Tracy Kijewski-Correa

Structural identification of constructed systems : approaches, methods, and technologies for effective practice of St-Id

Structural Identification of Constructed Systems: Approaches, Methods, and Technologies for Effective Practice of St-Id offers an overview of nearly 20 years of research directed at bridging the gap in structural engineering between models and real structural systems. Structural identification, known as St-Id, can be defined as the process of creating and updating a model of a structure (for instance, a finite element model) using experimental observations and data. By developing reliable estimates of the performance and vulnerability of structural systems, St-Id produces improved simulations that, in turn, assist in decision making and the transition to performance-based civil engineering. Drawing upon contributions from experts in the field, this report focuses on defining the most critical considerations of St-Id, which include: modelling, both analytical and numerical experimentation, including observations, sensing, and monitoring data processing, including error screening and feature extraction model calibration, including comparisons of models and experimental data, model updating, and model selection decision support, such as scenario analyses and risk assessment Two appendixes present case studies demonstrating the St-Id of buildings and of bridges. Structural engineers, educators, and researchers working in the areas of structural modelling, health monitoring, assessment, forensics, performance evaluation, predictive analysis, and decision making will find this book useful in covering critical and practical aspects of these concepts.

SmartSync: An Integrated Real-Time Structural Health Monitoring and Structural Identification System for Tall Buildings

AbstractThis study introduces a unique prototype system for structural health monitoring (SHM), SmartSync, which uses the building’s existing Internet backbone as a system of virtual instrumentation cables to permit modular and largely plug-and-play deployments. Within this framework, data streams from distributed heterogeneous sensors are pushed through network interfaces in real time and seamlessly synchronized and aggregated by a centralized server, which performs basic data acquisition, event triggering, and database management while also providing an interface for data visualization and analysis that can be securely accessed. The system enables a scalable approach to monitoring tall and complex structures that can readily interface a variety of sensors and data formats (analog and digital) and can even accommodate variable sampling rates. This study overviews the SmartSync system, its installation/operation in the world’s tallest building, Burj Khalifa, and proof-of-concept in triggering under dual e...

Full-Scale Validation of Wind-Induced Response of Tall Buildings: Investigation of Amplitude-Dependent Dynamic Properties

This study investigates the effect of amplitude-dependence on the dynamic properties of a 865 ft (264 m) tall residential building. The amplitude-dependent features of this building are investigated using a time domain approach and are compared to existing models in the literature. In particular, this study highlights the impact of amplitude-dependent frequency on damping estimates by traditional spectral methods.

Structural Identification of Constructed Systems: Collective Effort toward an Integrated Approach That Reduces Barriers to Adoption

Structural identification (St-Id) is a powerful tool that bridges the gap between constructed systems and themodels used in their design and assessment. Although St-Id has attracted the attention of numerous researchers worldwide over the last several decades, it unfortunately has not experienced widespread adoption in practice. The ASCE Structural Engineering Institute Structural Identification of Constructed Systems Committee is seeking to reverse this trend by enhancing advocacy toward and promoting implementation of St-Id within the public and private sectors. The committee’s first action on this front was the development of a comprehensive report that benchmarks the current state of the art in St-Id, with special attention to case studies of its successful implementation. To organize the diverse paradigm of St-Id, the committee adopted a six-step cycle that spansmodeling through experimentation and ultimately to decision support. This forum paper overviews the report with the first six chapters dedicated to this cycle, as well as the report’s closing two chapters dedicated to case studies that exemplify the implementation of St-Id to various buildings and bridges around the world.

The Haitian housing dilemma: can sustainability and hazard-resilience be achieved?

The present danger in the Haitian rebuilding efforts, outside of the extreme level of need that often encourages temporary solutions at the expense of long-term capacity building, centers on the assumption that sustainability and resilience are mutually exclusive. They cannot be if this rare opportunity to achieve meaningful long-term change within a country that has suffered for far too long is to be fully seized. This change can be realized only with appropriate policies and incentives that do not simply fund the re-implementation of vulnerable construction modes in an effort to meet immediate needs, but that foster the introduction of alternative structural systems with the requirement that they build genuine local capacity to deliver sustainable and resilient homes that meet Haiti’s cultural and economic constraints. This short communication reviews the important housing dilemma Haiti now faces, a dilemma with international extensions since researchers and construction firms from all over the world (including France, Germany, Italy, Greece, Japan, Canada, US) are involved, and presents thoughts for the importance of offering solutions that serve both ends of the economic spectrum, are hazard-resilient and truly sustainable.

