4,129 research outputs found
PEER Testbed Study on a Laboratory Building: Exercising Seismic Performance Assessment
From 2002 to 2004 (years five and six of a ten-year funding cycle), the PEER Center organized
the majority of its research around six testbeds. Two buildings and two bridges, a campus, and a
transportation network were selected as case studies to âexerciseâ the PEER performance-based
earthquake engineering methodology. All projects involved interdisciplinary teams of
researchers, each producing data to be used by other colleagues in their research. The testbeds
demonstrated that it is possible to create the data necessary to populate the PEER performancebased framing equation, linking the hazard analysis, the structural analysis, the development of
damage measures, loss analysis, and decision variables.
This report describes one of the building testbedsâthe UC Science Building. The project
was chosen to focus attention on the consequences of losses of laboratory contents, particularly
downtime. The UC Science testbed evaluated the earthquake hazard and the structural
performance of a well-designed recently built reinforced concrete laboratory building using the
OpenSees platform. Researchers conducted shake table tests on samples of critical laboratory
contents in order to develop fragility curves used to analyze the probability of losses based on
equipment failure. The UC Science testbed undertook an extreme case in performance
assessmentâlinking performance of contents to operational failure. The research shows the
interdependence of building structure, systems, and contents in performance assessment, and
highlights where further research is needed.
The Executive Summary provides a short description of the overall testbed research
program, while the main body of the report includes summary chapters from individual
researchers. More extensive research reports are cited in the reference section of each chapter
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Synthesis of accelerograms compatible with the Chinese GB 50011-2001 design spectrum via harmonic wavelets: artificial and historic records
A versatile approach is employed to generate artificial accelerograms which satisfy the compatibility criteria prescribed by the Chinese aseismic code provisions GB 50011-2001. In particular, a frequency dependent peak factor derived by means of appropriate Monte Carlo analyses is introduced to relate the GB 50011-2001 design spectrum to a parametrically defined evolutionary power spectrum (EPS). Special attention is given to the definition of the frequency content of the EPS in order to accommodate the mathematical form of the aforementioned design spectrum. Further, a one-to-one relationship is established between the parameter controlling the time-varying intensity of the EPS and the effective strong ground motion duration. Subsequently, an efficient auto-regressive moving-average (ARMA) filtering technique is utilized to generate ensembles of non-stationary artificial accelerograms whose average response spectrum is in a close agreement with the considered design spectrum. Furthermore, a harmonic wavelet based iterative scheme is adopted to modify these artificial signals so that a close matching of the signalsâ response spectra with the GB 50011-2001 design spectrum is achieved on an individual basis. This is also done for field recorded accelerograms pertaining to the May, 2008 Wenchuan seismic event. In the process, zero-phase high-pass filtering is performed to accomplish proper baseline correction of the acquired spectrum compatible artificial and field accelerograms. Numerical results are given in a tabulated format to expedite their use in practice
Seismic vulnerability assessment: Methodological elements and applications to the case of Romania
This paper is intended to present some studies undertaken in order to develop a seismic vulnerability estimation system to fit the needs of development of earthquake scenarios and of development of an integrated disaster risk management system for Romania. Methodological aspects are dealt with, in connection with the criteria of categorization of buildings, with the definition of parameters used for characterizing vulnerability, with the setting up of an inventory of buildings and with the calibration of parameters characterizing vulnerability. Action was initiated along the coordinates referred to in connection with the methodological aspects mentioned above. The approach was made, as far as possible, specific to the conditions of Romania. Some data on results obtained to date are presented.seismic vulnerability, vulnerability estimation, earthquake scenarios, categorization of buildings, inventory of buildings, expected earthquake impact
Impact of New Madrid Seismic Zone Earthquakes on the Central USA, Vol. 1 and 2
The information presented in this report has been developed to support the Catastrophic Earthquake Planning Scenario workshops held by the Federal Emergency Management Agency. Four FEMA Regions (Regions IV, V, VI and VII) were involved in the New Madrid Seismic Zone (NMSZ) scenario workshops. The four FEMA Regions include eight states, namely Illinois, Indiana, Kentucky, Tennessee, Alabama, Mississippi, Arkansas and Missouri.
