Optimal design of seismic retrofitting of RC frames with eccentric steel bracing   总被引：2，自引：1，他引：1  

Lorenzo De Stefani  Roberto Scotta  Massimiliano Lazzari 《Bulletin of Earthquake Engineering》2015,13(2):613-633

  相似文献   

Reliability of structures to earthquake clusters     

Iunio Iervolino  Massimiliano Giorgio  Barbara Polidoro 《Bulletin of Earthquake Engineering》2015,13(4):983-1002

  相似文献   

Case study of seismic performance assessment of irregular RC buildings: hospital structure of Avezzano(L’Aquila,Italy)     

Massimiliano Ferraioli 《地震工程与工程振动(英文版)》2015,(1):141-156

  相似文献   

A basal slip model for Lagrangian finite element simulations of 3D landslides          下载免费PDF全文

Massimiliano Cremonesi  Francesco Ferri  Umberto Perego 《国际地质力学数值与分析法杂志》2017,41(1):30-53

A Lagrangian numerical approach for the simulation of rapid landslide runouts is presented and discussed. The simulation approach is based on the so‐called Particle Finite Element Method. The moving soil mass is assumed to obey a rigid‐viscoplastic, non‐dilatant Drucker–Prager constitutive law, which is cast in the form of a regularized, pressure‐sensitive Bingham model. Unlike in classical formulations of computational fluid mechanics, where no‐slip boundary conditions are assumed, basal slip boundary conditions are introduced to account for the specific nature of the landslide‐basal surface interface. The basal slip conditions are formulated in the form of modified Navier boundary conditions, with a pressure‐sensitive threshold. A special mixed Eulerian–Lagrangian formulation is used for the elements on the basal interface to accommodate the new slip conditions into the Particle Finite Element Method framework. To avoid inconsistencies in the presence of complex shapes of the basal surface, the no‐flux condition through the basal surface is relaxed using a penalty approach. The proposed model is validated by simulating both laboratory tests and a real large‐scale problem, and the critical role of the basal slip is elucidated. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Wave propagation simulation in a linear viscoacoustic medium   总被引：2，自引：0，他引：2  

José M. Carcione  Dan Kosloff  Ronnie Kosloff 《Geophysical Journal International》1988,93(2):393-401

  相似文献   

Seismic and ultrasonic velocities in permafrost     

Jos M. Carcione  Gza Seriani 《Geophysical Prospecting》1998,46(4):441-454

We calculate the compressional- and shear-wave velocities of permafrost as a function of unfrozen water content and temperature. Unlike previous theories based on simple slowness and/or moduli averaging or two-phase models, we use a Biot-type three-phase theory that considers the existence of two solids (solid and ice matrices) and a liquid (unfrozen water). The compressional velocity for unconsolidated sediments obtained with this theory is close to the velocity computed with Wood's model, since Biot's theory involves a Wood averaging of the moduli of the single constituents. Moreover, the model gives lower velocities than the well-known slowness averaging theory (Wyllie's equation). For consolidated Berea sandstone, the theory underestimates the value of the compressional velocity below 0°C. Computing the average bulk moduli by slowness averaging the ice and solid phases and Wood averaging the intermediate moduli with the liquid phase yields a fairly good fit of the experimental data. The proportion of unfrozen water and temperature are closely related. Fitting the wave velocity at a given temperature allows the prediction of the velocity at the whole range of temperatures, provided that the average pore radius and its standard deviation are known.  相似文献   

Numerical simulation of ultrasonic waves in reservoir rocks with patchy saturation and fractal petrophysical properties     

J.?E.?SantosEmail author  C.?L.?Ravazzoli  P.?M.?Gauzellino  J.?M.?Carcione 《Computational Geosciences》2005,9(1):1-27

We simulate the propagation of ultrasonic waves in heterogeneous poroviscoelastic media saturated by immiscible fluids. Our model takes into account capillary forces and viscous and mass coupling effects between the fluid phases under variable saturation and pore fluid pressure. The numerical problem is solved in the space–frequency domain using a finite element procedure and the time–domain solution is obtained by a numerical Fourier transform. Heterogeneities due to fluid distribution and rock porosity–permeability are modeled as stochastic fractals, whose spectral densities reproduce saturation an petrophysical variations similar to those observed in reservoir rocks. The numerical experiments are performed at a central frequency of 500 kHz, and show clearly the effects of the different heterogeneities on the amplitudes of shear and compressional waves and the importance of wave mode conversions at the different interfaces.  相似文献   

