Instrumented Building Research Articles

No Joy in the Brilliance of Sunshine

Sean Bell Student number: 3230643 Master Early Music Voice Research supervisor: Dr. Inês de Avena Braga Title: No Joy in the Brilliance of Sunshine Research question: How can I create a stage performance combining and connecting my two sound worlds/style identities as a performer? Summary of the results of the research: In this research I have explored the creative development of a stage performance, combining operatic music by Handel with contemporary performance art. Through this I have explored how I can combine my duality as a performer: the early music singer and the contemporary performer and creator. This project and its connected research are a part of my artistic development as a musician, creator and performer, and the urge to explore this music and questions grew out of previous projects and ideas. I have created and developed my project through following a consequential progression of artistic choices, and through this space that has unfolded I have come to find an essential identity of myself as a performer and creator. By being honest towards myself through the critical reflection, I have been able to investigate my process, my preferences, inspirations and my distinct personal style. Through this I have been able to strengthen my artistic identity and the artistic tools I use, bringing forth a more complete performer. Short biography: Sean Bell is a countertenor and performance artist from Oslo. His studies centre mainly on chamber and sacred music and opera, yet also includes a focus on new ideas and methods of interpreting classical and contemporary repertoire. Through sonic imaginations and arrangements, he explores this repertoire in new ways. This has led him to a series of collaborations and solo performances on the border line between classical music and performance art. Bell also works with contemporary music and has premiered several pieces for countertenor. He is an active improviser, plays baroque guitar and engages in instrument building and music electronics.

Demands on acceleration-sensitive nonstructural components in special concentrically braced frame and special moment frame buildings

This study investigates demands on acceleration-sensitive nonstructural components (NSCs) in code-compliant Special Concentrically Braced Frame (SCBF) and Special Moment Frame (SMF) structures. Previous studies have highlighted that the assumption of ASCE 7-16 for the ratio of Peak Floor Acceleration (PFA) to Peak Ground Acceleration (PGA) is overly conservative. In most previous studies, the results were based on generic analytical models with non-deteriorating structural behavior or recorded data from instrumented buildings subjected to ground motions that were significantly weaker than the design-level earthquakes. This study evaluates the acceleration demands on NSCs in 11 archetype buildings modeled using advanced techniques. The ground motions used elicit inelastic response in the frames at the level expected by ASCE 7-16 compliant designs. The study examines the effect of the ratio of NSC period to structural period, NSC damping ratio, and NSC vertical location on these demands. Results of this investigation are compared with the provisions of ASCE 7-16 and the recommendations of the recently completed effort by the Applied Technology Council 120 project (ATC-120), which are the basis for the seismic design requirements for nonstructural components in the forthcoming ASCE 7-22 standard. Equations for the PFA/PGA ratio and NSC amplification factor, which account for the dynamic characteristics of the buildings, are developed based on regression analysis of the generated data. Results of the analyses indicate that the formula recommended by ATC-120 for estimating PFA/PGA along the height of the structure, which includes building nonlinearity effects through a constant building ductility reduction factor, overestimates floor accelerations at the top floors but underestimates them in the lower floors of the archetypes considered. At the same time, results show that the NSC seismic design force equation recommended by ATC-120 is conservative for the SCBF archetypes, while it underestimates the NSC force demands in the SMFs.

A computationally efficient framework for the simulation of the nonlinear seismic performance of infilled RC frame buildings

This study proposes a novel approach for the computationally efficient numerical modeling of the nonlinear seismic response of entire buildings with infilled RC frames. The proposed modeling framework can be particularly helpful for buildings with multiple stories and complex layouts, for which the current methods can be cumbersome to implement, or inaccurate. This framework combines the force-vs.-displacement response for every bay of the building to obtain the envelop curves for every floor along the two main perpendicular horizontal directions. These curves are used to calibrate a box-type model of the building. The proposed methodology is employed to simulate the response of a two-bay, three-story frame tested on a shake table, and an instrumented four-story school building in Nepal, damaged by the 2015 Gorkha earthquake. The comparison of the numerical results with the test and field data indicates that the proposed approach can accurately capture the important features of the seismic response of the actual structures and their dynamic properties.

