Tiago Hendrigo de Almeida

A Catalog of Candidate Field Horizontal-Branch and A-Type Stars. III. A 2MASS-Cleaned Version

We present coordinates and available photometric information (either from previous or recent broadband UBV observations, and near-infrared photometry from the 2MASS Point Source Catalog) for 12,056 stars (11,516 of which are unique) identified in the HK Survey of Beers and colleagues as candidate field horizontal-branch or A-type stars. These stars, in the apparent magnitude range 10 ≤ B ≤ 16.0, were selected using an objective-prism/interference-filter survey technique. The availability of 2MASS information permits assembly of a cleaned version of this catalog, comprising likely blue horizontal-branch (BHB) stars or blue stragglers in the color interval [-0.2 ≤ (B - V)0 ≤ +0.2], which are of particular interest for investigation of the structure, kinematics, and dynamics of the thick disk and inner halo of the Milky Way, the total mass and mass profile of the Galaxy, and as potential foreground/background objects in efforts to bracket distances to high-velocity clouds of H I. A comparison of the stars classified as high-likelihood BHB candidates with previous classifications based on UBV photometry and medium-resolution spectroscopy indicates that this class contains 78% correct identifications.

Avaliação das estruturas de cobertura em madeira de um galpão de estoque de produtos químicos

Este trabalho tem com objetivo avaliar a integridade das estruturas que fazem parte da cobertura de um galpao de 70 anos, destinado ao estoque de produtos quimicos, localizada no Estado de Sao Paulo (Brasil), e apontar possiveis solucoes para os problemas identificados. Buscou-se estimar a influencia dos residuos dos produtos quimicos depositados nas superficies dos elementos estruturais e identificar a especie de madeira utilizada no projeto, por meio de ensaios fisicos (densidade aparente) e mecânicos (compressao e cisalhamento paralelo as fibras. Os problemas identificados foram: (a) umidade devido a telhas quebradas; (b) deterioracao superficial da madeira em funcao de reacao quimica entre os produtos armazenados e a estrutura; (c) cavilhas de madeira com instalacao incompleta; (d) falta de maos-francesas em algumas tercas; (e) travamento inadequado das trelicas; e (f) deterioracao de pregos de fixacao por oxidacao. Pelas observacoes realizadas, as solucoes indicadas sao de facil execucao, pois as estruturas nao foram severamente prejudicadas. Com relacao a especie de madeira, os resultados das propriedades mecânicas obtidas associadas a densidade aparente apontaram para a especie Peroba-Rosa ( Aspidosperma polyneuron ). A analise estatistica de resultados apontou para a nao influencia do produto quimico no desempenho da estrutura do telhado.

Modulus of Elasticity of Schizolobium amazonicum Wood Evaluated by Transversal Vibration Technique

Schizolobium amazonicum is being much used in Brazil for several purposes because, besides being a native Brazilian wood specie, has important features such as low density and small incidence of natural defects. At this point, researches with the purpose of obtaining further knowledge of their properties are being conducted to better targeting their use. The aim of this research is to evaluate the modulus of elasticity of structural size pieces of Schizolobium amazonicum wood using the technique of transverse vibration. Tests were carried out using 30 pieces (standard moisture content 12%) with sizes of 3 cm x 15 cm x 2.5 m. The average value of elastic modulus determined for lumber of Schizolobium amazonicum was interesting to its low specific gravity.

Hardness of the Schizolobium amazonicum Wood

Brazil has an infinity of native species that provide wood with good properties for use in civil engineering, industries and other segments. Schizolobium amazonicum Wood is a species that is much used in Brazil to manufacture of wood based-products. Researches regarding the properties are being performed in order to rationalize their use. The aim of this research is to determine the hardness of the Schizolobium amazonicum Wood in directions parallel and normal to the grains. The tests occurred in accordance with the Brazilian Code ABNT NBR 7190: 1997. The average values determined were interesting hardness upon the low specific gravity presented by Schizolobium amazonicum Wood.

Stress Distribution in Tauari Wood Beam

Wood is widely used in many sectors of civil construction as a structural material. Brazilian code ABNT NBR 7190:1997 Design of Timber Structures governs the method of project design as well as the characterization of wood for structural design. In this aspect the code considers wood as an orthoptic material, however is well known that the organic origin provides great anatomical complexity to its. This work aims to study the distribution of normal stresses in a Tauari wood beam subjected to the elastic regime, and to ascertain the current position of the Neutral Line during test. For this purpose, a four-point static bending test and subsequent compression and tension to the grain tests were performed to determine the modulus of elasticity and calculate the normal stresses by recording deformations and applying Hookes Law. The data were statistically analyzed to define bests adjusts to Stress vs. Strain diagrams, and thus determine the location of the Neutral Line. It was verified that the position of the Neutral Line was a normal distribution variable, being located at 1,07cm above the geometric center of the board. Finally, the comparison between values of normal tension obtained experimentally and through the theoretical method was determined and similarities were verified in these data, being also plausible the theory for the calculation of the normal tensions of the wood beams, when it is in the elastic regime.

Forces in Bracing Elements of Timber Trusses

This book deals with the analysis of the forces acting in bracing of triangular timber trusses of warehouses roofings by computational numerical models based on the Finite Element Method (FEM). Were used the structural analysis software STRAP and consider the operation of bracing in the three-dimensional structure. The maximum force values obtained in the three-dimensional models were compared to the minimum values indicated by the estimation method of the Brazilian standard ABNT NBR 7190:1997, which is based on the lateral instability of the braced element. The values of three-dimensional models are also compared to the methods of Eurocode 5, the South African Standard SABS 0163 and the values proposed by UNDERWOOD (2000), by presenting a similar formulation to the NBR 7190:1997. The models represent usual warehouses with dimensions ranging from 12, 18 and 24 meters wide, 24, 48 and 96 meters length, and 3, 4 and 6 meters column heights. In this context, were analyzed the trusses types: Pratt and Howe, the timber classes: C30 and C50 and the roof types: fiber cement, metal sheets and ceramics tiles – materials most used in Brazil.

Compression Strength of Brazilian Exotics Wood Species Perpendicular to the Grain

Wood is a natural material that present variability of their properties. When used as ties in railways or as bridges decks, wood is request with compressive loads in direction perpendicular to the grain. The aim of this research is determining the compressive perpendicular to the grain strength (fc90) of two Brazilian exotic wood species. Tests were carried out using wood of Corymbia (Corymbia citriodora) and Pinus (Pinus taeda L.). Specimens and test methods were realizes according to Brazilian Standard Code ABNT NBR 7190:1997 (specimens at 12% of moisture content). Compressive perpendicular to the grain strength values to Corymbia and Pinus were equal to 17.00 MPa and 3.60 MPa, respectively. More studies about mechanical and physical properties of wood is important to rationalize their uses and provide greater knowledge about this material.

Embedment Parallel to the Grain Strength of the Schizolobium amazonicum Herb Wood Specie

Wood is one of the main raw materials used by man in several uses. It can be used in furniture and package industries, and also in components for building construction. For all these purposes, it is necessary to know the physical and mechanical properties of wood specie being used. Brazilian Code ABNT NBR 7190:1997, in its Annex B, presents methods for determining wood mechanical properties, among them the embedment parallel to grain. This property is important because it relates to the design of bolted and nailed joints in timber structures. This research aims to the experimental determination of embedment strength parallel to grain strength for Schizolobium amazonicum Herb, a wood specie recently used for structural purposes. Results showed that embedment strength for Schizolobium amazonicum Herb wood specie is lower when compared with traditional tropical essences, but sufficient for some structural applications.