Seismic Evaluation

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Guidelines for the seismic evaluation of existing buildings

Guidelines for the seismic evaluation of existing buildings

Guidelines for the seismic evaluation of existing buildings Allen, D. E.; Rainer, J. H. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Seismic Evaluation and Retrofit of Existing Concentrically Braced Steel Frames in Canada

Seismic Evaluation and Retrofit of Existing Concentrically Braced Steel Frames in Canada

yielding, with detrimental consequences on frame response. This more critical failure mode has not been investigated in the past and this study can provide additional data needed to establish the limits on acceptable beam demand-to-capacity ratios. In the U.S, seismic evaluation of existing buildings is carried out using the requirements and procedures defined in the ASCE 41-13 standard (ASCE 2013). To satisfy the basic performance objective (BPOE), an existing building must attain life safety performance level for seismic hazard with probability of exceedance of 20% in 50 years and collapse prevention level under the seismic hazard with probability of exceedance of 5% in 50 years. ASCE 41 also specifies acceptance criteria for existing structures that are different from those used for new structures. Less stringent performance objectives compared to new constructions account for the facts that: (i) existing buildings have a shorter remaining life, (ii) more recent constructions do not become deficient with every more conservative changes in design codes, and (iii) the high cost associated with the higher level of performance cannot be justified in view of the incremental benefit. In Canada, according to NBCC 2010 (NRCC 2010), initial assessment is carried out using reduced loads corresponding to 60% of earthquake loads prescribed for new buildings that are established for a probability of exceedance of 2% in 50 years. Thus, unlike in the U.S., the seismic hazard used for the assessment of existing buildings is not related to a specific probability of exceedance. When triggered, the retrofit should be designed for higher force levels, preferably meeting the performance objective for new buildings, i.e. collapse prevention for a probability of exceedance of 2% in 50 years, taking into considerations of future building use, control of seismic damage and the differential in upgrading costs with force levels (Allen et al. 1992). Acceptance criteria used for assessment and retrofit are those prescribed for new constructions. Past studies (e.g., Harris and Speicher 2015, Speicher and Harris 2016, Balazadeh-Minouei et al. 2017) have shown that the seismic assessment of steel concentrically braced frames is heavily influenced by the analysis method used. Evaluation procedures using linear analysis can yield less or more conservative results compared to nonlinear analysis, depending on the components being verified. Harris and Speicher (2015) also concluded that nonlinear procedures provide a more rigorous assessment compared to linear procedures and that more research is needed to determine appropriate acceptance criteria for beam-columns.
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Seismic evaluation of concrete dams

Seismic evaluation of concrete dams

Hall, J.F., Chopra, A.K., "Two Dimensional Dynamic Analysis of Concrete Gravity and Embankment Dams Including Hydrodynamic Effects", Earthquake Engineering and Struc[r]

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Guidelines for seismic evaluation of existing buildings

Guidelines for seismic evaluation of existing buildings

Building components are organized into the following subsystems: vertical elements resisting horizontal loads (i.e., moment- resisting frames, shear walls, and braced frames); horizontal[r]

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Seismic evaluation and upgrading of buildings

Seismic evaluation and upgrading of buildings

How ever, th e NBC-sp ecified seism ic load is red u ced by 40% for existin g bu ild in gs becau se of th e large cost associated w ith stru ctu ral in terven tion com p ared to [r]

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2010 — Performance-based seismic vulnerability evaluation of existing buildings in old sectors of Quebec

2010 — Performance-based seismic vulnerability evaluation of existing buildings in old sectors of Quebec