Earthquake Early Warning for Estimating Floor Shaking Levels of Tall Buildings

ABSTRACTThis article investigates methods to improve earthquake early warning (EEW) predictions of shaking levels for residents of tall buildings. In the current U.S. Geological Survey ShakeAlert EEW system, regions far from an epicenter will not receive alerts due to low predicted ground-shaking intensities. However, residents of tall buildings in those areas may still experience significant shaking due to the acceleration amplification caused by tall buildings’ dynamic behavior, as recently experienced by residents of the 52-story building in downtown Los Angeles (DTLA) during the 2019 M 7.1 Ridgecrest earthquake. Using more than 400 recorded response data acquired from 77 instrumented buildings in California, here we compare the Federal Emergency Management Agency (FEMA) P-58 and American Society of Civil Engineers (ASCE) 7-16 simplified equations for peak floor acceleration (PFA), finding that the ASCE estimation is close to the median of data recorded in large and long-distance events, whereas the current FEMA estimation is not suitable. In the second part of this article, four instrumented tall buildings in DTLA are extensively studied, and the performance of the simplified and response spectrum (RS) methods giving both an estimation of the free-field horizontal peak ground acceleration (PGA) and pseudospectral acceleration is evaluated. The results show that the RS method is as accurate as the response history analysis as long as the ground-motion RS is accurate, whereas the ASCE 7-16 prediction is conservative. However, when ground-motion RS or PGA is estimated for DTLA using a ground-motion model (GMM), the performance of the RS method significantly degrades due to underestimation by the GMM at long periods. The results of this study imply that a nonergodic GMM, which may give more accurate prediction in Los Angeles, could improve the results for PFA when the building’s behavior is dominated by a few long-period fundamental modes, as is the case for the 52-story building in DTLA.

"Fabrica" and "Ratiocinatio". Introductory Notes on Design and Semiotics

Although Vitruvius’ De architectura libri decem is generally regarded as the most ancient remaining piece of some sort of architectural theory, it is better to think of it as a book devoted to ancient design culture mutatis mutandis. We can do this retrofitting or intended retrospective anachronism with good conscience since a book on architectura written more than two thousand years ago can hardly be described as an example of the theory of architecture, since the concept did not exist at the time. A quick look at Vitruvius’ masterpiece brings to attention, for example, that its tenth book is on architectura organica, which has naturally nothing to do with the mod-ern style and phenomena of organic architecture, but with the design and building of machines, tools, and instruments (that is, organa). Etymologically speaking, architectus (or its Greek equivalent, architektōn) means someone who designs and creates the principal structures of any designed environment. In order to do so, one applies fabrica and ratiocinatio at the very same time. On the one hand, therefore, the architectus is well versed in craf ting basic structures, but he is equally capable of inventing, imagining, or designing these environments, objects, tools, and instruments, as well as clearly explaining and instructively interpreting their structure and executing process. Hence, according to Vitruvius, a designer who strives only to manual prac-tice without written culture (sine litteris) cannot be successful at all.

Vibration characteristics and isolation in vibration-sensitive areas under moving vehicle load

A precision instrument building is used to house various experimental equipments that are sensitive to ground vibrations. In order to research the characteristics of ground vibrations under the moving vehicle load, a field test of vibration was carried out. A coupling model of moving vehicle load-foundation soil-building structure was established to simulate vibration isolation measures and analyze the vibration isolation effect. The results indicate that the ground vibrations in the sensitive area caused by the moving vehicle load are mainly low frequency in the vertical direction, where the principal frequency is in the 3∼4 Hz range, consistent with the ground pulsation test. The horizontal vibration attenuates much faster than the vertical vibration. For the vibration isolation using the piles, factors including pile spacing, pile length and barrier width have a significant impact on the vibration isolation effect, while the number of pile rows and the material of piles have relatively little influence. Using the optimized vibration isolation plan, the vibration in the sensitive area caused by the moving vehicle load can be reduced by about 30∼50%. The research methods and conclusions of this paper can serve as a useful reference for the analysis of ground vibrations and vibration isolation design in vibration-sensitive areas.

