunami, especially in the case of mid and high-rise structures with blow-out slabs. The rate of occurrence of slabs uplift failure increases with the number of stories of the building, indicating the need to account for such damage mechanism when assessing the performance of structures. It is also found that buoyancy loads slightly affect the fragility curves associated to other structural damage mechanisms for existing RC buildings commonly monitored for fragility assessment.

A CFD based methodology to design an explosion prevention system for Li-ion based battery energy storage system

This work developed a performance-based methodology to design a mechanical exhaust ventilation system for explosion prevention in Li-Ion-based stationary battery energy storage systems (BESS). The design methodology consists of identifying the hazard, developing failure scenarios, and providing mitigation measures to detect the battery gas and maintain its global concentration lower than 25% of the lower flammability limit (LFL) to meet the prescriptive performance criterion of NFPA 69 – Standard on Explosion Prevention Systems. Representative UL 9540A test data is used to define the battery gas composition, release rate, and release duration to describe the failure scenario involving thermal runaway propagation. In addition, an exemplar BESS enclosure geometry is defined to model the failure scenarios using a computational fluid dynamics (CFD) solver. A grid convergence study is performed to estimate the grid resolution required to perform the CFD analysis. In addition, sensitivity studies for different input parameters are performed to understand the impact of inputs on the detection times and ventilation performance. The approach used in this work provides a systematic procedure for the fire protection engineering community to understand the explosion prevention requirement for a BESS installation. The explosion prevention system functionality presented in this work is limited to removing flammable battery gas generated due to the non-flaring decomposition of batteries.

Seismic fragility assessment of building-type structures in oil refineries

A seismic fragility assessment methodology is presented for equipment-supporting reinforced concrete and steel buildings that are typically encountered in oil refineries. Using a suite of hazard-consistent ground motions and reduced-order models, incremental dynamic analysis is performed to obtain the seismic demand of the structural systems examined. Appropriate drift- and floor acceleration-sensitive failure modes are considered to define the limit state capacities of the supporting structure and the nested non-structural process equipment. Special care is exercised on the demand and capacity representation of structural and non-structural components, offering a transparent roadmap for undertaking analytical fragility assessment for equipment-supporting buildings typical to an oil refinery. The findings and the proposed methodology can be exploited by designers and facility managers for mitigating the risk of failure prior to the occurrence of an earthquake event, for designing the pertinent structures and their non-structural components by means of a risk-aware performance-based methodology, or as feed data in early warning systems.

Multi-objective optimization for probabilistic performance-based design of buildings using FEMA P-58 methodology

This research presents an automated performance-based optimal design process by integrating a multi-objective optimization algorithm and a comprehensive probabilistic performance assessment method. This process is used to provide a set of design options that comply with the minimum code requirements and are optimal in terms of both initial cost and mean annual repair cost. The FEMA P-58 methodology is utilized as a modern performance-based methodology to determine the various performance measures such as repair costs, repair time, casualty rates, environmental impacts, and unsafe placarding for the design alternatives. To account for uncertainties in the magnitude and intensity of future earthquakes, the time-based assessment, and to account for inherent uncertainties affecting seismic performance, the Monte Carlo procedure is performed in accordance with FEMA P-58 guideline. The optimization process is carried out using a well-known multi-objective optimization algorithm called NSGA-II for three example office buildings with 3-, 6- and 9-story steel moment frame structures. For each building, a detailed performance model including a set of fragility functions for the structural and non-structural components as well as contents typically present in the building is considered. Three optimal design options are selected from the Pareto front set obtained for each building based on different optimization objectives. They are compared with each other and with the other design alternatives in terms of various performance metrics under different ground motion intensities. The contribution of structural components as well as drift-, acceleration- and velocity-sensitive non-structural components to the repair costs of these optimal designs is investigated. It is shown that drift-sensitive nonstructural components have the largest contribution to the repair costs of optimal structures. The contribution of these components in earthquake events with a 29% probability of exceedance in 50 years (29%/50 yrs) is on average about 71%, which decreases to 55% with increasing seismic intensity to 3%/50 yrs.

Rehabilitation of reinforced concrete building using the fuseis beam-link system

A methodology is introduced for applying the FUSEIS beam-link steel lateral-load-resisting system for strengthening existing reinforced-concrete buildings. The purpose is to take advantage of the easy replaceability and architectural versatility of the FUSEIS systems to strengthen a deficient structure, while minimizing the economic impact of the rehabilitation works due to suspension of the operation of the building. Additionally, a case study is presented, where an existing building is upgraded by introducing FUSEIS beam-link systems, first by performing response spectra analysis using an initial behaviour factor, then refining the results via the INNOSEIS performance-based methodology. This necessitates the use of nonlinear dynamic analyses to quantify a risk-consistent behaviour factor that incorporates the effect of aleatory and epistemic uncertainty on the actual systems’ performance. Finally, a pre-normative assessment for the q-factor of FUSEIS-beam link systems is achieved, for use in existing reinforced concrete buildings within Eurocode 8.

