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1.
A performance-based adaptive methodology for the seismic evaluation of multi-span simply supported deck bridges 总被引：1，自引：1，他引：0
Donatello Cardone Giuseppe Perrone Salvatore Sofia 《Bulletin of Earthquake Engineering》2011,9(5):1463-1498
A performance-based adaptive methodology for the seismic assessment of highway bridges is proposed. The proposed methodology
is based on an Inverse (I), Adaptive (A) application of the Capacity Spectrum Method (CSM), with the capacity curve of the
bridge derived through a Displacement-based Adaptive Pushover (DAP) analysis. For this reason, the acronym IACSM is used to
identify the proposed methodology. A number of Performance Levels (PLs), for which the seismic vulnerability and seismic risk
of the bridge shall be evaluated, are identified. Each PL is associated to a number of Damage States (DSs) of the critical
members of the bridge (piers, abutments, joints and bearing devices). The IACSM provides the earthquake intensity level (PGA)
corresponding to the attainment of the selected DSs, using over-damped elastic response spectra as demand curves. The seismic
vulnerability of the bridge is described by means of fragility curves, derived based on the PGA values associated to each
DS. The seismic risk of the bridge is evaluated as convolution integral of the product between the fragility curves and the
seismic hazard curve of the bridge site. In this paper, the key aspects and basic assumptions of the proposed methodology
are presented first. The IACSM is then applied to nine existing simply supported deck bridges, characterized by different
types of piers and bearing devices. Finally, the IACSM predictions are compared with the results of nonlinear response time-history
analysis, carried out using a set of seven ground motions scaled to the expected PGA values. 相似文献
2.
Donatello Cardone Giuseppe Gesualdi Domenico Nigro 《Bulletin of Earthquake Engineering》2011,9(4):1227-1255
The mechanical properties of elastomers can change significantly due to air temperature variations. In particular, prolonged
exposure to subzero temperatures can result in rubber crystallization, with a considerable increase in the shear stiffness
of the material. As a result, the seismic response of structures with elastomeric isolators can be strongly influenced by
air temperature. Current seismic codes, indeed, require an upper and lower bound analysis, using suitable modification factors,
to account for the changes in the cyclic behavior of elastomeric isolators due to air temperature variations. In this study,
the sensitivity of the cyclic behavior of elastomeric isolators to air temperature variations is investigated based on the
experimental results of an extensive test program on six different elastomeric compounds for seismic isolators, characterized
by a shear modulus ranging from 0.5 to 1.2 MPa at 100% shear strain and 20°C. The cyclic tests have been performed on small-size
specimens, subjected to shear strain amplitudes and frequency of loading typical for elastomeric seismic isolators, at seven
different air temperatures, ranging from 40 to −20°C. The effects of rubber crystallization due to prolonged exposure to low-temperatures
have been also investigated. A finite element model for the evaluation of the temperature contour map inside a full-size elastomeric
isolator exposed to low air temperatures has been also developed. In the paper, the experimental outcomes are compared with
the modification factors provided by the current seismic codes to account for the temperature effects on the mechanical properties
of elastomeric isolators. 相似文献
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4.
In 1998, the Australian Government released Australia's Oceans Policy (AOP), a world first policy initiative focused on providing a framework for integrated ecosystem-based management of Australia's vast marine domain. The South East Regional Marine Plan, the first regional marine plan to be implemented under AOP, was released on 21 May 2004. This paper argues that although full integration across sectors and jurisdictions has not occurred, new AOP initiatives, institutions and governance processes have considerably increased sectoral and jurisdictional coordination in the South East region. 相似文献
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6.
The effectiveness of seismic isolation in protecting structural and non‐structural elements from damage has been assessed in an extensive programme of shaking‐table tests, carried out on four identical 1/3.3‐scale, two‐dimensional, reinforced concrete (R/C) frames. Four different isolation systems were considered, namely: (i) rubber‐based, (ii) steel‐based, (iii) shape memory alloy (SMA)‐based and (iv) hybrid, i.e. based on both SMA and steel components, isolation systems. This paper presents a comprehensive overview of the main results of the experimental tests on base‐isolated models, whose structural response is described through: (i) maximum base displacements; (ii) maximum interstorey drifts; (iii) maximum storey accelerations and (iv) maximum storey shear forces. The evolution of the fundamental frequency of vibration of the R/C frame during the tests is also described. The beneficial effects of using base isolation resulted in no or slight damage, under strong earthquakes, to both structural and non‐structural members, as well as to the internal content of the building. The comparison with the experimental results obtained in shaking‐table tests on similar fixed‐base models emphasizes these positive aspects. Finally, advantages and drawbacks related to the use of each isolation system are discussed in the paper. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
7.