Real-world application of hysteresis loop analysis for stiffness identification of an instrumented building across multiple seismic events

The BNZ building in Wellington, New Zealand was significantly damaged, and eventually demolished, due to the cumulative impact of three main earthquakes between 2013 and 2016. Although the building was equipped with a set of accelerometers, lack of an accurate SHM method allowed the damage level to remain hidden to engineers and property owners. An accurate SHM method would have quantified the seriousness of the damage in this building over each of three major events, enabling proper retrofit and better decision making.This study uses the hysteresis loop analysis (HLA) SHM method to investigate lateral stiffness changes for this structure, and the trajectory of damage accumulation for each story over all three events. HLA indicates the building suffered average stiffness reductions of 24%, 21% and 9% due to each event in the x direction, respectively, and 34%, 3% and 16% in the y direction. The first story lost ∼65% of its initial stiffness by the end of the third event. Between event differences or consistency, over all six stories, all events, and both directions, is ∼5% on average, providing an accurate, continuous SHM trajectory.HLA shows very good robustness and consistency in estimating elastic stiffness changes due to damage in this real-world, full-scale case analysis. Consistent, accurate estimation can help optimize decisions after major events. They also offer the future potential to build a virtual building model accurately predict forward what might happen to an already damaged structure in future events.

Identifying Dynamic Response of a Twenty-Story Instrumented Building to 2018 M7.1 Anchorage, Alaska Earthquake and Its Aftershocks

ABSTRACT The dynamic responses of an instrumented twenty-story steel-moment frame office building were identified with the data from mainshock (M 7.1) occurred on November 30, 2018 and its six aftershocks ranging from M4.2 to 5.7 in the Alaska-Aleutian subduction zone. The deconvolution-based seismic interferometry was used to identify the traveling waves and intrinsic-damping ratio in the building. The median shear-wave velocity is 179 m/s for the east-west (EW), 201 m/s for the north-south (NS), and 174 m/s for the torsional responses. The building’s average intrinsic-damping ratio is estimated to be 4.4% and 3.7% for the EW and NS directions, respectively.

Formation of holographic diffraction gratings in thin films of chalcogenide glassy semiconductors

The paper presents a study of the formation of holographic diffraction gratings in thin films of chalcogenide glassy semiconductors. The recording process of holographic gratings at the argon-laser radiation wave length 488 nm and the process of chemical etching that enables the formation of а relief holographic grating are analysed. The optimum conditions for the formation of diffraction gratings in films of arsenic sulfide As2S3 are defined. It is shown that at the 488 nm wave length of an argon laser the optimum exposure comes to ∼5–8 J/cm2. At the recording stage a quasi-phase (relief-phase) grating is formed, with the diffraction efficiency on the order of a few per cent. Etching of the exposed sample with a solution of NaOH alkali in deionised water and isopropanol makes it possible to increase considerably the relief depth and to improve the diffraction efficiency of a thin diffraction grating approximately up to 20 % for the red spectral region, and to approach the maximal value ∼34 % for the near infra-red region. The results of the study considered look promising for the creation of relief holographic gratings which are essential in present-day optical instrument building (production of spectral devices, holographic sights, and the like).

Bayesian Joint State-Parameter-Input Estimation of Flexible-Base Buildings from Sparse Measurements Using Timoshenko Beam Models

This paper presents a computationally efficient framework for the Bayesian identification of sparsely instrumented building structures that is amenable to rapid postearthquake condition assessment. Flexible-base Timoshenko beam models are employed within a Bayesian framework, which uses the extended Kalman filter (EKF) as a joint state-parameter-input estimation tool. Highly sparse and noisy measurements are utilized to identify the properties of the superstructure, the soil–foundation substructure, and the foundation input motion simultaneously under strong nonstationary shaking. The proposed framework is verified and its robustness is examined through synthetic problems featuring wide-ranging random initial errors. A validation study is also carried out on an instrumented building, namely, Caltech’s Millikan Library. The results show that the proposed framework is capable of estimating the unknown parameters of the soil-foundation-structure system together with the input excitation using as few as three measurement channels. Representing the superstructure by a model that offers an analytical solution to system dynamics and determining the analytical derivatives for EKF using direct differentiation has led to a computationally efficient and accurate tool that robustly identifies the system from a minimal set of measurements.

