107 research outputs found

    A New Normative Workflow for Integrated Life-Cycle Assessment

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    In order to curtail energy use by the building sector, consideration of how a sustainable building is constructed is paramount, in many respects, to how efficiently it operates over its lifetime. A typical building must be in use for decades before the energy expended in its daily operations surpasses the energy embodied within its initial construction, as a result of the materials used. More vitally: every building has specific vulnerabilities, particularly to hazards (e.g., earthquakes, wind, flooding) whose effects on sustainability are not explicitly considered alongside other aspects of sustainability in the design process – despite the significant environmental impact of damage and repairs after a disaster. Unfortunately, the joint consideration of resilience and sustainability in design is far from trivial, requiring various interdisciplinary perspectives involved in the delivery of building projects. These perspectives each contribute the models and data necessary for integrated evaluation, leading to the notorious challenges of BIM and data interoperability. In response, this paper presents a new end-to-end workflow for life-cycle assessment (LCA) of buildings that captures the dependencies between multi-hazard resilience and sustainability, across multiple dimensions of environmental impact. An illustrative example reveals how consideration of hazards during design and material selection influence embodied energy, ultimately revealing design choices that best achieve joint resiliency and sustainability

    Modelling and simulation of a stationary high-rise elevator system to predict the dynamic interactions between its components

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    In a high-rise elevator system lateral vibrations of the suspension and compensating ropes, coupled with vertical motions of the car and counterweight are induced by the building structure motions. When the frequency of the building coincides with the fundamental natural frequency of the ropes, large resonance whirling motions of the ropes result. This phenomenon leads to impacts of the ropes on the elevator walls, large displacements of the car and counterweight making the building and elevator system unsafe. This paper presents a comprehensive mathematical model of a high-rise elevator system taking into account the combined lateral stiffness of the roller guides and guide rails. The results and analysis presented in the paper demonstrate frequency curve veering phenomena and a wide range of resonances that occur in the system. A case study is presented when the car is parked at a landing level where the fundamental natural frequencies of the car, suspension and compensating rope system coincide with one of the natural frequencies of the high-rise building. The results show a range of nonlinear dynamic interactions between the components of the elevator system that play a significant role in the operation of the entire installation

    Nonlinear vibrations of a cable system with a tuned mass damper under deterministic and stochastic base excitation

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    This paper investigates a dynamic model of a cable – mass system equipped with an auxiliary mass element to act as a transverse tuned mass damper (TMD). The cable length varies slowly while the system is mounted in a vertical host structure swaying at low frequencies. This results in base excitation acting upon the cable - mass system. The model is represented by a system of nonlinear partial differential equations (PDE) with corresponding boundary conditions defined in a slowly time-variant space domain. The Galerkin method is used to discretise the PDE model. The model takes into account the fact that the longitudinal elastic stretching of the cable is coupled with their transverse motions. The TMD is applied to reduce the dynamic response of the system. The parameters of TMD are selected by the application of a linearized model and a single-mode approximation. In this approach the excitation is represented as a narrow-band Gaussian process mean-square equivalent to a harmonic process. The deterministic model and stochastic model can be used to predict and control the primary resonance response of the system

    Identification of dynamic displacements and modal frequencies of amedium-span suspension bridge using multimode GNSS processing

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    Global Navigation Satellite System (GNSS) positioning technology has been employed in the dynamic monitoring of long-span bridges in the recent years. However, it has difficulties to meet the higher accuracy requirements of the dynamic monitoring of small or medium span bridges, due to the presence of measurement noise from multipath, cycle slips, ionosphere delay, orbital errors, etc. To verify the feasibility of using current GNSS technology to monitor these bridges, a series of monitoring experiments have been carried out on the Wilford suspension bridge in Nottingham (UK) with GNSS and a triaxial accelerometer. Three GNSS data processing modes, i.e. Real-Time Kinematic (RTK), network RTK and Post-Processing Kinematic (PPK), were considered. An innovative multimode adaptive filtering (MAF) that combining adaptive filter with Chebyshev highpass filter was used to identify the dynamic displacements of the bridge from the multimode GNSS data. To validate the GNSS results, the dynamic displacements were also computed from double integration of the accelerometer-measured accelerations. The differences of the displacements between the GNSS and accelerometer results were obtained. The standard deviation and the mean deviation of these differences are less than 1 mm, which is good enough for the monitoring purposes. The modal frequencies of the bridge can be accurately identified from GNSS measurements, and successfully validated by those from the accelerometer data. Using the multimode GNSS data and the proposed the MAF algorithm, with sub-millimeter level accuracy GNSS can be used to monitor the vibration response of small or medium span bridges as well as long-span bridges

    Integrated workflow for evaluating sustainability and resiliency of building systems

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    This study describes the development of a workflow for integrated life-cycle assessment (iLCA) of buildings that is capable of capturing the dependencies between multi-hazard resilience and sustainability using tools native to professional practice. Modules dedicated to hazard characterization, structural response, damage, repair/loss, and environmental impact (embodied and operating energy) are developed using Application Programming Interfaces (APIs) and semantic data perspectives from computer science. A unifying probabilistic framework is utilized to quantify life-cycle performance and a common, versatile, simulation-based approach is adopted for estimation of performance. This approach supports various resilience/sustainability metrics, including monetary losses, downtime, total embodied energy (initial construction and repairs), and operating energy. A case study executed in the Revit environment evaluates the performance of a special reinforced concrete frame located near Los Angeles International Airport (LAX). Two design alternatives are considered to illustrate the impact of design and material decisions, ultimately revealing design choices which best achieve joint resiliency and sustainability.The authors gratefully acknowledge the support of NSF (CMMI-1537652). The first author also recognizes the support of her NSF Graduate Research Fellowship (DGE-1313583) and Deans Fellowship from the University of Notre Dame. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NSF

    Geospatial environments for hurricane risk assessment: Applications to situational awareness and resilience planning in New Jersey

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    Mitigation of losses due to coastal hazards has become an increasingly urgent and challenging problem in light of rising seas and the continued escalation of coastal population density. Unfortunately, stakeholders responsible for assuring the safety of these coastal communities are not equipped with the engineering research community’s latest tools for high-fidelity risk assessment and geospatial decision support. In the event of a hurricane or nor’easter, such capabilities are exceptionally vital to project storm impacts on critical infrastructure and other municipal assets and to inform preemptive actions that can save lives and mitigate property damage. In response, a web-based visualization environment was developed using the GeoNode content management system, informed by the needs of municipal stakeholders. Within this secure platform, registered users with roles in planning, emergency management and first response can simulate the impact of hurricanes and nor’easters using the platform’s storm Hazard Projection (SHP) Tool. The SHP Tool integrates fast-to-compute windfield models with surrogate models of high-fidelity storm surge and waves to rapidly simulate user-defined storm scenarios, considering the effects of tides, sea level rise, dune breaches and track uncertainty. In the case of a landfalling hurricane, SHP tool outputs are automatically loaded into the user’s dashboard to visualize the projected wind, storm surge and wave run-up based on the latest track information published by the National Hurricane Center. Under either use case, outputs of the SHP Tool are visualized within a robust collaborative geospatial environment supporting the seamless exploration of centralized libraries of geographic information system (GIS) data from federal, state, county and local authorities, with tools to add user-supplied annotations such as notes or other geospatial mark-ups. This paper will overview the development and deployment of this platform in the State of New Jersey, detailing the cyberinfrastructure design and underlying computational models, as well as the user stories that inspired the platform’s functionalities and interfaces. The study concludes with reflections from the process of piloting this project with stakeholders at the state and municipal level to support more risk-responsive and data-informed decision making
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