The cohesive frictional crack model applied to the analysis of the dam-foundation joint

The mechanical behaviour of dam-foundation joints plays a key role in concrete dam engineering since it is the weakest part of the structure and therefore the evolutionary crack process occurring along this joint determines the global load-bearing capacity. The reference volume involved in the above mentioned process is so large that it cannot be tested in a laboratory: structural analysis has to be carried on by numerical modelling. The use of the asymptotic expansions proposed by Karihaloo and Xiao at the tip of a crack with normal cohesion and Coulomb friction can overcome the numerical difficulties that appear in large scale problems when the Newton-Raphson procedure is applied to a set of equilibrium equations based on ordinary shape functions (Standard Finite Element Method). In this way it is possible to analyze problems with friction and crack propagation under the constant load induced by hydro-mechanical coupling. For each position of the fictitious crack tip, the condition K1=K2=0 allows us to obtain the external load level and the tangential stress at the tip. If the joint tangential strength is larger than the value obtained, the solution is acceptable, because the tensile strength is assumed negligible and the condition K1=0 is sufficient to cause the crack growth. Otherwise, the load level obtained can be considered as an overestimation of the critical value and a special form of contact problem has to be solved along the fictitious process zone. For the boundary condition analyzed (ICOLD benchmark on gravity dam model), after an initial increasing phase, the water lag remains almost constant and the maximum value of load carrying capacity is achieved when the water lag reaches its constant valu

Lifetime evaluation of concrete structures under sustained post-peak loading

Experimental tests on crack propagation in concrete under constant post-peak loading are simulated using the finite element method and the cohesive crack model, in both Mode I and Mixed-mode conditions. The time-dependent behaviour of concrete in the process zone is due to the interaction and growth of microcracks, a phenomenon which, for high constant load levels, turns out to be predominant over linear viscoelastic creep in the bulk material. In mechanical systems based on this type of material behaviour (creep and strain-softening taking place simultaneously), the initial value problem is non-parabolic, i.e., the error at one time level is affected by the accumulation of errors introduced at earlier time levels. Despite these difficulties, the scatter in numerical failure lifetime vs. load level turns out to be negligible in Mode I conditions and practically acceptable in Mixed-mode conditions. Therefore the time-dependent behaviour of the process zone can be inferred solely from the results of direct tensile tests

14th International Benchmark Workshop on Numerical Analysis of Dams

The Janneh dam is a 162-meter high Roller Compacted Concrete arch-gravity dam under construction in the Nahr Ibrahim Valley of Lebanon. The impounded reservoir will supply water, irrigate agricultural areas and generate hydropower . The dam will serve the Northern areas of Greater Beirut Mount Lebanon . The project site is located in high- seismicity region. The Peak Ground Accelerations are 0.37g and 0.51g respectively for OBE and SEE. Under favorable conditions (shape of the valley, strength of the bedrock, availability of construction materials), the construction of an arch-gravity dam is a more and more interesting alternative. The construction stages are simulated in ABAQUS environment in order to perform both linear and non-linear analyses

Fracture Mechanics Characterization of an AnisotropicGeomaterial

Argillites are considered worldwide as potential host rock for high level radioactive waste given the low permeability and strong adsorption potential. However, the excavation of the galleries of a repository would produce a disturbed zone around the boundaries rich of new fractures which may enhance the conductivity of the rock along the gallery axis. Several mine-by experiments have been performed in underground rock labs to investi- gate the features of the disturbed zone. In Mont Terri URL (Kanton Jura, Switzerland) the EZ-B experiment was specifically conceived for the measurement of excavation induced fractures around a small chamber. The host rock of the URL is a particularly compact and resistant argillite, known as the Opalinus Clay (OPA) excavated and OPA samples were subjected to fracture mechanics tests at the rock mechanics lab of IGAG-CNR in Torino, Italy. The tests aimed at the understanding aspects of the fracturing process occurring in OPA of Mont Terri, which may be considered a transversely isotropic geomaterial, whose planes of isotropy coincide with the beddin

Detachment of Plasters in Masonry Buildings: Analysis by Acoustic Emission and Numerical Simulation

An innovative laboratory procedure is described for testing the mechanical adhesion of new dehumidified mortars applied in the restoration works. A specific adherence test was carried out on composite specimens made by stone block and repair mortar. During the laboratory test the acoustic emission (AE) technique was employed, in order to estimate the amount of energy released from fracture propagation in the adherence surface between mortar and stone. A numerical simulation follows the experimental data. The evolution of detachment process of mortar in a coupled stone brick–mortar system was analysed by AE signals, which can improve the numerical model and predict the failure mode in the adhesion surface of repair plaster

