Abstract The efficiency of steel fibers for shear strength of reinforced concrete beams is assessed. Four beams were evaluated: control consisted of one beam without any steel fibers and three beams with reinforced concrete with steel fibers. All beams were reinforced for shear strength by a minimum reinforcement rate. The influence of fiber content added to concrete, at 0.5%, 0.8% and 1.0%, and the possibility of partial or total replacement of conventional shear reinforcement (stirrups) by steel fibers were evaluated. Results showed a significant increase in ductility and stiffness of the beams with steel fibers and, consequently, changes in the failure mode were observed, of shear (control beam) to flexure behavior (beams with steel fibers).

A demanda por informações silviculturais de espécies florestais alternativas para reflorestamentos com fins econômicos, entre as quais incluem os métodos de produção de mudas, tem aumentado nos últimos anos. Neste trabalho, avaliou-se a influência de volumes de tubetes, com dimensões de 115, 180 e de 280 cm³, no crescimento de mudas de guanandi (Calophyllum brasiliense Cambess.) e cedro-australiano (Toona ciliata M. Roem. var. australis (F. Muell.) Bahadur). O substrato utilizado foi composto por uma mistura de 80% de substrato comercial e 20% de argila. Foram avaliados o diâmetro de colo e a altura das mudas aos 60, 90, 120 e 150 dias após a repicagem. Nessa última ocasião, determinou-se também o peso de massa seca da parte aérea, do sistema radicular e total, bem como o Índice de Qualidade de Dickson. Houve efeito do volume do tubete sobre as características das mudas, sendo o cedro-australiano a espécie mais responsiva. Conclui-se que para o guanandi o tubete mais indicado é o de 180 cm³ e para o cedro-australiano, o de 280 cm³.

The search for silvicultural information, including the seedling production methods, about alternative forest tree species for forestry with economic purposes have increased in the last years. In this work, the influence of the volume of tubes at sizes of 115, 180 and 280 cm³, on the growth of seedlings of Guanandi (Calophyllum brasiliense Cambess.) and Australian Cedar (Toona ciliata M. Roem. var. australis (F. Muell.)) was evaluated. The substrate used was composed by mixture of 80% of commercial substrate and 20% of clay. The collar diameter and the height of the seedlings were evaluated at 60, 90, 120 and 150 days after transplantation. In the last mensuration the dry weight of the aerial plant, of the root system and the total weight, and the Quality Index of Dickson were also determined. There was an effect of the tube volume on the growth and the quality of the seedlings, and the reaction of the Australian Cedar was greater. It was concluded the, for the Guanandi, the best tube is that of 180 cm³ and for the Australian Cedar is the tube of 280 cm³.