The object of this research is to develop a model for the calibration of prefabricated timber wall frames (PTWFs) with dimension of 244 by 244 cm (width by height) respectively made of Gmelina arborea Roxb. and Hieronyma alchorneoides Allemão wood and two types of fastener (nails and screws). The PTWFs were submitted to a lateral load test and the vertical and horizontal displacement, maximum load (P m), strength, stiffness values and mode of failure were determined. Results showed a greater failure percentage in the joint between the central stud and the top and bottom plates for both species and both fastener types used. PTWFs made of H. alchorneoides timber using screws showed greater values than PTWFs made of G. arborea for load at the proportionality limit and maximum load. Finally, computational model showed that the highest calibration percentage was achieved in the vertical orientation in PTWFs made using nails in both species. Meanwhile, PTWFs using screws showed calibration percentages of 58.0 and 43.5 %. The highest calibration percentage of 89.9 % was recorded in G. arborea PTWFs joined with nails, whereas the lowest calibration percentage of 69.4 % was recorded in H. alchorneoides PTWFs joined with screws.
The objective of this study was to characterize the performance of composite wood blocks (CWB) by testing internal bonding, nail extraction resistance, and water absorption. The CWB were glued with two wood adhesives, polyvinyl acetate (PVAc), and urea formaldehyde (UF), modified with 1% nanocrystalline cellulose (NCC). Three tropical species were employed: Vochysia ferruginea, Cordia alliodora, and Gmelina arborea. In addition, the original European pallet in the static flexure test was evaluated. The results showed that the internal bonding relative to solid wood blocks (SWB) increased with both adhesives. Meanwhile, the CWB of V. ferruginea with UF and C. alliodora with PVAc showed the greatest resistance to nail extraction, while in G. arborea, the NCC increased the resistance to nail extraction. The CWB with modified adhesives absorbed more moisture, particularly with PVAc, compared with the SWB. In static flexure tests of the pallets fabricated with CWB, the load at the limit of proportionality and the maximum load increased, while deflections were lower, compared with SWB. The results showed the potential of utilizing NCC in CWB fabricated with tropical species.
El artículo presenta algunos de los resultados generales del Proyecto de Extensión: Priorización de Estructuras de Puentes Utilizando Indicadores de Desempeño: Plan Piloto Municipalidad de El Guarco, este proyecto se ejecutó entre enero 2018 a diciembre 2019, por parte del Instituto Tecnológico de Costa Rica. Se muestra en el artículo la importancia de contar con herramientas para priorizar las intervenciones a realizar sobre un grupo de puentes y se describe la metodología utilizada para dicha priorización.
La metodología propuesta se basa en el uso de 3 indicadores estratégicos: BCI, VAM y USO, definidos como indicadores técnicos, complementando este cálculo con un indicador socioeconómico, para tener finalmente una lista de intervenciones priorizada de forma integral.
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