Evaluation of the Floor Acceleration Amplification Demand of Instrumented Buildings

The floor acceleration amplification (FAA) factor is one of the most critical parameters in computing the equivalent seismic force of nonstructural component (NC). To evaluate the heightwise FAA distribution profile, the recorded acceleration response of the instrumented buildings was analyzed using the California Strong Motion Instrumentation Program (CSMIP) database. The FAA demands for three groups of buildings consisting of reinforced concrete, steel, and masonry buildings were analyzed. In each group, the buildings were classified into four subgroups according to their heights. Parabolic distribution profiles were suggested that could envelop most of the FAA data, as demonstrated by the processed results. An earthquake experience-based importance factor was suggested in terms of the percentage of the enveloped records. The obtained FAAs at the roof were generally larger than those in other levels. The percentile distributions of the roof acceleration amplification (RAA) were computed. The results showed that the roof FAA was underestimated in ASCE 7-16. The magnitudes of the FAA and the RAA correlated to the fundamental period of the building, which was considered by classifying the buildings according to the period ranges. The RAA profile against the period was obtained from a regression analysis. The developed FAA profile is expected to be useful in the seismic design of NCs, and it is expected to be adopted in future code provisions.

Evaluation of the Floor Acceleration Response Spectra of Numerical Building Models Based on Recorded Building Response Data

ABSTRACT The recorded floor acceleration responses of a wide variety of instrumented buildings are used to evaluate the findings of previous numerical studies regarding the effect of different parameters on the seismic response of nonstructural components (NSCs). These relevant parameters include, but are not limited to, the lateral force resisting system, modal periods, and inelastic behavior of supporting building; the intensity and frequency content of ground excitation; damping ratio, tuning condition, and location of NSCs. The data from instrumented buildings are also used to validate relationships proposed by the first two authors for the estimation of NSC damping modification factor.

Structural Health Monitoring Using Machine Learning and Cumulative Absolute Velocity Features

Machine learning (ML)-aided structural health monitoring (SHM) can rapidly evaluate the safety and integrity of the aging infrastructure following an earthquake. The conventional damage features used in ML-based SHM methodologies face the curse of dimensionality. This paper introduces low dimensional, namely, cumulative absolute velocity (CAV)-based features, to enable the use of ML for rapid damage assessment. A computer experiment is performed to identify the appropriate features and the ML algorithm using data from a simulated single-degree-of-freedom system. A comparative analysis of five ML models (logistic regression (LR), ordinal logistic regression (OLR), artificial neural networks with 10 and 100 neurons (ANN10 and ANN100), and support vector machines (SVM)) is performed. Two test sets were used where Set-1 originated from the same distribution as the training set and Set-2 came from a different distribution. The results showed that the combination of the CAV and the relative CAV with respect to the linear response, i.e., RCAV, performed the best among the different feature combinations. Among the ML models, OLR showed good generalization capabilities when compared to SVM and ANN models. Subsequently, OLR is successfully applied to assess the damage of two numerical multi-degree of freedom (MDOF) models and an instrumented building with CAV and RCAV as features. For the MDOF models, the damage state was identified with accuracy ranging from 84% to 97% and the damage location was identified with accuracy ranging from 93% to 97.5%. The features and the OLR models successfully captured the damage information for the instrumented structure as well. The proposed methodology is capable of ensuring rapid decision-making and improving community resiliency.

