Field Testing Capabilities of the NEES@UCLA Equipment Site for Soil-Structure Interaction Applications

Stewart, Jonathan P.; Whang, Daniel H.; Wallace, John W.; Nigbor, Robert L.

doi:10.1061/40779(158)2

Cited by 8 publications

(3 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Only a few of the past studies have employed real‐life seismic data to quantify the dynamic soil‐foundation stiffness . Most pertinent to the present effort, Ghahari et al proposed an identification methodology based on a deterministic model updating technique for estimating the dynamic stiffness from strong motion records.…”

Section: Introductionmentioning

confidence: 99%

Bayesian identification of soil-foundation stiffness of building structures

Shirzad-Ghaleroudkhani

Mahsuli

Ghahari

et al. 2017

Struct Control Health Monit

View full text Add to dashboard Cite

Summary A probabilistic method is presented for identifying the dynamic soil‐foundation stiffnesses of building structures. It is based on model updating of a Timoshenko beam resting on sway and rocking springs, which respectively represent the superstructure and the soil‐foundation system. Unlike those previously employed for this particular problem, the proposed method is a Bayesian one, which accounts for the prevailing uncertainties due to modeling and measurement errors. As such, it yields the probability distribution of the system parameters as opposed to average/deterministic values. In this approach, the joint probability density function of the parameters that control the flexible‐base Timoshenko beam model, together with the fundamental natural frequency and mode shape of the system, forms the prior distribution. Using Bayes' theorem, a posterior distribution is obtained by updating the prior distribution with a sparsely measured mode shape and frequency. The most probable realizations of the system parameters are then determined by maximizing the posterior distribution. For this purpose, first‐ and second‐order derivatives of the objective function are analytically computed via direct differentiation. The proposed method is verified using a synthetic example. Additionally, sensitivity analyses are carried out on both the system parameters and standard deviations of the sources of error. Subsequently, the proposed method is applied to real‐life data recorded at the Millikan Library building, which is located at the California Institute of Technology campus in Pasadena, California, and the results are compared with a previous deterministic study.

show abstract

Section: Introductionmentioning

confidence: 99%

Bayesian identification of soil-foundation stiffness of building structures

Shirzad-Ghaleroudkhani

Mahsuli

Ghahari

et al. 2017

Struct Control Health Monit

View full text Add to dashboard Cite

show abstract

“…The data logger used in this study could record accelerations between 0.1 mg and 2 g at a sampling rate of 200 Hz. All accelerometers were synchronized by GPS timing having accuracy of approximately 50 ns …”

Section: Dynamic Testingmentioning

confidence: 99%

System identification and modeling of a dynamically tested and gradually damaged 10‐story reinforced concrete building

Yousefianmoghadam

Behmanesh²,

Stavridis

et al. 2017

Earthq Engng Struct Dyn

View full text Add to dashboard Cite

SummaryThis paper discusses the dynamic tests, system identification, and modeling of a 10-story reinforced concrete building. Six infill walls were demolished in 3 stages during the tests to introduce damage. In each damage stage, dynamic tests were conducted by using an eccentric-mass shaker. Accelerometers were installed to record the torsional and translational responses of the building to the induced excitation, as well as its ambient vibration. The modal properties in all damage states are identified using 2 operational modal analysis methods that can capture the effect of the wall demolition. The modal identification is facilitated by a finite element model of the building. In turn, the model is validated through the comparison of the numerically and experimentally obtained modal parameters. The validated model is used in a parametric study to estimate the influence of structural and nonstructural elements on the dynamic properties of the building and to assess the validity of commonly used empirical formulas found in building codes. Issues related to the applicability and feasibility of system identification on complex structures, as well as considerations for the development of accurate, yet efficient, finite element models are also discussed.

show abstract

“…REM shakers are now relatively uncommon for testing civil structures due to severe logistical and safety constraints, a notable contemporary example being the NEES facility based in Los Angeles (Stewart et al 2005). Because heavy equipment is not required, the ambient vibration survey (AVS), coupled with operational modal analysis (OMA) is now a standard procedure.…”

Section: Ves Ambient Vibration Survey (Horizontal Modes) June 2011mentioning

confidence: 99%

Vibration monitoring and condition assessment of the University of Sheffield Arts Tower during retrofit

Koo

Basagiannis

Alskif

et al. 2013

J Civil Struct Health Monit

View full text Add to dashboard Cite

The 78m Arts Tower at the University of Sheffield was refurbished during the period 2009 to 2011, with improvements that included replacement of facades and partitions. The structural changes were reflected in changes in dynamic properties that were tracked by a combination of long-term acceleration monitoring and vibration tests to identify local and global vibration modes.The global horizontal plane modes of the building were correlated with finite element model simulations and real-time automated operational modal analysis to characterize the effects of the structural changes on horizontal vibration modes in sway and torsion. Also, floor vibration tests linked to the finite element simulations identified the contribution of 'non-structural partitions' on the floor dynamic performance.Replacement of heavy masonry partitions with modern lightweight forms has resulted in reduction of stiffness, yet there is no obvious change in sway vibration serviceability and floor performance remains satisfactory. KeywordsBuilding vibration monitoring retrofit floor sway partition 2 University of Sheffield Arts Tower history, structural details and upgradeThe University of Sheffield Arts Tower has the distinction of being the tallest university building in the UK and until 2009 was the tallest building in Sheffield. The building was completed in 1965 and is now a Grade II listed property, in recognition of its heritage status and imposing strict requirements on structural alterations including a retrofit that was completed in 2011.The building (Figure 1) has 21 storeys above ground floor (level 0), 2 basement levels, and is approximately 80m high, 36m wide and 20m deep. The basement houses lecture theatres and plant rooms which extend outside of the tower footprint and level 1 is 8.54m above level 0, with a mezzanine level. Normal floors are spaced at 3.55m intervals and as built were sub-divided by non-load bearing 75mm thick 'breezeblock' masonry partitionsThe structural frame comprises 250mm reinforced concrete (RC) flat slabs spanning between two closely spaced RC cores and RC columns arranged around the perimeter of the floors (Figure 2).There are two frame arrangements; below level 1 there are 16 perimeter rectangular columns of 965mm by 965mm, with a transfer slab to the 94 rectangular upper columns of 203mm by 406mm at 1.8m centres in the long direction and 1.12m in the short direction.Structural lateral stability is principally provided by the two reinforced concrete shear cores acting as vertical cantilevers. Lateral load is transmitted to the cores through the building cladding into the edge of each floor and then transferred by membrane plate action to the core walls. The cores are offset with regard to the floor plate long axis dividing floors into narrow and wide sides. Because of the structural eccentricity, the building's response under lateral loads involves both lateral and rotational displacement.Shortly after the Arts Tower was first occupied in 1966 a number of occupants reported perceiving moveme...

show abstract

Field Testing Capabilities of the NEES@UCLA Equipment Site for Soil-Structure Interaction Applications

Cited by 8 publications

References 9 publications

Bayesian identification of soil-foundation stiffness of building structures

Bayesian identification of soil-foundation stiffness of building structures

System identification and modeling of a dynamically tested and gradually damaged 10‐story reinforced concrete building

Vibration monitoring and condition assessment of the University of Sheffield Arts Tower during retrofit

Contact Info

Product

Resources

About