This study was based on the combination of simple and quick techniques to substitute the conventional manufacturing system assembly of metal truss connected by wood structures for free environments and less movement. Although simple in its use, the bolted connections are extremely complex in their analysis and behavior. The study was based on evaluating bolted wood/wood and wood/wood with a metal divider interface connections, just to observe the strength of the set's performance under real loads of support coming from the roof elements of the work. Load tests to evaluate the shear behavior nonlinear of the connecting bolts were carried out with loads until 10 ton. On prototypes previously dimensioned according to NBR 6120 to determination of the values of the loads, with two, three and four bolts of the type SAE J 429 grade 5. It was observed that the insertion of a metal plate between the pieces of wood increased by about 50% in the shear strength of the connection. The models A 1 and B 1 , with two bolts with or without plate, were the ones with least resistance, while with three bolts were most loads resisted. Simulations with FEMAP-Finite Element Modeling and Post-processing/NASTRAN were performed for comparison.
The oil and gas production has grown steadily, and the care with its transportation grid needs to be maintained and expanded. The pipeline used in the transport of gas and oil by-product requires materials with high mechanical strength, toughness, and fatigue resistance. The chemical composition and distribution, amount, and morphology of the final microconstituents of the steel are of paramount importance once it will directly influence the mechanical properties. The fracture toughness is one of the most important mechanical properties for the suitability of the steel for pipeline usage, and is most of the literature with pipelines study does not present tests such as crack tip opening displacement (CTOD), with a steady and controlled crack growth behavior, to evaluate its fracture toughness. This study compares the fracture toughness of the API 5L X70 steel between two plates of steel with different Nb content, 0.06 and 0.09 Nb wt.% by CTOD tests. The mechanical response was correlated to the grain size and distribution. The CTOD parameter was used to assess the fracture toughness at 25 °C and − 60 °C. The microstructures and microconstituents of the two plates of steel were similar. The matrices were composed of ferrite, with bands of secondary products, including degenerated pearlite. Results showed a prone to the formation of a bimodal microstructure, coarse and fine grains, due to the addition of Nb. High-Nb steel presented better fracture toughness than normal-Nb steel at low-temperature.
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