Evaluation of Pinching Effects on a Real Concrete Building Seismic Performance by Resimulating Displacement Responses Using HLA SHM Results

Assessment of structural damage state immediately after earthquakes can play an important role in decreasing economic and life losses, and in optimizing decision-making for affected buildings. These advantages highlight the need for rapid, accurate, and automated structural health monitoring (SHM) methods, as well as the need for generalizable model development methods to accurately resimulate nonlinear response to find the root causes of structural damage and identify elements for retrofit. This study tracked lateral stiffness changes for a real instrumented RC building subjected to three damaging earthquakes between 2013 and 2016 using the proven hysteresis loop analysis (HLA) SHM method. An idealized trilinear force–deformation pinching model created from HLA results is proposed to resimulate highly nonlinear pinching behavior of the building under these events. The proposed model facilitates assessment of the pinching region and its characteristics in terms of seismic response, stiffness and strength degradation, and the overall seismic performance of this RC building. Average correlation coefficients between measured and resimulated interstory displacement were 0.90, 0.97, and 0.97 across all stories for the three events, respectively. Resimulated interstory displacement error was less than 4% on average over all stories and events. These good resimulation results further validated the HLA method. More importantly, the proposed model clearly showed how pinching region length and its participation in dissipating energy increases as cumulative earthquake-induced damage increases in the building, potentially helping hide significant damage from typical detection methods. Thus, in addition to presenting a generalizable nonlinear modeling approach for postevent structural assessment, the overall results bring attention to the significant role that pinching plays in seismic energy dissipation and response for RC buildings.

Numerical Study of the Seismic Response of an Instrumented Building with Underground Stories

Engineering practitioners do not usually include soil-structure interactions in building design; rather, it is common to model and design foundations as embedded joints with joint–based reactions. In some cases, foundation structures are modeled as rigid bodies, embedding the first story into lower vertical elements. Given that the effects of underground floors on the seismic response are not generally included in current building design provisions, it has been little explored in the literature. This work compares and analyzes models to study the effects of different underground stories modeling approaches using earthquake vibration data recorded for the 16–story Alcazar building office in downtown Viña del Mar (Chile). The modeling expands beyond an embedded first story structure to soil with equivalent springs, representing soil-structure interaction (SSI), with varying rigid soil homogeneity. The building was modeled in a finite element software considering only dead load as a static load case because the structure remained in the framing stage when the monitoring system was operating. The instruments registered 72 aftershocks from the 2010 Maule Earthquake, and this study focused on 11 aftershocks of different hypocenters and magnitudes to collect representative information. The comparisons between empirical records and models in this study showed a better fit between the model and the real vibration data for the models that do consider the SSI using horizontal springs attached to the retaining walls of the underground stories. In addition, it was observed that applying a stiffness reduction factor of 0.7 to all elements in deformation verification models for average-height buildings was suitable to analyze the behavior under small earthquakes; better results are obtained embedding the structure in the foundation level than embedding in the street level; the use of horizontal springs with Kuesel’s model with traction for the analysis of the structure yields appropriate results; it is necessary to carefully select the spring constants to be used, paying special attention to the vertical springs. Even though the results presented herein indicate that the use of vertical springs to simulate the SSI of the base slab can result in major differences concerning the real response, it is necessary to obtain more data from instrumentation across a wider variety of structures to continue to evaluate better design and modeling practices. Similarly, further analyses, including nonlinear time-history and high-intensity events, are needed to best regulate building design.

Human-machine collaboration framework for structural health monitoring and resiliency

Post-earthquake damage assessment can be significantly expedited when machine learning (ML) algorithms supported by sensing technologies are used. ML has some limitations when it comes to seismic damage assessment. ML tools require data from each class while training but in the case of seismic structural health monitoring, vibration data are usually available from the undamaged structures. In this paper, a framework called the human-machine collaboration (H-MC) is proposed. The H-MC framework combines the ML tools and human (domain) expertise for damage assessment of real instrumented buildings with only data from undamaged cases. It uses novelty detection as the ML tool and structure-specific analytical model to enable rapid damage detection. Subsequently, the framework is applied to detect damage in real instrumented buildings. The results showed that the H-MC algorithm correctly detected the damaged cases. It also labeled all the undamaged events accurately eliminating false positive detection. Furthermore, it is revealed that the resiliency of a building can be improved when the H-MC method is implemented over traditional field inspection. The proposed framework can be a viable tool for rapid post-earthquake damage assessment which is essential for improving community resiliency.

