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This article describes the research carried out to assess the efficiency and mechanical performance of aluminum alloys to be used in the production of hysteretic dissipative brace devices for the seismic protection of old reinforced concrete buildings. Two different standard aluminum alloys were considered: the 6082 and the 5083 alloys, supplied with the T6 and H111 tempers, respectively. Features such as the inelastic deformation capacity and energy dissipation under cyclic loading were evaluated from experimental results and several performance indexes were computed. Additionally, four heat treatments (tempers) were applied to the 6082 alloy, namely: two tempers considering solubilization followed by two different aging cycles (AG); and two tempers considering two different annealing treatments (AN). The influence of these tempers on the mechanical behavior of the 6082 alloy was assessed through monotonic tensile and cyclic tension-compression tests. The results and discussion about the mechanical performance of each of the tested alloys and tempers are also presented. A comparative analysis between mechanical performance of the standard alloys and the tempered 6082 alloys demonstrates the potential benefits induced by these tempers. The 6082 alloy annealed at 350 °C for 120 min (6082-AN350/120) has proved to be a promising solution in terms of its damage capacity and energy dissipation, representing a cost-effective solution in the production of extruded profiles with non conventional cross sections.

The seismic safety assessment of large concrete dams remains a significant challenge in dam engineering, as it requires appropriate analysis methods, modern performance criteria, and advanced numerical models to simulate the dam seismic behavior. This paper presents a method for seismic safety assessment of arch dams based on Endurance Time Analysis (ETA), using tensile and compressive damage results from a robust formulation for seismic analysis considering joint opening/sliding and concrete non-linear behavior (finite element program DamDySSA, under development in LNEC). The seismic performance is evaluated by controlling the evolution of the damage state of the dam, according to predefined performance criteria, to estimate acceleration endurance limits for tensile and compressive damage. These acceleration limits are compared, respectively, with the peak ground accelerations prescribed for the Operating Basis Earthquake (OBE) and Safety Evaluation Earthquake (SEE), aiming to evaluate the dam seismic performance relative to both earthquake levels efficiently, using a single intensifying acceleration time history. The ETA-based method is applied to the cases of Cabril Dam (132 m-high) and Cahora Bassa Dam (170 m-high), confirming its usefulness for future seismic safety studies, while the potential of DamDySSA for non-linear seismic analysis of arch dams is highlighted.

The indirect identification of doping in sports can be performed by assessing athletesʼ hematological perturbations from the analysis of blood collected on different occasions. Because prosecution for doping based on this information requires expensive and time-consuming interpretation of blood analysis results by various expert hematologists, mathematical data screening is performed to decide which cases should be forwarded to hematologists. The current Bayesian and univariate screening of data does not process the multivariate trends of blood parameters or take the time interval between samplings into account. This work presents a computational tool that overcomes these limitations by calculating a single score, the hematological perturbation index (HPIx), for which a threshold is defined above which hematologists should be asked to assess the athleteʼs biological passport. The doping detection from this index, normalized for days difference between samplings based on 3, 4 or 5 consecutive samplings, is associated with true positive result rates (TP) not below 98% and false positive result rates (FP) less than 0.9%. Therefore, this tool can be useful as an early warning system of hematological perturbations to decide which athletes should be more closely monitored and which biological passports should be forwarded to hematologists for medical interpretation of data.

Over the past decade, monitoring systems for Seismic and Structural Health Monitoring (SSHM) have been assuming a greater role in the safety control of large concrete dams. In this article, the dynamic behavior of two large arch dams equipped with SSHM systems is analyzed, in order to present some of the main theoretical, computational and practical innovations developed recently for the improvement of large dams’ continuous dynamic monitoring using SSHM systems. The case studies are two large arch dams that have been under continuous dynamic monitoring over the last ten years: Cabril dam (132 m high), the highest dam in Portugal, and Cahora Bassa dam (170 m high), located in Mozambique, one of the highest dams in Africa. The Seismic and Structural Health Monitoring (SSHM) systems installed in both dams have similar schemes and were designed to continuously record acceleration time series in several locations at the upper part of the dam body and near the dam-foundation interface, using uniaxial and triaxial accelerometers. Specific software was developed for monitoring data analysis, including automatic modal identification, to obtain natural frequencies and mode shapes, for automatic detection of vibrations induced by seismic events, to be distinguished by those caused by other operational sources, and for comparison between results retrieved from measured vibrations and numerical results obtained from computational 3DFE models. The numerical analyses are carried out using a 3DFE program for linear and non-linear dynamic analysis of concrete dams, based on a solid-fluid coupled formulation to simulate the dam-reservoir-foundation system, considering the dam-water dynamic interaction and the propagation of pressure waves throughout the reservoir. The most significant experimental results from continuous dynamic monitoring are presented for Cabril dam and Cahora Bassa dam and compared with numerical results, with emphasis on the evolution of natural frequencies over time, on vibration mode shapes for various water levels, and, finally, on the measured accelerations during seismic events. Furthermore, the main results of non-linear seismic response simulations, considering joint movements and concrete damage, are also presented for both dams in order to assess their seismic performance, using an intensifying seismic accelerogram prepared for Endurance Time Analysis.

