Comparison of damage data from questionnaires and field survey: the case of the June 20, 1978 Thessaloniki (northern Greece) M6.5 earthquake

The earthquake of June 20, 1978 (M6.5) near Thessaloniki, Greece, and the abundant information on damage distribution provided researchers with an opportunity for a more detailed study of earthquake effects. The damage on buildings caused by that earthquake was recorded in several ways. In this paper two of them will be presented and discussed: First, the use of questionnaires filled in by citizens and second, the in situ inspection of the buildings by a team of expert engineers, enriched by data of retrofitting costs, where available. In the current study, the damage data derived from the questionnaires are compared against the ones given by the engineers after they have been both converted to the European Macroseismic Scale 1998 (EMS-98) Damage Grades. It is observed that for EMS-98 damage grades equal and larger than 2 the questionnaire method overestimates damage while for lower grades both approaches provide comparable results.     

Experimental evidence of a unique flow rule of non-cohesive soils under high-cyclic loading

The presented results of cyclic triaxial tests on sand demonstrate that the cumulative effects due to small cycles obey a kind of flow rule. It mainly depends on the average stress ratio about which the cycles are performed. This so-called “cyclic flow rule” is unique and can be well approximated by flow rules for monotonic loading. Amongst others it is shown that the cyclic flow rule is only moderately influenced by the average mean pressure, by the strain loop (span, shape, polarization), the void ratio, the loading frequency, the static preloading and the grain size distribution curve. A slight increase of the compactive portion of the flow rule with increasing residual strain (due to the previous cycles) was observed. These experimental findings prove that the cyclic flow rule is an essential and indispensable concept in explicit (N-type) accumulation models.     

Ethnic residential shifts: The Greek population of Akron, Ohio, 1930–2005

The purpose of this paper is to apply the framework of transnationalism to the study of the Akron, Ohio Greek community through the spatio-temporal changes in the residential patterns. Church records for the period 1930 to 2005 form the basis of the study. The first Greek immigrants arrived in Akron, Ohio in the latter part of the nineteenth century and settled around the commercial zone in the central city. Additional immigrants, mostly young males with little education, arrived during the early decades of the twentieth century to seek employment in the growing industries, especially the tire factories. The establishment of a sizable colony made it possible to form a parish church in close proximity to the place of work. In addition to the place of worship, ethnic stores, and coffee houses became foci of ethnic life. Although this central city cluster was undergoing minor residential shifts to the suburbs, it was identifiable until the early 1970s. By then most of its immigrant residents as well as their American born children moved to the suburbs, especially in the northwestern part of the city, because of economic improvement. Post-1965 immigrants bypassed the central city cluster and settled in the suburbs. Anecdotal information suggests that these immigrants, individually and collectively as a group, maintain a variety of economic, social, and cultural connections with their place of origin as well as the Akron Greek community. Thus, transnationalism is an appropriate framework to study recent immigrants who maintain concurrent connections to the United States and Greece.     

Upper bound analysis of tunnel face stability in layered soils

The working face of tunnel constructions has to be kept stable during tunneling to prevent large soil deformations or fatal failure. In layered soils with lower cohesion, failures happen more often and more abrupt than in cohesive soils. Therefore, the maintenance of a proper support pressure at the tunnel working face is of high importance. In this paper, an upper bound analysis is introduced to investigate the minimum support pressure for the face stability in layered soils. A three-dimensional kinematically admissible mechanism for the upper bound analysis is improved to model potential failure within different soil layers. An analytical solution for the support pressure assessment is achieved. The influence of the crossing and cover soil on the face stability is analyzed, respectively. This solution provides an analytical estimation of the minimum support pressure for the face stability. It may be used as a reference for projects under similar conditions.     

Fast water infiltration: a mechanism for fracture formation during land subsidence

A mechanism for fracture generation and for triggering land subsidence is presented. Infiltration through a pre-existing fracture zone into a two-layered system, as well as the deformation of unconsolidated sediments on the land surface, was numerically investigated. The numerical simulation of infiltration is based on a two-phase flow-model concept for porous media, and for the deformation, it is based on a Mohr-Coulomb model concept. Different studies with variations of the fracture parameter and infiltration conditions have been carried out. The infiltration results show that fast infiltration in a partially saturated aquifer leads to land subsidence, extension of pre-existing fractured zones and the generation of new cracks. If the water column is only on the fracture, the clay layer acts like a barrier and inhibits the infiltration through the fracture. If the water column covers the entire surface, the barrier effect is overcome; the infiltration intensity depends on the height of the water column, the fracture permeability and the fracture width. The deformation results show that a strong rainfall event of 2 h leads to deformations that are about 30 % of the vertical and 70 % of the horizontal annual land-subsidence rates.     