3.3.2 Application of AEM in the Incremental Dynamic Analysis In a performance base seismic evaluation (PBSE) process, the calculated responses are sensitive to the characteristics of the individual ground motion used as the seismic input. Therefore, different ground motion records are required to obtain a good estimation of the building’s responses. To this end, the Incremental Dynamic Analysis (IDA) is shown to be an effective tool for thoroughly examining the structural performance of buildings under seismic loads (Christovasilis, Filiatrault et al. 2009; Lagaros 2009). An IDA involves subjecting a structural model to various ground motion records, each scaled to multiple levels of intensity up to the point at which a limit state is reached (Vamvatsikos and Cornell 2002). The approach has the potential to demonstrate the variation of structural responses, as measured by a damage measure (DM, e.g., inter-storey drift), versus the ground motion intensity level, measured by an intensity measure (IM, e.g., peak ground acceleration or the first-mode spectral acceleration). In other words, the IDA procedure provides dynamic capacity curves for different ground motion levels.
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Conditional Mean Spectra, Spectral Correlation Coefficients, and High Damping Spectral Amplitudes for Seismic Design and Evaluation in Canada

Conditional Mean Spectra, Spectral Correlation Coefficients, and High Damping Spectral Amplitudes for Seismic Design and Evaluation in Canada

3.1 Introduction The NBCC (2005, 2010) prescribes uniform hazard spectrum (UHS) with a probability of exceedence of 2% in 50 years. The prescribed UHS accelerations are specific to each site of interest and correspond to a given probability of exceedance and do not represent an individual seismic event. The appropriateness of the UHS as a target for seismic safety assessment is debatable because of its inherent conservatism. As an alternative, the conditional mean spectrum (CMS) has been proposed (Baker 2011). A CMS is a mean response spectrum computed based on the condition that spectral acceleration matches a target amplitude at a given period. The U.S. geological survey (USGS 2010) provides online tools to compute CMS for both eastern and western regions of the United States. However, these are based on ground motion models adopted for the seismic hazard in the United States, while development and application of CMS in eastern Canada have not yet been explored. This work addresses (i) the construction of the CMS considering seismic hazard in Montreal, (ii) the application of this CMS for seismic evaluation of an existing 8-storey reinforced concrete shear wall building located in Montreal, and (iii) comparison of the results to those obtained using conventional UHS. As addressed in Hong et al. (2006) and Hong and Goda (2006), nonnormal distribution of the probabilistic seismic hazard analysis results, to determine the UHS, does not provide very uniform spectral amplitudes in terms of probability of exceedance when the median of the results are considered rather than the mean. Nevertheless, this is the approach taken by the GSC to determine the UHS amplitudes provided in the NBCC (2005, 2010). The main objective of this note is to shed light on the usage of CMS in eastern Canada with the currently available tools such as the UHS prescribed in the NBCC, which is the only tool that the engineering community is provided with and is regarded as a representative of the 2% in 50 year probability of exceedance at all periods.
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Seismic performance of wood mid-rise structures

Seismic performance of wood mid-rise structures

4 A REVIEW ON NUMERICAL MODELING Different numerical models have been developed to simulate the complex behaviour of timber structures during seismic events. There are several challenges in performing a structural analysis for timber buildings subjected to the seismic load. Wood is a hygroscopic (ability to attract moisture from the air), anisotropic material (its structure and properties vary in different directions) of biological origin. The biological origin of wood means its diversity and variation, between and within different species of trees. These characteristics of wood make the prediction of its material properties very complex and difficult for analysis and numerical modeling. Woods are considered among the most highly nonlinear materials. In addition, the strength of wood members depends on moisture content, direction of grain, and defects (i.e. splits); wood strength is also affected by heat and water exposure, and fungus. Consequently, for the analysis of a structure subjected to a seismic load, a nonlinear analysis is required since the linear analysis may not be sufficient.
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Mantle structural geology from seismic anisotropy

Mantle structural geology from seismic anisotropy

as representative of the lithosphere in the depth range of 120-170 km based on geobarometry. They appear to be undisturbed by the eruption process (in contrast to the sheared nodules). The elastic properties of the aggregates were determined b y petrofabric analysis of the samples, knowledge of the single-crystal elastic constants and their temperature and pressure derivatives. The analysis of these samples allows the aggregate elasticity matrix to be placed in a structural frame. This characterization of the elasticity matrix and its placement in the structural frame is perhaps the most important step in the interpretation of seismic anisotropy, as it provides the critical link between orientation of deformation and orientation of anisotropy. In this initial study, 5 such samples were averaged in the structural frame. Such an average would be appropriate for seismic waves as long as the deformation is spatially coherent. It i s thus an upper bound on the actual detectable anisotropy. In that study it was found that the maximum shear-wave anisotropy was 3.7%, while anisotropy for propagation along the three structural directions yielded 1.7%, 3.1%, and 1.6% for the X ,
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Question about the seismic cycle of the East Anatolian Fault and its seismic versus aseismic behavior