This paper focuses on presenting a complete study on the dynamic behavior of Cahora Bassa dam (Mozambique), a 170 m high double curvature arch dam which has been under continuous vibrations monitoring since 2010. The installed Seismic and Structural Health Monitoring system was designed to continuously record acceleration time series in several locations in the dam body (crest gallery) and near the dam-rock interface, under ambient/operational vibrations and during seismic events, using uniaxial and triaxial accelerometers. The system was complemented with the development of software for automatic modal identification and automatic detection of seismic vibrations. The numerical simulations are carried out using a 3D finite element program, based on a solid-fluid coupled formulation to simulate the dam-reservoir-foundation system, considering dam-water dynamic interaction and propagation of pressure waves throughout the reservoir. The main experimental outputs are presented and compared with results from 3D finite element analysis, including the evolution of identified natural frequencies over time, vibration mode shapes, and the seismic response in accelerations. Finally the non-linear seismic behavior of Cahora Bassa dam is studied for an input accelerogram with a 0.6 g peak acceleration, considering the joints movements and a damage model for concrete.

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This article presents the results of an extensive experimental programme investigating the structural performance for in-plane loads of old masonry walls strengthened using a specific technique that consisted of applying a CFRP mesh embedded within a shotcreted render. In this article the expression old masonry refers to rubble stone masonry with lime-based mortar but it is believed that the strengthening technique can also be applied to other types of old masonry (e.g. solid or almost solid clay or concrete brick masonry). The reinforcing composite material, called CFRP reinforced render (CFRP-RR), is characterized by the use of a CFRP mesh and the shotcreted pre-mixed mortar, lime-based, specific for the rehabilitation of old masonry load bearing walls. This material is applied to one or both faces of the masonry walls, thus improving both the in-plane and out-of-plane behaviour for horizontal loads (the latter benefits are described in Ref. [ 1 ]). The experimental programme consisted of the in-plane testing of full-scale physical models of walls, herewith called specimens. These were subjected to reversed cyclic horizontal loads (simulating earthquake loads) with constant vertical loads (simulating gravity loads). The comparison between the experimental results of the non-reinforced with the reinforced (strengthened) specimens allowed the quantification of the inherent benefits in terms of structural performance under earthquake actions.

This article describes the initial development stages of a structural window frame system for the in-plane seismic strengthening of load-bearing masonry wall buildings. The solution implemented ult...

This work proposes an approach to automatically parse children’s reading of sentences by detecting word pronunciations and extra content, and to classify words as correctly or incorrectly pronounced. This approach can be directly helpful for automatic assessment of reading level or for automatic reading tutors, where a correct reading must be identified. We propose a first segmentation stage to locate candidate word pronunciations based on allowing repetitions and false starts of a word’s syllables. A decoding grammar based solely on syllables allows silence to appear during a word pronunciation. At a second stage, word candidates are classified as mispronounced or not. The feature that best classifies mispronunciations is found to be the log-likelihood ratio between a free phone loop and a word spotting model in the very close vicinity of the candidate segmentation. Additional features are combined in multi-feature models to further improve classification, including: normalizations of the log-likelihood ratio, derivations from phone likelihoods, and Levenshtein distances between the correct pronunciation and recognized phonemes through two phoneme recognition approaches. Results show that most extra events were detected (close to 2% word error rate achieved) and that using automatic segmentation for mispronunciation classification approaches the performance of manual segmentation. Although the log-likelihood ratio from a spotting approach is already a good metric to classify word pronunciations, the combination of additional features provides a relative reduction of the miss rate of 18% (from 34.03% to 27.79% using manual segmentation and from 35.58% to 29.35% using automatic segmentation, at constant 5% false alarm rate). info:eu-repo/semantics/publishedVersion