Seismic damage assessment of unanchored nonstructural components taking into account the building response

The paper presents an extended seismic damage assessment of unanchored nonstructural components by means of rigid block analysis. Both (real) ground and floor motions are considered as loading histories, together with accelerogram inputs developed according to the latest protocols for shake table testing of (acceleration-sensitive) nonstructural components (AC156 and FEMA 461). A performance-based methodology is developed for the damage analysis of the components, also taking into account magnification and filtering actions of reinforced concrete buildings. Fragility curves are evaluated, and the influence of the key parameters on the seismic performance of rocking components is characterized. Floor motions are found to be more severe than (strong) ground motions, except for large blocks under moderate to overturning rocking amplitude (considering ground acceleration-based intensity measures). Strong floor motions are significantly more severe than (strong) ground motions, and they are associated with a relatively reduced record-to-record uncertainty. AC156 protocol produces inputs overall compatible with floor motions, whereas FEMA 461 protocol inputs are more severe and fit better strong floor motions. The severity of the record sets is found to be correlated with the frequency content of the loading histories. The study provided new knowledge and technical insights regarding the seismic damage assessment of unanchored (building) components.

A Performance-Based Airspace Model for Unmanned Aircraft Systems Traffic Management

Recent evolutions of the Unmanned Aircraft Systems (UAS) Traffic Management (UTM) concept are driving the introduction of new airspace structures and classifications, which must be suitable for low-altitude airspace and provide the required level of safety and flexibility, particularly in dense urban and suburban areas. Therefore, airspace classifications and structures need to evolve based on appropriate performance metrics, while new models and tools are needed to address UTM operational requirements, with an increasing focus on the coexistence of manned and unmanned Urban Air Mobility (UAM) vehicles and associated Communication, Navigation and Surveillance (CNS) infrastructure. This paper presents a novel airspace model for UTM adopting Performance-Based Operation (PBO) criteria, and specifically addressing urban airspace requirements. In particular, a novel airspace discretisation methodology is introduced, which allows dynamic management of airspace resources based on navigation and surveillance performance. Additionally, an airspace sectorisation methodology is developed balancing the trade-off between communication overhead and computational complexity of trajectory planning and re-planning. Two simulation case studies are conducted: over the skyline and below the skyline in Melbourne central business district, utilising Global Navigation Satellite Systems (GNSS) and Automatic Dependent Surveillance-Broadcast (ADS-B). The results confirm that the proposed airspace sectorisation methodology promotes operational safety and efficiency and enhances the UTM operators’ situational awareness under dense traffic conditions introducing a new effective 3D airspace visualisation scheme, which is suitable both for mission planning and pre-tactical UTM operations. Additionally, the proposed performance-based methodology can accommodate the diversity of infrastructure and vehicle performance requirements currently envisaged in the UTM context. This facilitates the adoption of this methodology for low-level airspace integration of UAS (which may differ significantly in terms of their avionics CNS capabilities) and set foundations for future work on tactical online UTM operations.

Computational implementation of part stiffness on tolerance specification based on the functional performance of assemblies

One of the most critical tasks within the scope of Design for Manufacturing (DfM) is to define the set of Geometrical Product Specifications (GPS) in the 3D model or in the engineering drawing that ensures the functionality and the interchangeability of parts, as well as the intended functional performance of an assembly. Several methodologies have been proposed for the optimal designation of such specifications; however, the majority of them do not effectively take into account the deformations that are inevitably induced during assembly and operation for the vast majority of mechanical components. Motivated by the widely accepted tolerancing practice for sheet metal parts in the automotive industry, where the distinction between free state and constrained state is considered, the paper investigates the influence of the deformations induced during assembly and operation on GPS. The effect of part stiffness in the resultant functional GPS of the assembly/component is explored, through CAD surfacing and non-linear numerical finite element analysis tools including the contact problem. The current stage of development of a novel, performance-based methodology for the GD&T design procedure is presented. The methodology is applied on a real-world mechanical assembly that is derived from tolerance stack up-related literature. This study illustrated is that for an unpredictably wide range of mechanical components the default, free-state GPS scheme should only be assigned after rigorous analysis of their compliance behaviour. The proposed approach will lead to deduce the correlation between production cost and performance through a further development in future study.