Question about the seismic cycle of the East Anatolian Fault and its seismic versus aseismic behavior

Our record demonstrates that Hazar Lake has repeatedly sustained large seismic shaking. The earthquake source might located exactly at the lake location where the master fault could be creeping, but seismic sources along the EAF or on secondary structures near the location of Hazar Lake still generated repeatedly large magnitude earthquakes.

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Seismic velocities, anisotropy and elastic properties of crystalline rocks and implications for interpretation of seismic data

Seismic velocities, anisotropy and elastic properties of crystalline rocks and implications for interpretation of seismic data

surface-derived samples be reliably extrapolated to the Earth’s interior if these samples have been long exposed to weathering and have experienced alteration along microcracks and grain boundaries? Thus, it is of the utmost importance to quantify the seismic properties of unaltered rock samples from greater depths. The Chinese Continental Scientific Drilling (CCSD) project, which drilled to a depth of 5158 meters into the ultrahigh pressure (UHP) metamorphic terrane in the Sulu region of central eastern China, provides a complete suite of unaltered, rare UHP metamorphic rock samples for measurements of seismic properties. In Chapter 3, the Vp-pressure behaviors of deep core samples from the CCSD borehole are compared with their surface equivalents. The comparison suggests that the high pressure data from the core samples are much more reliable for extrapolation to deeper crust than the data from surface analogues that have been subjected to long histories of weathering and alteration along intergranular and transgranular cracks. Furthermore, Chapter 3 presents new results on P- and S-wave velocities, hysteresis, Vp anisotropy and shear wave splitting as a function of confining pressure up to 800 MPa for a suite of 22 samples collected from the CCSD main hole. The results of this study provide insight into the origin of hysteresis, anisotropy and shear wave splitting and the reflectivity of the UHP metamorphic rocks from the Sulu orogenic belt and perhaps other HP/UHP metamorphic terranes throughout the world. One of the main focuses of the investigation is to elucidate the role of microcrack preferred orientations on seismic anisotropy and shear wave splitting.
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Modelling of masonry walls under seismic loadings

Modelling of masonry walls under seismic loadings

The structure of the thesis reflects the outlined modelling strategy. Its content is organized as follows: • Chapter 1 reports the development of an analytical homogenisation method for the eval- uation of the in-plane strength of masonry. The method is presented as the extension to the Cosserat continuum of a procedure formulated in the literature for the Cauchy con- tinuum. It is based on the two-dimensional micropolar continuum theory and makes use of the kinematic approach of limit analysis in conjunction with a rigorous homogenisa- tion technique. The method is first presented with regard to a generic periodic collection of rigid blocks in contact. Next it is generalized to the whole class of discrete periodic media made of particles of the same type. The case of masonry is presented as applica- tion. The homogenised strength domains of masonry columns and walls are formulated in terms of the deformation measures of the Cosserat continuum. They are then projected into the space of the generalized stresses and couple stresses. This allows to retrieve the homogenised yield criteria for masonry. The formulation of the method based on the Cosserat continuum enables to investigate the influence of the relative rotation of the particles on the strength of the discrete medium. This influence is highlighted by the application to masonry, in comparison with the method based on the Cauchy continuum. • Chapter 2 continues the development of the method presented in the previous Chapter, by extending it to the evaluation of the coupled in-plane and out-of-plane strength of masonry. The method is illustrated first for discrete periodic media made of particles disposed along three directions and showing three periodicity vectors. It relies on the use of the kinematic approach of limit analysis, developed, in this case, within the framework of the three- dimensional micropolar theory. This enables to capture the three-dimensional effect of both the relative translations and the relative rotations of the particles constituting the discrete medium. The application to masonry columns and walls shows how the in-plane and out-of-plane actions are coupled in the assessment of masonry strength. The relative rotations of the blocks accentuate this effect, which reduces the in-plane strength and suggests the use of three-dimensional models for masonry. Masonry walls are ascribed at the end of this Chapter to homogenised plates with Cosserat kinematics.
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A seismic probability map for Canada