This paper presents part of the results of an experimental campaign for the development of a strengthening technique, aimed at retrofitting old buildings by the application of exterior reinforcing render layers to their masonry walls. The experimental campaign comprised tests with out-of-plane loading on both strengthened and non-strengthened masonry walls. The strengthening layer material, hereby designated as CFRP (Carbon Fibre Reinforced Polymer) reinforcing render, is an innovative material for the seismic retrofitting of masonry walls. The reinforcing render material consists of a lime-based mortar reinforced with a carbon fibre mesh, applied on one or both facings of a masonry wall. This solution was developed to provide the masonry wall with improved mechanical properties, while respecting the main principles for a proper rehabilitation of old buildings.

This paper presents part of the results of an experimental study undertaken to develop a structural strengthening technique for old masonry buildings. The technique consisted of external reinforcement with a CFRP (Carbon Fibre Reinforced Polymer) reinforced render. CFRP reinforced render is an innovative seismic structural strengthening material for the structural masonry walls of old buildings. It consists of a non-cementitious mortar reinforced with a carbon fibre mesh and is applied to one or both wall faces (preferably by shotcreting). The reinforced render material was developed to improve the mechanical capabilities of masonry walls subjected to “in-plane” and “out-of-plane” seismic loads. Similarly to other widely known composite materials (e.g., reinforced concrete) the composite behaviour of the reinforced masonry relies on both the anchoring as well as on the adhesion of the reinforcing material to the masonry substrate. These aspects are the main objectives of the presented experimental work. The tests carried out in this study included the mechanical characterisation of all the materials involved, specifically of the mechanical behaviour of the reinforced composite render material, and finally focused on the bonding characteristics between CFRP reinforced render strips and masonry substrates, as well as the anchoring solution for the ends of the strips. The present experimental work is part of a research project to develop an innovative seismic strengthening technique for load-bearing masonry wall buildings.

The following paper presents the most recent results of a research programme carried out to, among other purposes, develop an innovative anchoring system for old masonry buildings. Despite the recognized importance of connections and anchoring systems, there is little experimental information about their strength and stiffness when installed in the masonry walls of old buildings. Therefore, one of the important goals of the research programme mentioned was the experimental characterization of the proposed anchoring system. The main characteristic of the proposed system, which makes it different from others, is an internal spherical steel element where the rod is connected. This steel eleme nt, called hinge, allows no orthogonality between the steel anchor plate and the tie rod, which makes it suitable for uneven connections between orthogonal walls and/or walls and floors. Besides this particular characteristic, the proposed system demonstrates all the capabilities of the traditional anchoring systems, namely, it can be used to strengthen the connection between orthogonal masonry walls or to ensure the connection of constructive elements (floors, roofs, stairs, etc.) to masonry walls. Moreover, numerical simulations with non-linear finite elements models were performed, aimed at reproducing the experimental tests for other load conditions or different wall thicknesses. The prime objective of the experimental and numerical studies was to assess the actual behaviour of the anchoring system and to establish appropriate design rules, which are also presented in this paper.

The present paper aims to contribute to the knowledge concerning the seismic assessment of load bearing masonry buildings with reinforced concrete slabs. The final goal of the present research was to propose a simple, yet accurate, methodology to assess the seismic safety of existing masonry buildings. The methodology here presented was based on the so-called ICIST/ACSS methodology with major improvements such as the extension to load bearing masonry wall buildings and the consideration of the effects of one of the most common strengthening solutions for masonry walls, here referred to as reinforced plastering mortar, as well as the possibility of considering four levels of increasing refinement: global, by alignment, by wall panel and by wall element. An extended research was performed on the existing methodologies to evaluate the seismic structural risk of load bearing masonry buildings, briefly describing methodologies similar to the one proposed, namely all of those that have in common the fact that they are based in the physical comparison between the resisting and acting shear forces at all storeys and along the two orthogonal horizontal directions. A case study is presented to check the applicability of the proposed methodology. The case study showed that the proposed methodology is relatively simple to apply and has a sufficiently good accuracy when compared with alternative methodologies. The degree of refinement of the analysis (global, by alignment, by wall panel and by wall element) must be taken into consideration and successively more complex analyses may be required when the results of simpler analyses are inconclusive.