The influence of the construction process on the deformation behaviour of diaphragm walls in soft clayey ground

Conventional numerical predictions of deep excavations normally neglect the construction process of the retaining structure and choose the earth pressure at rest as initial condition at the beginning of the simulation. The presented results of simulation and measurements during the construction process of the Taipei National Enterprise Center show, that such an assumption leads to an underestimation of the horizontal wall deflection, the surface ground settlements as well as the loading of the struts in case of normally to slightly over‐consolidated clayey soil deposits. The stepwise installation process of the individual diaphragm wall panels results in a substantial modification of the lateral effective stresses in the adjacent ground. Especially the pouring process of the panel and the fresh concrete pressure causes a partial mobilization of the passive earth pressure and a distinct stress level increase in the upper half of the wall. As a consequence of the increased stresses prior to the pit excavation, up to 15% greater ground and wall movements are predicted. Moreover, the increased stress level due to the installation process of the diaphragm wall leads to substantial higher strut loadings during the excavation of the pit. Copyright © 2006 John Wiley & Sons, Ltd.     

Quantifying FES2004 S<Subscript>2</Subscript> tidal model from multiple space-geodesy techniques,GPS and GRACE,over North West Australia

Unmodeled sub-daily ocean S₂ tide signals that alias into lower frequencies have been detected in the analysis of gravity recovery and climate experiment (GRACE) space gravity fields of GRGS. The most significant global S₂ aliased signal occurs off the northwest coast of Australia in a shallow continental shelf zone, a region with high tidal amplitudes at a period of 161 days. The GRACE S₂ aliased equivalent water height grids are convolved with Green’s functions to produce GRACE aliased tidal loading (GATL) vertical displacements. The analysis of hourly global positioning system (GPS) vertical coordinate estimates at permanent sites in the region confirms the presence of spectral power at the S₂ frequency when the same ocean tide model (FES2004) was used. Thus, deficiencies in the FES2004 ocean tide model are detected both directly and indirectly by the two independent space geodetic techniques. Through simulation, the admittance (ratio of amplitude of spurious long-wavelength output signal in the GRACE time-series to amplitude of unmodeled periodic signals) of the GRACE unmodeled S₂ tidal signals, aliased to a 161-day period, is found to have a global average close to 100%, although with substantial spatial variation. Comparing GATL with unmodeled S₂ tidal sub-daily signals in the vertical GPS time-series in the region of Broome in NW Australia suggests an admittance of 110–130%.     

Revision of the EU Bathing Water Directive: economic costs and benefits

The European Union (EU) Bathing Water Directive of 1976 ([Commission of the European Communities, 1976. Council Directive of 8th December 1975 Concerning the Quality of Bathing Water (76/160/EEC). Official Journal of the European Community. 5th February 1976, L31/1, Brussels]) sets out standards for designated bathing waters which should be complied with by all member states. Intervening advances in pollution science, related technology and managerial expertise have allowed the European Commission to consider revision of EU environmental legislation where appropriate. As a result, a number of revisions to the 1976 Directive have been proposed ([Commission of the European Communities, 1994. Commission Proposal for a Council Directive Concerning the Quality of Bathing Water. Communication from the Commission to the European Parliament and the Council, COM (94) 36 Final, Brussels; Commission of the European Communities, 2000. Developing a New Bathing Water Policy, Communication from the Commission to the European Parliament and the Council, COM (2000) 860 Final, 21/12/200, Brussels; Commission of the European Communities, 2002. Commission Proposal for a Directive of the European Parliament and of the Council Concerning the Quality of Bathing Water, COM (2002) 581 Final, 24/10/2002, Brussels]). This paper considers these revisions in terms of the economic costs and benefits associated with any change in policy. The focus is on the public's willingness to pay for a revised Directive and the consequent public health benefits afforded to individuals and society. These economic benefits are compared to the costs of implementing changes to bring bathing waters up to the required standard.