Virtual metering of heat supplied by zone-level perimeter heaters: An investigation with three inverse modelling approaches

Virtual metering at the equipment level provides a non-intrusive tool to understand energy flows in commercial buildings and monitor building energy performance. The accuracy of virtual meters depends on the modelling approach and its ability to capture the underlying physical processes. This paper presents a novel comparison and provides guidance for the selection of inverse modelling approaches used to create virtual meters to estimate the heat supplied by zone-level hydronic perimeter heaters. The approaches investigated are: steady-state inverse greybox modelling, transient inverse greybox modelling, and water-side load disaggregation. Models that represent these three approaches are trained using data from a highly instrumented academic building in Ottawa, Canada. Model parameters are identified using the genetic algorithm and used in creating virtual meters that can estimate the heat added by perimeter heaters into building variable air volume zones. The accuracy of these virtual meters is assessed by comparing them to physical meters installed in these zones. The results indicate that the three modelling approaches can estimate the daily heating energy supplied by perimeter heaters at a normalized root-mean-square error between 16% and 18%. However, the accuracy of the virtual meters declines as the number of zones increases. The performance of the three modelling approaches is evaluated through illustrative examples that compare modelling assumptions, data requirements, data processing, and model prediction accuracy.

Forecasts on the seismic behavior of buildings constructed with the Great Soviet Panel

After a visual inspection of a representative sample of 200 buildings, pathological deterioration in structural elements and joints, with severe levels of damage, was detected in the buildings built with the Great Soviet Panel prefabricated system in Santiago de Cuba. Likewise, increases in weight and changes in rigidity were found, due to the contraventions of the inhabitants. In this research, with the aim of forecasting the seismic behavior of some buildings built with the Great Soviet Panel precast system, the values of the fundamental periods are determined through the environmental vibrations of 7 buildings that make up the sample studied. It is concluded that changes are expected in the seismic behavior of these instrumented buildings.

Temperature measurement assisted modal tracking of an instrumented building

In Structural Health Monitoring (SHM), the instrumentation policies for buildings usually require large numbers of high-resolution sensors. The relatively high economic cost for the sensors and their interconnecting cables has discouraged the widespread application of SHM. For modal analysis, small number of sensors means low spatial resolution of mode shapes, which limits the possibility of differentiating between close frequency modes in a single measurement and between consecutive measurements on a continuous monitoring system. In this study, we try to overcome this limitation, particularly on the tracking component of SHM, with the aid of a predictive numerical model based on the effect of the ambient temperature on the modal frequency. To validate this hypothesis, we test it on a real building, monitored with a small number of low-resolution sensors. The methodology’s performance is evaluated during normal conditions, rainfall and also after the damaging Chile Maule earthquake (Mw of 8.8), proving to be effective for tracking purposes. For this building, the sensitivity of the mode shape and damping to the environment is also studied, showing a very low sensitivity as compared to the frequency. This validates the simpler temperature – frequency model.

Evaluation of floor acceleration demands from the 2017 Mexico City code seismic provisions using a continuous elastic model and records of instrumented buildings

This study presents an evaluation of floor acceleration demands for the design of rigid and flexible acceleration-sensitive nonstructural components in buildings, calculated using the most recent Mexico City seismic design provisions, released in 2017. This evaluation includes two approaches: (1) a simplified continuous elastic model and (2) using recordings from 10 instrumented buildings located in Mexico City. The study found that peak floor elastic acceleration demands imposed on rigid nonstructural components into buildings situated in Mexico City might reach values of 4.8 and 6.4 times the peak ground acceleration at rock and soft sites, respectively. The peak elastic acceleration demands imposed on flexible nonstructural components in all floors, estimated using floor response spectra, might be four times larger than the maximum acceleration of the floor at the point of support of the component for buildings located in rock and soft soil. Comparison of results from the two approaches with the current seismic design provisions revealed that the peak acceleration demands and floor response spectra computed with the current 2017 Mexico City seismic design provisions are, in general, adequate.