Surface flow boundary conditions in modeling land subsidence due to fluid withdrawal     

Baú D  Ferronato M  Gambolati G  Teatini P 《Ground water》2004,42(4):516-525

Land subsidence due to subsurface fluid (water, gas, oil) withdrawal is often predicted by either finite element or finite difference numerical models based on coupled poroelastic theory, where the soil is represented as a semi-infinite medium bounded by the traction-free (ground) surface. One of the variables playing a most important role on the final outcome is the flow condition used on the traction-free boundary, which may be assumed as either permeable or impermeable. Although occasionally justified, the assumption of no-flow surface seems to be in general rather unrealistic. A permeable boundary where the fluid pressure is fixed to the external atmospheric pressure appears to be more appropriate. This paper addresses the response, in terms of land subsidence, obtained with a coupled poroelastic finite element model that simulates a distributed pumping from a horizontal aquifer confined between two relatively impervious layers, and takes either a permeable boundary surface, i.e., constant hydraulic potential, or an impermeable boundary, i.e., a zero Neumann flow condition. The analysis reveals that land subsidence is rather sensitive to the flow condition implemented on the traction-free boundary. In general, the no-flow condition leads to an overestimate of the predicted ground surface settlement, which could even be 1 order of magnitude larger than that obtained with the permeable boundary.  相似文献   

The Vallo di Diano and Auletta extensional basins in the southern Apennines (Italy): a simple model for a complex setting     

Laura Amicucci  Massimiliano R. Barchi  Paola Montone  Nicola Rubiliani 《地学学报》2008,20(6):475-482

The aim of this paper was to provide a significant case‐history concerning the evolution of a segmented system of extensional faults and related basins, investigated by a set of seismic reflection profiles. We investigated two kinematically linked semi‐grabens, developed at the hangingwall of two opposite‐dipping normal faults: the Vallo di Diano and Auletta basins, located in the southern Apennines, one of the most seismically active regions of the Italian peninsula. Our interpretation suggests that the Pliocene–Quaternary tectonic history consists of a single extensional phase, where the major NW–SE trending normal faults, generating the basins, and the strike‐slip and transtensional faults connecting adjacent normal fault segments, simultaneously act, being part of the same extensional system. We also conclude that major normal faults, bordering the basins, should be considered as potential seismogenic sources in the seismic hazard evaluation.  相似文献   

Development of an incised valley‐fill at an evolving rift margin: Pleistocene eustasy and tectonics on the southern side of the Gulf of Corinth,Greece     

Katarina Gobo  Massimiliano Ghinassi  Wojciech Nemec  Eivind Sjursen 《Sedimentology》2014,61(4):1086-1119

This study from the southern margin of the Gulf of Corinth documents a Late Pleistocene incised valley‐fill succession that differs from the existing facies models, because it comprises gravelly shoal‐water and Gilbert‐type deltaic deposits, shows strong wave influence and lacks evidence of tidal activity. The valley‐fill is at least 140 m thick, formed in 50 to 100 ka between the interglacials Marine Isotope Stage 9a and Marine Isotope Stage 7c. The relative sea‐level rise left its record both inside and outside the incised valley, and the age of the valley‐fill is estimated from a U/Th date of coral‐bearing deposits directly outside the palaeovalley outlet. Tectonic up‐warping due to formation of a valley‐parallel structural relay ramp contributed to the valley segmentation and limited the landward extent of marine invasions. The valley segment upstream of the ramp crest was filled with a gravelly alluvium, whereas the downstream segment accumulated fluvio‐deltaic deposits. The consecutive deltaic systems nucleated in the ramp‐crest zone, forming a bathymetric gradient that promoted the ultimate growth of thick Gilbert‐type delta. The case study contributes to the spectrum of conceptual models for incised valley‐fill architecture. Four key models are discussed with reference to the rates of sediment supply and accommodation development, and it is pointed out that not only similarity, but also all departures of particular field cases from these end‐member models may provide valuable information on the system formative conditions. The Akrata incised valley‐fill represents conditions of high sediment supply and a rapid, but stepwise development of accommodation that resulted from the spatiotemporal evolution of normal faulting at the rift margin and overprinted glacioeustatic signals. This study adds to an understanding of valley‐fill architecture and provides new insights into the Pleistocene tectonics and palaeogeography of the Corinth Rift margin.  相似文献