The earthquake impact assessment presented hereafter employs an analysis methodology comprising three major components: hazard, inventory and fragility (or vulnerability). The hazard characterizes not only the shaking of the ground but also the consequential transient and permanent deformation of the ground due to strong ground shaking as well as fire and flooding. The inventory comprises all assets in a specific region, including the built environment and population data. Fragility or vulnerability functions relate the severity of shaking to the likelihood of reaching or exceeding damage states (light, moderate, extensive and near-collapse, for example). Social impact models are also included and employ physical infrastructure damage results to estimate the effects on exposed communities. Whereas the modeling software packages used (HAZUS MR3; FEMA, 2008; and MAEviz, Mid-America Earthquake Center, 2008) provide default values for all of the above, most of these default values were replaced by components of traceable provenance and higher reliability than the default data, as described below.
The hazard employed in this investigation includes ground shaking for a single scenario event representing the rupture of all three New Madrid fault segments. The NMSZ consists of three fault segments: the northeast segment, the reelfoot thrust or central segment, and the southwest segment. Each segment is assumed to generate a deterministic magnitude 7.7 (Mw7.7) earthquake caused by a rupture over the entire length of the segment. US Geological Survey (USGS) approved the employed magnitude and hazard approach. The combined rupture of all three segments simultaneously is designed to approximate the sequential rupture of all three segments over time. The magnitude of Mw7.7 is retained for the combined rupture. Full liquefaction susceptibility maps for the entire region have been developed and are used in this study.
Inventory is enhanced through the use of the Homeland Security Infrastructure Program (HSIP) 2007 and 2008 Gold Datasets (NGA Office of America, 2007). These datasets contain various types of critical infrastructure that are key inventory components for earthquake impact assessment. Transportation and utility facility inventories are improved while regional natural gas and oil pipelines are added to the inventory, alongside high potential loss facility inventories. The National Bridge Inventory (NBI, 2008) and other state and independent data sources are utilized to improve the inventory. New fragility functions derived by the MAE Center are employed in this study for both buildings and bridges providing more regionally-applicable estimations of damage for these infrastructure components. Default fragility values are used to determine damage likelihoods for all other infrastructure components.
The study reports new analysis using MAE Center-developed transportation network flow models that estimate changes in traffic flow and travel time due to earthquake damage. Utility network modeling was also undertaken to provide damage estimates for facilities and pipelines. An approximate flood risk model was assembled to identify areas that are likely to be flooded as a result of dam or levee failure. Social vulnerability identifies portions of the eight-state study region that are especially vulnerable due to various factors such as age, income, disability, and language proficiency. Social impact models include estimates of displaced and shelter-seeking populations as well as commodities and medical requirements. Lastly, search and rescue requirements quantify the number of teams and personnel required to clear debris and search for trapped victims.
The results indicate that Tennessee, Arkansas, and Missouri are most severely impacted. Illinois and Kentucky are also impacted, though not as severely as the previous three states. Nearly 715,000 buildings are damaged in the eight-state study region. About 42,000 search and rescue personnel working in 1,500 teams are required to respond to the earthquakes. Damage to critical infrastructure (essential facilities, transportation and utility lifelines) is substantial in the 140 impacted counties near the rupture zone, including 3,500 damaged bridges and nearly 425,000 breaks and leaks to both local and interstate pipelines. Approximately 2.6 million households are without power after the earthquake. Nearly 86,000 injuries and fatalities result from damage to infrastructure. Nearly 130 hospitals are damaged and most are located in the impacted counties near the rupture zone. There is extensive damage and substantial travel delays in both Memphis, Tennessee, and St. Louis, Missouri, thus hampering search and rescue as well as evacuation. Moreover roughly 15 major bridges are unusable. Three days after the earthquake, 7.2 million people are still displaced and 2 million people seek temporary shelter. Direct economic losses for the eight states total nearly $300 billion, while indirect losses may be at least twice this amount.