A seismic probability map for Canada

A seismic probability map for Canada Hodgson, J. H. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Cased Borehole Effect On Downhole Seismic Measurements

Cased Borehole Effect On Downhole Seismic Measurements

The examples in this section show that: (1) the cased borehole effect on downhole geo- phone measurements is minimal for frequency below 1 kHz for the hard formation and 500 Hz for the s[r]

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Automated fault detection without seismic processing

Automated fault detection without seismic processing

Implementation and results In terms of computing, the training process takes a few hours per data set and minutes for testing. Putting this in perspective, the training process for one data set takes the same time that the migration of a single shot takes for a dense acquisi- tion with anisotropic assumption. Once the network is trained, it can be reused many times with minimal cost, and given a certain generalization level, it can be exposed to many new data sets. This can be far less expensive than processing and interpret- ing one complete seismic acquisition, which happens every time the underlying model is changed. Our proprietary workflow is almost completely implemented in the MIT Julia language in which the heavy computing is offloaded to GPGPUs through NVIDIA’s CuDNN.
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Guideline for Seismic Upgrading of Building Structures

Guideline for Seismic Upgrading of Building Structures

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Guideline for Seismic Upgrading of Building Structures https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Aftershocks in engineering seismic risk analysis.

Aftershocks in engineering seismic risk analysis.

(2) The relative contribution of aftershocks to the total seismic risk increases with increasing upper bounds on the mainshock magnitudes, which implies that the afte[r]

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Understanding seismic heterogeneities in the lower mantle beneath the Americas from seismic tomography and plate tectonic history

Understanding seismic heterogeneities in the lower mantle beneath the Americas from seismic tomography and plate tectonic history

[ 6 ] With certain assumptions, seismically fast anomalies at a given depth in the mantle can be correlated with slab frag- ments due to past episodes of subduction. Grand [1994] showed that beneath South America no fast (slab like) anoma- lies are present beneath 1300 km depth, which he explained by the reduction in convergence of the Nazca/Farallon plate prior to 60 Myr. Bunge and Grand [2000] showed that the slab bend observed in tomographic images between 900 and 1500 km depth beneath the eastern part of North America can be explained by low-angle subduction of young lithosphere created between the separating Kula and Farallon plates during the Mesozoic. This low-angle subduction had been invoked Figure 1. Location map of earthquakes (black stars) and seismic stations (white triangles) used in this
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Red-giant seismic properties analyzed with CoRoT

Red-giant seismic properties analyzed with CoRoT

Aims. We perform an analysis of more than 4600 CoRoT light curves to extract as much information as possible. We take into account the characteristics of both the star sample and the method to ensure that our asteroseismic results are as unbiased as possible. We also study and compare the properties of red giants in two opposite regions of the Galaxy. Methods. We analyze the time series using the envelope autocorrelation function to extract precise asteroseismic parameters with reliable error bars. We examine first the mean wide frequency separation of solar-like oscillations and the frequency of the maximum seismic amplitude, then the parameters of the excess power envelope. With the additional information of the effective temperature, we derive the stellar mass and radius.
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Applying Compactness Constraints to Seismic Traveltime Tomography

Applying Compactness Constraints to Seismic Traveltime Tomography

Daley, T., L. Myer, and E. Majer (2005), Acquisition of time-lapse, 6-component, P- and S-wave, crosswell seismic survey with an orbital vibrator and of time-lapse vsp for CO2 injection monitoring, in SEG International Exposition and 75th Ann. Mtg, Soc.Of Expl. Geophysocs. Day-Lewis, F., J. Lane, J. Harris, and S. Gorelick (2003), Time-lapse imaging of saline tracer tests using cross-borehole radar tomography, Water Resources Research, 39 (10), doi:10.1029/2002WR001722. Farquharson, C. G., and D. W. Oldenburg (1998), Non-linear inversion using general measures of data misfit

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