T. N. Krishnamurti John Molinari Hua-Lu Pan Vince Wong 《Pure and Applied Geophysics》1977,115(5-6):1357-1372
In this short paper we have identified some of the modelling groups that have the capability of simulating or carrying out short range numerical weather prediction over the monsoon belt. We have next outlined some of the important and desirable ingredients for a multilevel primitive equation model over the tropics, with most of the emphasis on the present version of Florida State University's Tropical Prediction Model. Finally, we present briefly some important results based on the present version of our prediction models that relate to the NWP efforts over the monsoon belt. Here we have identified the importance of mountains, convection, the radiative heating balance of the earth's surface, and the planetary boundary layer over the Arabian Sea. 相似文献
8.
G. Djura&#;evi&#; I. Vince T. S. Khruzina E. Rovithis-Livaniou 《Monthly notices of the Royal Astronomical Society》2009,396(3):1553-1558
The UBV light curves of the early-type eclipsing binary V448 Cygni, obtained at the Abastumani Astrophysical Observatory from 1964 to 1967, are re-analysed here. The analysis was made assuming the presence of an accretion disc in the system, as inferred from the light-curve shape and spectroscopic characteristics of the system. The Roche model of a binary was used, containing a geometrically and optically thick accretion disc around the hotter and more massive star. By solving the inverse problem, the orbital elements and the physical parameters of the system components and of the accretion disc were estimated. This result is important for understanding the star formation and evolution processes in the systems with massive components. 相似文献
9.
Mapping block-and-ash flow hazards based on Titan 2D simulations: a case study from Mt. Taranaki,NZ 总被引：1，自引：0，他引：1
Jonathan N. Procter Shane J. Cronin Thomas Platz Abani Patra Keith Dalbey Michael Sheridan Vince Neall 《Natural Hazards》2010,53(3):483-501
Numerical models for simulation of mass flows are typically focussed upon accurately predicting the paths, travel times and
inundation from a single flow or collapse event. When considering catchment-based hazards from a volcano, this is complicated
by often being faced with several possible scenarios. Over the last 800 years at Mt. Taranaki/Egmont, a number of dome growth
and collapse events have resulted in the genesis and emplacement of block-and-ash flows (BAFs). Each BAF was directed northwestward
by a breach in the crater rim. The latest dome collapse events in the AD 1880s and AD 1755 inundated the northwestern flank
and had run-out lengths 10 km from source. Future activity of this type could have a devastating effect on the Taranaki region’s
communities, infrastructure and economy. Hazard planning has involved constructing volcanic hazard maps based upon the areas
inundated by past volcanic flows, with little consideration of present-day topography. Here, a numerical geophysical mass
flow modelling approach is used to forecast the hazards of future comparable BAF events on NW Mt. Taranaki. The Titan2D programme
encompasses a “shallow water”, continuum solution-based, granular flow model. Flow mechanical properties needed for this approach
include estimates of internal and basal friction as well as the physical dimensions of the initial collapse. Before this model
can be applied to Taranaki BAFs, the input parameters must be calibrated by simulating a range of past collapse events. By
using AD 1860 and AD 1755 scenarios, initial collapse volumes can be well constrained and internal and basal friction angles
can be evaluated through an iterative approach from previous run-out lengths. A range of possible input parameters was, therefore,
determined to produce a suite of potentially inundated areas under present-day terrain. A suite of 10 forecasts from a uniformly
distributed range were combined to create a map of relative probabilities of inundation by future BAF events. These results
were combined in a GIS package to produce hazard zones related to user-specified hazard thresholds. Using these input parameter
constraints, future hazard forecasts for this scale and type of event can also take into account changing summit and topographic
configurations following future eruptive or collapse events. 相似文献
10.