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Seismic safety evaluations of existing nuclear facilities are usually based on the assumption of structural linearity. For the design basis earthquake (DBE), it is reasonable to apply a conventional evaluation of the seismic safety of building structures and carry out a linear elastic analysis to assess the load effects on structural elements. Estimating the seismic capacity of a structural element requires an estimation of the critical combination of responses acting in this structural element and compare this combination with the capacity of the element. By exploiting the response-spectrum-based procedure for predicting the response envelopes in linear structures formulated by Menun and Der Kiureghian (2000a), algorithms are developed for the seismic margin assessment of reinforced concrete shell finite elements. These algorithms facilitate the comparison of the response-spectrum-based envelopes to prescribed capacity surfaces for the purpose of assessing the safety margin of this kind of structures. The practical application of elliptical response envelopes in case of shell finite elements is based on the use of layer models such as those developed by Marti (1990), which transfer the generalized stress field to three layers under the assumption that the two outer layers carry membrane forces and the internal layer carries only the out-of-plane shears. The utility of the assessment approach is discussed with reference to a case study of a 3D structure made of reinforced concrete walls. International audience

Longgupo cave, located in Chongqing Municipality, China, was discovered in 1984. Sixteen Gigantopithecus teeth and two hominid fossils accompanied with abundant mammalian fossils and stone artifacts were unearthed from the site. Previous dating result is questioned because of the complexity of deposition history. In this study, seventeen mammalian fossil teeth collected from different layers of unit C II and C III (C III') during the 2003-2006 Sino-Franco joint excavation were analyzed by combined ESR and U-series methods, and calculated with a US-ESR model. In situ dose rates were remeasured in detail in 2012, in order to refine the external dose rate determination. Uranium-series analyses indicate that no obvious uranium leaching has occurred, and all the teeth underwent a very recent uranium uptake history, except one from layer C III 3 of the south wall. The US-ESR results show that the ages of ten teeth from unit C III' of the north wall are consistent in general, about 2.35 Ma. The ages of seven samples from south wall are not in accordance with the stratigraphic order: three teeth are much younger than the other four, probably attributed to the relative higher uranium concentration and U/Th ratio in the dental tissues and significant higher in situ gamma dose rate. Nevertheless, the three teeth from C III of the south wall give an average age of - 2.48 Ma. The fossil ages obtained in this work combined with paleontological evidence and new paleomagnetic results place Longgupo at the very beginning of the Early Pleistocene. Compared with other early hominid settlements, Longgupo is one of the earliest evidences of hominid settlement in China and East Asia to date. International audience

We probe magnetic domain walls in cylindrical soft magnetic nanowires using electron holography. We detail the modelling of expected contrast for both transverse and Bloch point domain walls and provide comparison with experimental observations performed on NiCo nanowires, involving also both magnetic and electrostatic contribution to the electron holography map. This allows the fast determination of the domain wall type without the need for uneasy and time-consuming experimental removal of the electrostatic contribution. Finally, we describe and implement a new efficient algorithm for calculating the magnetic contrast. International audience 3 pages, 2 figures

International audience