Role of Aggregate Gradation in Balancing the Performance of Asphalt Concrete Mixtures

Improving the durability and long-term performance of asphalt concrete (AC) has become a major concern, especially with the increase in the use of recycled materials, warm mix asphalt additives and modified binders. This paper presents an evaluation of different mix design approaches to balance the mechanical properties of AC mixtures. The current volumetric-based design method was enhanced with a performance-based analysis methodology that specifies the parameters from the overlay tester, Hamburg wheel tracking device and indirect tension tests. Two typical Superpave mixes from different plants that exhibited a poor performance, especially in cracking, were selected for this evaluation. The mixtures were first designed following the current volumetric-based design process and characterized under the proposed performance-based analysis. Two alternative approaches that consider the influence of the asphalt content and the aggregate gradation were explored to improve the engineering behavior of the mixtures. From this evaluation, two mixtures that could potentially yield optimal volumetric and balanced mechanical properties were developed. The optimization of the aggregate gradation is a promising approach to formulate a mixture with a balanced stability and durability, as judged by its rutting and cracking potentials.

Performance enhancement of unfalsified adaptive control strategy using fuzzy logic

ABSTRACTUnfalsified Adaptive Switching Supervisory Control (UASSC) is a performance-based data-driven methodology to control uncertain systems with the least possible plant assumptions. There are a set of pre-designed controllers in the controller bank, and the goal is to select the best controller at each time instance. The Multi-Model UASSC (MMUASSC) uses the UASSC concept, but it also benefits from a set of pre-specified models in the model bank. This paper introduces a method to improve the performance of the UASSC and MMUASSC by cost function manipulations and fuzzy logic concepts. To achieve this, fuzzy UASSC and fuzzy MMUASSC methods are introduced. In these methods, a time-varying coefficient, which is the output of a fuzzy system, is used along with the conventional cost functions. The input of this fuzzy system is chosen to properly reflect the performance of the corresponding controller in the controller bank. Using this method, the performance of the outside loop controllers is accurately evaluated, and closed-loop stability proof is provided. Also, as the existence of non-minimum phase controllers is problematic, a solution is provided to handle such cases. Finally, simulation results are used to show the effectiveness of the introduced methods.

Performance-Based Assessment Methodology for Retrofit of Buildings

Postearthquake reconnaissance and recent research on seismic risk analysis have shown that nonductile concrete frame structures are much more susceptible to collapse than modern code-conforming frames. The performance-based assessment paradigm has been a persistent research theme over the last decade within the earthquake engineering community in order to estimate seismic fragilities and earthquake loss for these nonductile concrete frames. This paper proposes a nonlinear performance-based methodology to evaluate different retrofit methods considering hazard level, target performance levels, and life-cycle cost estimates. The structural performance is the main parameter considered for the optimization, although a life-cycle cost analysis is also presented. As a case study, the longitudinal frame of an existing building was modeled considering the effect of flexural-shear-axial load interaction in order to capture column shear and axial failures. The presented performance-based procedure identifies the most economic retrofit solution that satisfies structural response requirements for a given performance level.

Strength prediction and mix design procedures for geopolymer and alkali-activated cement mortars comprising a wide range of environmentally responsible binder systems

ABSTRACTThis research presents a mix design methodology for geopolymer (GP) and alkali activated (AA) mortars based on metakaolin and industrial waste products activated using potassium silicate. The aim is to enable a wide range of mix designs to be specified to given compressive strength, consistency and environmental footprints to facilitate their adoption as a Portland cement (PC) alternatives in the construction industry in applications such as fibre-reinforced building cladding systems. The impact of the work is timely as literature quantifying the effects of mix parameters on broad families of GP and AA materials are limited, and no standardized performance-based methodology exists. Initially, effects of binder composition on mechanical and environmental properties are presented for a standard GP mix design using contoured ternary plots for a range of material blends. Next, effects of altering mixture parameters such as liquid/solid, silica/alumina and activator/binder ratios are quantified for three selected binder compositions before a preliminary mix design methodology is presented allowing initial selection of mixture proportions. Finally, correlation analysis is used to identify multiple mix variables strongly correlating with strength, and regression modeling used to present predictive tools with average errors <6%.

Performance-based design method of steel-to-concrete post-installed connection under combined action of earthquake and fire

ABAQUS software was first used to study the structure behaviour of steel-to-concrete connection by post-installed anchorage under cyclic loading. Three types of embedment depth 25d, 20d and 15d were considered. Based on previous simulation results of earthquake and fire, it can be concluded that the seismic performance of steel-to-concrete connection by post-installed anchorage is strongly related to the rotation angle 0 of steel beam. The heat analysis results indicate that the fire resistance of post-installed connection after 2 hours exposure could meet the requirement of related codes. Based on the simulation results mentioned above, a performance-based design conception with four performance levels has been provided to guarantee structure safety under the combined action of earthquake and fire. According to the principle of performance-based methodology, rotation angle 0 of steel beam and fire resistance rating T are chosen as critical index for performance evaluation. Among the 4 levels of performance, Level 1 has the highest specification for disaster protection. To achieve the performance level 1, the thickness of fire protection layer should not be less than 45 mm, and the embedment depth should be 25d at least.