The contents of this report provide the various assumptions used to arrive at the impact estimates, detailed background on the above quantitative consequences, and a breakdown of the figures per sector at the FEMA region and state levels. The information is presented in a manner suitable for personnel and agencies responsible for establishing response plans based on likely impacts of plausible earthquakes in the central USA.Armu W0132T-06-02unpublishednot peer reviewe
Advancing performance-based design and assessment of exposed column base plates and welded column splices in steel moment resisting frames
Exposed column base plate (ECBP) and welded column splice (WCS) connections are critical load-carrying structural connections and are commonly used in steel moment-resisting frames (SMRFs). However, they have received relatively lower research attention than welded beam-to-column (WBC) connections, leaving several relevant aspects of their performance and their effects on the overall seismic performance of SMRFs not well investigated. For instance, although the current design approach for ECBP connections is relatively well-established from a mechanistic standpoint, the reliability of such designed connections (i.e., the structural performance of ECBPs at the design level) is not as well understood. Therefore, some prospective refinements to the current approach may be developed to ensure acceptable and consistent failure probabilities across the various components of the ECBP connections. In the context of WCS connections constructed before the 1994 Northridge earthquake (i.e., pre-Northridge WCSs), their potential fracture due to earthquake shaking has been recently revealed in some research studies. However, these studies did not take advantage of recent advancements in performance-based earthquake engineering (PBEE), and made several simplifying assumptions for practical purposes. Some refinements and research tools within the PBEE framework may be required to more accurately estimate the fracture demand and capacity distributions, and the associated fragility and risk of pre-Northridge WCSs. This doctoral dissertation attempts to address these mentioned issues in a rigorous manner. Specifically, this dissertation presents the following research studies: 1. Detailed reliability analysis of ECBPs designed as per the current design method and two modified approaches (improved from the current one) for a set of 59 design scenarios subjected to combinations of gravity, wind, and seismic loads. This also includes the Monte Carlo sampling to characterize the uncertainty sources in the load, material properties, component geometry, and demand/capacity models for various components within the connection. 2. Refined probabilistic fracture fragility assessment of pre-Northridge WCSs, accounting for the seismic demand and fracture capacity uncertainties. Optimal ground-motion intensity measures, the effect of vertical ground accelerations, and the WCS capacity uncertainties are included to improve the fracture fragility estimation. 3. Expanded fracture fragility and risk assessment of pre-Northridge WCSs in near-fault regions to address the effect of pulse-like ground motions on the distribution/increase of WCS seismic demands. Near-source probabilistic seismic hazard analysis is conducted to facilitate the fracture risk assessment. The findings of the first study can contribute to the better scientific knowledge of reliability-based design and assessment of ECBP connections in SMRFs, whereas the last two studies can help better understand the fracture risk of WCS connections in SMRFs, and inform the planning of retrofitting strategies
Ground motion selection for simulation-based seismic hazard and structural reliability assessment
This paper examines four methods by which ground motions can be selected for
dynamic seismic response analyses of engineered systems when the underlying
seismic hazard is quantified via ground motion simulation rather than empirical
ground motion prediction equations. Even with simulation-based seismic hazard, a
ground motion selection process is still required in order to extract a small number of
time series from the much larger set developed as part of the hazard calculation. Four
specific methods are presented for ground motion selection from simulation-based
seismic hazard analyses, and pros and cons of each are discussed via a simple and
reproducible illustrative example. One of the four methods (method 1 âdirect
analysisâ) provides a âbenchmarkâ result (i.e. using all simulated ground motions),
enabling the consistency of the other three more efficient selection methods to be
addressed. Method 2 (âstratified samplingâ) is a relatively simple way to achieve a
significant reduction in the number of ground motions required through selecting
subsets of ground motions binned based on an intensity measure, IM. Method 3
(âsimple multiple stripesâ) has the benefit of being consistent with conventional
seismic assessment practice using as-recorded ground motions, but both methods 2
and 3 are strongly dependent on the efficiency of the conditioning IM to predict the
seismic responses of interest. Method 4 (âGCIM-based selectionâ) is consistent with
âadvancedâ selection methods used for as-recorded ground motions, and selects
subsets of ground motions based on multiple IMs, thus overcoming this limitation in
methods 2 and 3
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