Assessment of Residential Housing in Léogâne, Haiti, and Identification of Needs for Rebuilding after the January 2010 Earthquake

Two months after the 2010 Haiti Earthquake, a reconnaissance team from the University of Notre Dame traveled to Léogâne with a follow up trip in August 2010. The team sought to determine the failure modes for residential housing in the area and survey the structural systems, construction materials, building practices, and non-engineering constraints that dictate these practices. The failure modes observed were commonly initiated from undersized/under-reinforced columns, though even structures with adequately sized columns sustained significant damage due to shear forces transferred by stiff but brittle unreinforced masonry walls. Inadequate seismic detailing of reinforced concrete elements, deficient materials and construction practices, and lack of seismic considerations in the design of structural systems with sufficient lateral interconnectivity were also observed. Finally, strategies now being pursued by the authors will be showcased in an effort to develop multihazard-resilient housing that can be sustained locally.

Predictive Models for Damping in Buildings: The Role of Structural System Characteristics

Damping is dependent on many variables and complex mechanisms that are not yet fully quantifiable in the design stage. This has led to generic assignments of viscous damping usually based on material type and at best based on height with reference to existing databases. This study will employ recent full-scale observations to demonstrate the role of the structural system’s dominant deformation mechanism frame racking vs. cantilever action – in energy dissipation capability. Specifically, it is shown that frame racking and other shear deformations dissipate more energy than the axial shortening associated with cantilever action. As such, the ratio of frame racking to cantilever action may offer a more robust and intuitive parameter better suited for use in predictive viscous damping models. This study serves as the first step in the development of such models, with a specific focus on serviceability design.

Full-Scale Validation of the Wind-Induced Response of Tall Buildings: Updated Findings from the Chicago Monitoring Project

While high-rise construction serves as one of the most challenging projects undertaken by society each year, tall buildings are one of the few constructed facilities whose design relies solely upon analytical and scaled models, which, though based upon fundamental mechanics and years of research and experience, have yet to be systematically validated in full-scale. In response to this deficiency, a full-scale monitoring project was initiated through the combined efforts of members of academe (University of Notre Dame), practicing design firms (Skidmore, Owings & Merrill LLP, Chicago) and commercial testing laboratories (Boundary Layer Wind Tunnel Laboratory, University of Western Ontario, Canada). The objective of this program is to monitor the full-scale response of some representative tall building structures and compare their actual performance to the predictions from wind tunnel testing and finite element computer models used in their design. As such, this program offers the opportunity to refine the design state-of-the-art based on any discrepancies revealed. As part of this full-scale evaluation, in-situ periods and damping ratios over a range of response amplitudes are being ascertained, which will prove vital for expanding the existing databases of full-scale dynamic properties. This paper presents a brief overview of the program.

GPS monitoring in urban zones: calibration and quantification of multipath effects

Health monitoring is becoming an increasingly valuable tool for assessment of aging infrastructure in urban zones. For such applications, Global Positioning Systems (GPS) present a promising monitoring technique-one that is able to capture the total displacements of a structure. However, due to the relative infancy of this technology, there are still issues to be resolved, including the characterization and removal of multipath effects. This paper discusses the manifestation and removal of multipath errors by examining the full-scale response of a tall building to demonstrate the accuracy of high precision GPS in comparison with traditional sensors like accelerometers.

Lessons Learned from Crowdsourcing Complex Engineering Tasks

Crowdsourcing Crowdsourcing is the practice of obtaining needed ideas, services, or content by requesting contributions from a large group of people. Amazon Mechanical Turk is a web marketplace for crowdsourcing microtasks, such as answering surveys and image tagging. We explored the limits of crowdsourcing by using Mechanical Turk for a more complicated task: analysis and creation of wind simulations. Harnessing Crowdworkers for Engineering Our investigation examined the feasibility of using crowdsourcing for complex, highly technical tasks. This was done to determine if the benefits of crowdsourcing could be harnessed to accurately and effectively contribute to solving complex real world engineering problems. Of course, untrained crowds cannot be used as a mere substitute for trained expertise. Rather, we sought to understand how crowd workers can be used as a large pool of labor for a preliminary analysis of complex data. Virtual Wind Tunnel We compared the skill of the anonymous crowd workers from Amazon Mechanical Turk with that of civil engineering graduate students, making a first pass at analyzing wind simulation data. For the first phase, we posted analysis questions to Amazon crowd workers and to two groups of civil engineering graduate students. A second phase of our experiment instructed crowd workers and students to create simulations on our Virtual Wind Tunnel website to solve a more complex task. Conclusions With a sufficiently comprehensive tutorial and compensation similar to typical crowd-sourcing wages, we were able to enlist crowd workers to effectively complete longer, more complex tasks with competence comparable to that of graduate students with more comprehensive, expert-level knowledge. Furthermore, more complex tasks require increased communication with the workers. As tasks become more complex, the employment relationship begins to become more akin to outsourcing than crowdsourcing. Through this investigation, we were able to stretch and explore the limits of crowdsourcing as a tool for solving complex problems.