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[en] The aim of the recently completed European research program Meakado is therefore to study design options with requirements proportioned to the actual seismic context of constructions in areas characterized by a low or moderate seismic hazard, contrary to most researches aiming at maximizing the seismic performances. In this general framework, specific investigations have been carried out regarding typical beam profiles commonly used for multi-bay - multi-storey composite frames. In a first stage, experimental tests on class-3 composite beam-to-column connections were performed. The measurement results were evaluated with regard to the development of the hysteretic behavior with particular emphasis on the degradation. These test results have been used as reference for the calibration and validation of numerical model aiming at extending the scope of the experimental outcomes through appropriate parametric variations regarding the behavior of nodal connections as well as towards the global analysis and behavior of structures made of class 3 and 4 profiles. Numerical investigations of the global performance of composite frames with slender cross-sections are then performed resorting to the numerical model previously calibrated with respect to the experimental tests and additional simulations at node level. Results are compared to the performance of an equivalent frame made of compact steel profiles. Attention is paid to the effects of strength and stiffness degradation due to local buckling. The analysis of the results is specifically focusing on the comparison of the rotation capacity of the slender section with the actual rotation demand imposed by a moderate intensity earthquake. Based on the outcomes of these investigations, practical design recommendations are finally derived for multi-storey, multi-bay moment resisting frames with type b (full composite action) beam-to column connections located in low and moderate seismicity regions. (Author)
[en] In this paper the recording materials of seismic waves are listed and the problems of the accuracy of measuring of the coordinates and of the estimates of the energy parameters are discussed
[en] This paper analyzes the rose diagrams of the directions of 439 faults of the Variscian province, 476 faults of the Caledonian province, and 603 presently active faults of Tien Shan. It is shown that more than half of the faults of the Caledonian province of Tien Shan are a result of Late Paleozoic orogenesis, which spanned its entire territory. Our data indicate that seismic events of Tien Shan have resulted in no formation of new disjunctive dislocation in many cases exhibiting displacements along Paleozoic faults. This information should be taken into account during selection of building areas.
[en] Full text: CMP data resolution and wave pattern analysis has been conducted with objective to apply seismic stratigraphic interpretation for seismic survey conducted in the Central Hadramuta.Seismic data resolution is one of important implication while seismic stratigraphic interpretation.Wireline data derived from available wells (Gabrhood-1, Wadi Sana-1 Washa-1) have been compared to those of seismic sections shot across these wells with objective to determine seismic data resolution.Both Fresnel zone and wavelength dimensions have been verified through well velocity data.Elastic wave frequency range derived from those sections indicates that Central Hadramuta formations are characterized by frequency range around 40-70 Hz,which diminishes down to 10 Hz with depth.Velocities of intermediate formations between Fartag suite and basement have been averaged, with proper seismic attributes typical for respective formations were used to define seismic wavelength and Fresnel zone radii.Available data analysis indicates that seismic wavelength at the sequence top portion in Fartag suite (arrival time 0.3-0.6 ms) is around 35 m length, whereas it increases 10 times to achieve up to 350 m within carbonate formation (arrival time is over 1.6-1.7 ms).The adequate pattern has been observed for the Fresnel zone which radii amount to 170m and 1650-1700 m at the Fartag suite top and carbonate formation respectively.An attached figure shows that there is a systematic trend associated with Fresnel zone increment axcept of Gishen suite occurrence depth where velocity variation is insignificant within the terrigenous rocks.Analysis of consistent primaries derived from time-sections shot within Gabrhood, Wadi Sana and Washa areas indicate that variability of primary wavelets below the Fartaga horizon can be caused by the following factors:1.Wavelet signature change with offset due to incident angle increment as well as dependent on the stacking formation thickness relationship and investigation depth;2.Internal heterogeneity of the target horizons-heterogeneity dimension,faulting pattern and forth on;3.Change of incident pp pulse signature caused by unstable excitation and receiver site conditions;4.Subjective factors associated with geophysical signal analyst's skill used while processing.Each of these factors should be considered and studied separately,as some of them being taken into account and precluded would facilitate to improve seismic data quality and make seismic-stratigraphic interpretation easier.
[en] The present work investigates on the influence of small geometrical defects on the behavior of slender rigid blocks. A comprehensive experimental campaign was carried out on one of the shake tables of CEA/Saclay in France. The tested model was a massive steel block with standard manufacturing quality. Release, free oscillations tests as well as shake table tests revealed a non-negligible out-of-plane motion even in the case of apparently plane initial conditions or excitations. This motion exhibits a highly reproducible part for a short duration that was used to calibrate a numerical geometrically asymmetrical model. The stability of this model when subjected to 2 000 artificial seismic horizontal bidirectional signals was compared to the stability of a symmetrical one. This study showed that the geometrical imperfections slightly increase the rocking and overturning probabilities under bidirectional seismic excitations in a narrow range of peak ground acceleration. (authors)
[en] A minimum 1-D seismic velocity model for routine seismic event location purposes was determined for the area of the western Barents Sea, using a modified version of the VELEST code. The resulting model, BARENTS16, and corresponding station corrections were produced using data from stations at regional distances, the vast majority located in the periphery of the recorded seismic activity, due to the unfavorable land–sea distribution. Recorded seismicity is approached through the listings of a joint bulletin, resulting from the merging of several international and regional bulletins for the region, as well as additional parametric data from temporary deployments. We discuss the challenges posed by this extreme network-seismicity geometry in terms of velocity estimation resolution and result stability. Although the conditions do not facilitate the estimation of meaningful station corrections at the farthermost stations, and even well-resolved corrections do not have a convincing contribution, we show that the process can still converge to a stable velocity average for the crust and upper mantle, in good agreement with a priori information about the regional structure and geology, which reduces adequately errors in event location estimates.
[en] Radon can be transported effectively from deep layers of the Earth to the surface by carrier gases and by water. This transport is affected by phenomena accompanying seismic events. If radon is therefore monitored shortly before or during an earthquake, at a thermal water spring, an anomaly, i. e. a sudden increase or decrease in radon level, may be observed. Thermal springs and ground waters in Slovenia have therefore been systematically surveyed for radon. The work presented here is a continuation of our previous radon monitoring related to seismic activity carried out on weekly analyses during 1981-82 in thermal waters of the Ljubljana basin. In this paper, we focus on radon anomalies in thermal springs at Hotavlje and Bled in the period from October 2005 to September 2007
[en] The GNEMRE Dendro Tool provides a previously unrealized analysis capability in the field of nuclear explosion monitoring. Dendro Tool allows analysts to quickly and easily determine the similarity between seismic events using the waveform time-series for each of the events to compute cross-correlation values. Events can then be categorized into clusters of similar events. This analysis technique can be used to characterize historical archives of seismic events in order to determine many of the unique sources that are present. In addition, the source of any new events can be quickly identified simply by comparing the new event to the historical set