A INTERDISCIPLINARIDADE NO PNE: A FORMAÇÃO DOCENTE

Law 13.005/2014 of the National Education Plan – PNE (2014-2024) marks and guides the Brazilian educational legislation, defining 10 guidelines and establishing 20 goals and strategies to be met throughout the decade, in all stages and modalities Basic Education and Higher Education. The PNE is a legal instrument that supports, as an educational policy, throughout the national territory, the rise in the interest of discussions on the professional valorization of teaching, at the municipal, state and district levels, which involves in the document adversities of educational aspects between they of teacher appreciation, curriculum and teacher training. And this article of bibliographic and documentary study aims to understand the concept of interdisciplinarity present in the PNE (2014 – 2024) and how these relations and propositional definitions in the goals and strategies for the support and implementation of policies aimed at teacher training in this perspective of interdisciplinarity in the school curriculum in the context of basic education. Keywords: Interdisciplinarity. Teacher training. National Education Plan.La Ley 13.005/2014 del Plan Nacional de Educación – PNE (2014-2024) marca y orienta la legislación educativa brasileña al definir 10 directrices y establecer 20 metas y estrategias a ser cumplidas a lo largo de la década, en todas las etapas y modalidades de Educación Básica y Educación más alta. El PNE es un instrumento jurídico que corrobora, como política educativa, en todo el territorio nacional, la valoración profesional de la profesión docente, a nivel municipal, estatal y distrital. Esto implica adversidades en aspectos de carácter educativo, especialmente en cuanto a la valoración de los docentes, el currículo y la formación docente. Este artigo de estudo bibliográfico e documental tem como objetivo apresentar o conceito de interdisciplinaridade presente no PNE (2014 – 2024) e suas relações e definições propositivas quanto às metas e estratégias para o amparo e implementação de políticas voltadas à formação docente articulada ao currículo escolar da Educación básica. Palabras clave: Interdisciplinariedad. Formación de profesores. Plan Nacional de Educación.A Lei 13.005/2014 do Plano Nacional de Educação – PNE (2014-2024) marca e orienta a legislação educacional brasileira ao definir 10 diretrizes e estabelecer 20 metas e estratégias a serem cumpridas ao longo do decênio, em todas as etapas e modalidades da Educação básica e do Ensino Superior. O PNE é um instrumento legal que corrobora, como política educacional, em todo o território nacional, a valorização profissional do magistério, em nível municipal, estadual e distrital. Isso envolve adversidades de aspectos de cunho educacional, em especial de valorização docente, currículo e formação docente. Este artigo de estudo bibliográfico e documental tem como objetivo apresentar o conceito de interdisciplinaridade presente no PNE (2014 – 2024) e suas relações e definições propositivas quanto às metas e estratégias para o amparo e implementação de políticas voltadas à formação docente articulada ao currículo escolar da educação básica. Palavras-chave: Interdisciplinaridade. Formação docente. Plano Nacional de Educação

Discutindo a Tendência Declinante da Taxa de Lucro em Marx

Discutindo a Tendência Declinante da Taxa de Lucro em Mar

Detachment analysis of dehumidified repair mortars applied to historical masonry walls

An innovative laboratory procedure for the pre-qualification of repair mortars is described. The tested mortars are suitable for use with new dehumidified plasters applied to historical masonry walls. Long-term plaster detachment frequently occurs because of the mechanical incompatibility of mortar. The procedure consists of the application of static loads to mixed stone block-mortar specimens with particular characteristics, in terms of geometry and adhesion at the interface. A numerical simulation based on the cohesive crack model was used to follow the experimental data, in order to describe the evolutionary phenomenon of detachment as a function of a small number of parameters. The methodology is currently being used at Sacro Monte di Varallo Special Natural Reserve (UNESCO heritage site) in Piedmont (Italy

Reply to Comment on Conopeptide-Functionalized Nanoparticles Selectively Antagonize Extrasynaptic N-Methyl-d-aspartate Receptors and Protect Hippocampal Neurons from Excitotoxicity In Vitro

In this manuscript, we provide precise answers to the concerns expressed by Molokanova et al. in their comment. In our reply, we highlight that there is indeed substantial agreement between our study and the one reported in Nano Letters by the Molokanova’s group.1 We believe this is a very important aspect because it proves the validity of the chosen approach, i.e. PEGylated AuNPs carrying NMDAR antagonists and with an overall dimension large enough to prevent their diffusion into the synapse can exclusively antagonize extrasynaptic NMDAR-mediated currents and are thereby neuroprotective