An answer to an important controversy and the need for caution when using simple models to predict inelastic earthquake response of buildings with torsion

This paper presents evidence that the extension of conclusions based on the widely used simplified, one story, eccentric systems of the shear‐beam type, to actual, nonsymmetric buildings and consequent assessments of the pertinent code provisions, can be quite erroneous, unless special care is taken to match the basic properties of the simplified models to those of the real buildings. The evidence comes from comparisons of results obtained using three variants of simplified models, with results from the inelastic dynamic response of three‐ and five‐story eccentric buildings computed with detailed MDOF systems, where the members are idealized with the well‐known plastic hinge model. In addition, a convincing answer is provided on a pertinent hanging controversy: For frame‐type buildings, designed in accordance with the dynamic provisions of modern codes (such as EC8 or IBC2000), which allow reduced shears at the stiff edge due to torsion, the frames at the flexible sides are the critical elements in terms of ductility demands. Copyright © 2009 John Wiley & Sons, Ltd.     

Manganese in runoff from upland catchments: temporal patterns and controls on mobilization / Teneur en manganèse de l'écoulement en bassins versants d'altitude: variations temporelles et contrôles de la mobilisation

Abstract

Knowledge of the hydrochemical dynamics of the trace metal manganese (Mn) in upland catchments is required for water quality management. Stream water Mn and other solutes and flow were monitored in two upland catchments in northern England with different soils: one dominated by peat (HS7), the other by mineral soils (HS4). Maximum Mn concentrations occurred at different times in the two catchments: in summer baseflow at HS4 and during late summer storm events at HS7. A two-component chemical mixing model was used to identify the hydrological processes controlling Mn concentrations in stream water. This approach was more successful for HS4 than HS7, probably because of different processes of Mn release in the two catchments and also difficulties in selecting conservative solutes. Factor analysis of the stream water chemistry data set for each catchment was more useful in identifying the controls on Mn release into runoff. The factors indicate that the main source of Mn at HS4 is the hydrological pathway supplying summer baseflow, whereas at HS7 Mn is released during the rewetting of dried peat soils. Manganese concentrations in stream water in upland catchments appear to depend on soil type and antecedent moisture conditions. This has implications for the design of sampling strategies in upland catchments and also for managing the quality of water supplies from such areas.     

Assessing uncertainties in a conceptual water balance model using Bayesian methodology / Estimation bayésienne des incertitudes au sein d’une modélisation conceptuelle de bilan hydrologique

Abstract

Abstract The aim of this study was to estimate the uncertainties in the streamflow simulated by a rainfall–runoff model. Two sources of uncertainties in hydrological modelling were considered: the uncertainties in model parameters and those in model structure. The uncertainties were calculated by Bayesian statistics, and the Metropolis-Hastings algorithm was used to simulate the posterior parameter distribution. The parameter uncertainty calculated by the Metropolis-Hastings algorithm was compared to maximum likelihood estimates which assume that both the parameters and model residuals are normally distributed. The study was performed using the model WASMOD on 25 basins in central Sweden. Confidence intervals in the simulated discharge due to the parameter uncertainty and the total uncertainty were calculated. The results indicate that (a) the Metropolis-Hastings algorithm and the maximum likelihood method give almost identical estimates concerning the parameter uncertainty, and (b) the uncertainties in the simulated streamflow due to the parameter uncertainty are less important than uncertainties originating from other sources for this simple model with fewer parameters.     

Integration of remote sensing data into hydrological models for reservoir management

Abstract

The purpose of this paper is to present the methodology set up to derive catchment soil moisture from Earth Observation (EO) data using microwave spaceborne Synthetic Aperture Radar (SAR) images from ERS satellites and to study the improvements brought about by an assimilation of this information into hydrological models. The methodology used to derive EO data is based on the appropriate selection of land cover types for which the radar signal is mainly sensitive to soil moisture variations. Then a hydrological model is chosen, which can take advantage of the new information brought by remote sensing. The assimilation of soil moisture deduced from EO data into hydrological models is based principally on model parameter updating. The main assumption of this method is that the better the model simulates the current hydrological system, the better the following forecast will be. Another methodology used is a sequential one based on Kalman filtering. These methods have been put forward for use in the European AIMWATER project on the Seine catchment upstream of Paris (France) where dams are operated to alleviate floods in the Paris area.     

Explicit integration of bounding surface model for the analysis of earthquake soil liquefaction

This paper presents a new plasticity model developed for the simulation of monotonic and cyclic loading of non‐cohesive soils and its implementation to the commercial finite‐difference code FLAC, using its User‐Defined‐Model (UDM) capability. The new model incorporates the framework of Critical State Soil Mechanics, while it relies upon bounding surface plasticity with a vanished elastic region to simulate the non‐linear soil response. Stress integration of constitutive relations is performed using a recently proposed explicit scheme with automatic error control and substepping, which so far has been employed in the literature only for constitutive models aiming at monotonic loading. The overall accuracy of this scheme is evaluated at element level by simulating cyclic loading along complex stress paths and by using iso‐error maps for paths involving change of the Lode angle. The performance of the new constitutive model and its stress integration scheme in complex boundary value problems involving earthquake‐induced liquefaction is evaluated, in terms of accuracy and computational cost, via a number of parametric analyses inspired by the successful simulation of the VELACS centrifuge Model Test No. 2 studying the lateral spreading response of a liquefied sand layer. Copyright © 2009 John Wiley & Sons, Ltd.     