Concurrent, Performance-Based Methodology for Increasing the Accuracy and Certainty of Short-Term Neural Prediction Systems.

Accurate prediction of the short time series with highly irregular behavior is a challenging task found in many areas of modern science. Such data fluctuations are not systematic and hardly predictable. In recent years, artificial neural networks have widely been exploited for those purposes. Although it is possible to model nonlinear behavior of short time series by using ANNs, very often they are not able to handle all events equally well. Therefore, alternative approaches have to be applied. In this study, a new, concurrent, performance-based methodology that combines best ANN topologies in order to decrease the forecasting errors and increase the forecasting certainty is proposed. The proposed approach is verified on three different data sets: the Serbian Gross National Income time series, the municipal traffic flow for a particular observation point, and the daily electric load consumption time series. It is shown that the method can significantly increase the forecasting accuracy of the individual networks, regardless of their topologies, which makes the methodology more applicable. For quantitative comparison of the accuracy of the proposed methodology with that of similar methodologies, a series of additional forecasting experiments that include a state-of-the-art ARIMA modelling and a combination of ANN and linear regression forecasting have been conducted.

Virtual Reality as an Emerging Methodology for Leadership Assessment and Training.

In developed countries, companies are now substantially reliant on the skills and abilities of their leaders to tackle a variety of complex issues. There is a growing consensus that leadership development training and assessment methods should adopt more holistic methodologies, including those associated with the emotional and neuroendocrine aspects of learning. Recent research into the assessment of leadership competencies has proposed the use of objective methods and measurements based on neuroscience. One of the challenges to be faced in the development of a performance-based methodology to measure leadership skills is how to generate real-life situations with triggers that allow us to study management competencies under controlled laboratory conditions. A way to address this question is to take advantage of virtual environments to recreate real-life situations that might arise in performance-based assessments. We propose virtual reality (VR) as a very promising tool to observe various leadership related behavioral patterns during dynamic, complex and realistic situations. By seamlessly embedding assessment methods into virtual learning environments, VR can provide objective assessment methods with high ecological validity. VR also holds unlimited opportunities for leadership training providing subjects with intelligent tutoring systems that adapts situations in real time according to the observed behaviors.

Design Development of a Four-Story Strongback Braced Frame

Conventional braced frames tend to concentrate damage in one or a few stories during large earthquakes, indicative of “weak” or “soft” story behavior. To mitigate this behavior, several studies have proposed a modified braced frame, or “strongback”, that utilizes an essentially elastic vertical steel truss to impose a uniform drift distribution. While a subassemblage experimental test and past numerical studies have shown that the strongback system can successfully delay or prevent weak or soft story behavior, the dynamic behavior of this system has not been systematically assessed or evaluated. This study defines the design space for a four-story strongback system. The ability of the strongback to mitigate weak story behavior under a far-field suite of ground motions was assessed using the performance-based methodology in FEMA P695.

Design and performance prediction of timber bridges based on a factorization approach

ABSTRACTService life of timber bridges is predominantly affected by the site-specific climatic conditions in terms of moisture and temperature over time, the overall design, the design of details, and the choice of materials. In recent years, a performance-based methodology has been developed to predict (1) the material climatic conditions within timber components from macro climate data and comparison between design details, (2) decay intensity from material climate data, and (3) the material resistance as a combined effect of wood-inherent properties and its moisture dynamics. Within the WoodWisdomNet project ‘Durable Timber Bridges’ we emphasized on utilizing exposure, decay, and resistance models for a comprehensive guideline for the design of timber bridges. Therefore, a factorization approach is presented based on dose–response relationship between wood material climate and responding fungal decay. The concept does also allow for quantifying the material resistance of untreated, modified, and preservative-treated wood using factors based on laboratory and field durability tests and short-term tests for capillary water uptake, adsorption, and desorption dynamics. The findings from the present study have the potential to serve as an instrument for design and service life prediction of timber structures and will be implemented in an engineering design guideline for timber bridges.

Reimagining Performance in Public Administration Theory and Practice: Creating a Democratic Performativity of Care and Hope

Public administration scholars and practitioners for too long have understood the concept of performance almost exclusively in terms of the neoliberal, new public management project where it is defined by reference to the measurement of outcomes. Borrowing from the “performance turn” in the human sciences, this article proposes reimagining performance as a critical and cultural concept that refers both to what is done (or performed) and to the doing of what is done (performativity). From this perspective, performance becomes a concept by which public administration scholars might not just measure, but rather interrogate critically and deeply, how effectively and to what ends public policies, leaders, and administrators perform social justice, inclusivity, care, and other democratic values. This concept of performance introduces new expressive performance-based theories, methodologies, and pedagogies to public administration scholarship and teaching that could help advance the project of creating a hopeful, democratic, and caring performing state for the twenty-first century.