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, has yet to be systematically validated in full scale. In response to this need, through the combined efforts of members of academe, a design firm and a commercial wind tunnel testing laboratory, a program was initiated to monitor the full-scale response of representative tall buildings and compare this to the predicted response from wind tunnels and finite-element models used commonly in design. As part of this monitoring program, in situ periods and damping ratios over a range of response amplitudes are also being evaluated. This paper provides an overview of the monitoring program, which includes three tall buildings in the city of Chicago, details their instrumentation and modeling, and provides an example of the full-scale response data analyses being conducted.

This 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...

Two independently emerging time-frequency transformations in Civil Engineering, namely, the wavelet transform and empirical mode decomposition with Hilbert transform (EMD+HT) , are discussed in this study. Their application to a variety of nonstationary and nonlinear signals has achieved mixed results, with some comparative studies casting significant doubt on the wavelet’s suitability for such analyses. Therefore, this study shall revisit a number of applications of EMD+HT in the published literature, offering a different perspective to these commentaries and highlighting situations where the two approaches perform comparably and others where one offers an advantage. As this study demonstrates, much of the differing performance previously observed is attributable to EMD+HT representing nonlinear characteristics solely through the instantaneous frequency, with the wavelet relying on both this measure and the instantaneous bandwidth. Further, the resolutions utilized by the two approaches present a seconda...

The Civil Engineering community has long needed methods of accurate global displacement measurement for use in construction and more recently in the areas of structural health monitoring. Global Positioning Systems (GPS) provide one answer to this challenge, with rapid advancements in the available sampling rates and tracking resolution. However, as a relatively new dynamic sensing technology, GPS performance must be thoroughly validated before its application in full scale. This paper details an experimental program with this aim, documenting the performance of a high-precision GPS in terms of its background noise and dynamic tracking ability, while providing position quality thresholds suitable for qualifying the accuracy of tracking in full scale. Given the performance observed in these studies, considerations for full-scale deployment are offered as well as an assessment of its efficacy in monitoring the dynamic motions of a tall building through the Chicago full-scale monitoring project.

The wind‐induced response of tall buildings is inherently sensitive to structural dynamic properties like frequency and damping ratio. The latter parameter in particular is fraught with uncertainty in the design stage and may result in a built structure whose acceleration levels exceed design predictions. This reality has motivated the need to monitor tall buildings in full‐scale. This paper chronicles the authors' experiences in the analysis of full‐scale dynamic response data from tall buildings around the world, including full‐scale datasets from high rises in Boston, Chicago, and Seoul. In particular, this study focuses on the effects of coupling, beat phenomenon, amplitude dependence, and structural system type on dynamic properties, as well as correlating observed periods of vibration against finite element predictions. The findings suggest the need for time–frequency analyses to identify coalescing modes and the mechanisms spurring them. The study also highlighted the effect of this phenomenon on damping values, the overestimates that can result due to amplitude dependence, as well as the comparatively larger degree of energy dissipation experienced by buildings dominated by frame action. Copyright © 2007 John Wiley & Sons, Ltd.

The NatHaz Aerodynamic Loads Database (NALD) (http://aerodata.ce.nd.edu) introduced in 2000 has served an important first step in establishing an on-line experimental archive of high-frequency base balance (HFBB) data for use in the preliminary design of high-rise buildings subjected to wind loads. As a result, NALD was recently introduced in the Commentary of ASCE 7-05 (C6.5.8) as an alternative means of assessing the dynamic wind load effects on high-rise buildings. This paper presents NALD version 2.0 (v. 2.0), integrating the latest advances in data management and mining for interactive queries of aerodynamic load data and an integrated on-line analysis framework for determining the resulting base moments, displacements, and equivalent static wind loads for survivability and accelerations for serviceability (habitability). The key feature of NALD v. 2.0 is the flexibility its analysis module offers: Users may select not only the data from the on-line NatHaz aerodynamic loads database, but also may inp...