Crustal structure of the Ordovician Macquarie Arc,Eastern Lachlan Orogen,based on seismic‐reflection profiling

In the Eastern Lachlan Orogen, the mineralised Molong and Junee‐Narromine Volcanic Belts are two structural belts that once formed part of the Ordovician Macquarie Arc, but are now separated by younger Silurian‐Devonian strata as well as by Ordovician quartz‐rich turbidites. Interpretation of deep seismic reflection and refraction data across and along these belts provides answers to some of the key questions in understanding the evolution of the Eastern Lachlan Orogen—the relationship between coeval Ordovician volcanics and quartz‐rich turbidites, and the relationship between separate belts of Ordovician volcanics and the intervening strata. In particular, the data provide evidence for major thrust juxtaposition of the arc rocks and Ordovician quartz‐rich turbidites, with Wagga Belt rocks thrust eastward over the arc rocks of the Junee‐Narromine Volcanic Belt, and the Adaminaby Group thrust north over arc rocks in the southern part of the Molong Volcanic Belt. The seismic data also provide evidence for regional contraction, especially for crustal‐scale deformation in the western part of the Junee‐Narromine Volcanic Belt. The data further suggest that this belt and the Ordovician quartz‐rich turbidites to the east (Kirribilli Formation) were together thrust over ?Cambrian‐Ordovician rocks of the Jindalee Group and associated rocks along west‐dipping inferred faults that belong to a set that characterises the middle crust of the Eastern Lachlan Orogen. The Macquarie Arc was subsequently rifted apart in the Silurian‐Devonian, with Ordovician volcanics preserved under the younger troughs and shelves (e.g. Hill End Trough). The Molong Volcanic Belt, in particular, was reworked by major down‐to‐the‐east normal faults that were thrust‐reactivated with younger‐on‐older geometries in the late Early ‐ Middle Devonian and again in the Carboniferous.     

Generation of correlated properties in heterogeneous porous media

The spatial distribution of rock properties in porous media, such as permeability and porosity, often is strongly variable. Therefore, these properties usefully may be considered as a random field. However, this variability is correlated frequently on length scales comparable to geological lengths (for example, scales of sand bodies or facies). To solve various engineering problems (for example, in the oil recovery process) numerical models of a porous medium often are used. A need exists then to understand correlated random fields and to generate them over discretized numerical grids. The paper describes the general mathematical methods required to do this, with one particular method (the nearest neighbor model) described in detail. How parameters of the mathematical model may be related to rock property statistics for the nearest neighbor model is shown. The method is described in detail in one, two, and three dimensions. Examples are given of how model parameters may be determined from real data.     

Rockburst research at Falconbridge's Strathcona Mine,Sudbury, Canada

Microseismic systems at five mines in the Sudbury Basin provide the basic data for Falconbridge Limited's rockburst research. Daily and long-term analysis of this data as well as underground observations have confirmed the fault-slip mechanism at three mines. A detailed analysis of the complete history of Falconbridge Mine is being conducted and Distinct Element numerical models are being used to simulate both the stick-slip behaviour of faults and the dynamic effects of the induced vibrations on rock and backfill. University research includes acoustic tomographic imaging of the rock mass based on seismic wave propagation and collection of full microseismic waveforms to allow application of advanced seismic and statistical analysis techniques.Formerly with Mines Technical Services, Falconbridge Limited, Sudbury Operations, Falconbridge , Ont., P0M 1S0.Presented at the Fred Leighton Memorial Workshop on Mining Induced Seismicity, Montreal, Canada, August 30, 1987.     

Attenuation properties of viscoelastic material

The attenuation properties of eight rheological models have been studied theoretically. The expressions forQ have been obtained by using dissipated and stored energies and/or complex modulus for each model. The dependence ofQ on frequency has been demonstrated. The three-element elastic model appears to be the best one to represent the viscoelastic nature of the earth's material for a finite value ofQ.     

Evaluation of rainfall-runoff performance using the stochastic integral equation method

The stochastic integral equation method (S.I.E.M.) is used to evaluate the relative performance of a set of both calibrated and uncalibrated rainfall-runoff models with respect to prediction errors. The S.I.E.M. is also used to estimate confidence (prediction) interval values of a runoff criterion variable, given a prescribed rainfall-runoff model, and a similarity measure used to condition the storms that are utilized for model calibration purposes.Because of the increasing attention given to the issue of uncertainty in rainfall-runoff modeling estimates, the S.I.E.M. provides a promising tool for the hydrologist to consider in both research and design.