Humberto C. Lima Júnior

Vigas mistas de madeira de reflorestamento e bambu laminado colado: análise teórica e experimental

This paper presents and discusses the experimental and theoretical analyses of layer composite beams of wood strengthened with bamboo. For this, the mechanical behavior of five composite beams and two wood beams was studied. The beams stuffing was composed of Pinus elliottii and the reinforcement of bamboo Dendrocalamus giganteus. The bamboo reinforcement was placed on the top and at the bottom of the beams. Different thicknesses of reinforcement were investigated. Curves of load vs. displacement and load vs. strain are presented. An increase of 50% was observed in the stiffness, when the composite beams are compared with the wood one. Finally, a numerical study was carried out applying the finite element method and a good agreement was observed between the theoretical and experimental values.

Resistência à compressão do solo-cimento com substituição parcial do cimento Portland por resíduo cerâmico moído

Neste trabalho, apresenta-se o estudo experimental da resistencia a compressao do solo-cimento, com substituicao parcial do cimento Portland por residuo cerâmico moido. Para tanto, foram ensaiados 81 especimenes cilindricos desse material a compressao, em que parte do cimento foi substituida por material cerâmico moido. Realizou-se uma programacao fatorial, na qual tres variaveis foram selecionadas para estudo: o teor de material ligante (cimento + residuo cerâmico), a umidade do solo e o teor de residuo cerâmico adicionado. E apresentado um estudo estatistico atraves de analise de variância da massa especifica do material e da resistencia a compressao. Tal estudo permitiu concluir-se que substituicoes de 25 e 57% do teor de cimento por material cerâmico podem produzir blocos de solo-cimento com resistencias superiores a 2 MPa, com teor de material ligante de 6 e 8%, respectivamente.

Determinação da tensão de aderência do bambu-concreto

This paper presents and discusses a study about the bamboo-concrete bond stress. Based on a statistical design of experiment, the investigation was divided in two steps: the first one, where the effects of the concrete compressive strength and the dimensions of the bamboo-splint cross-section were investigated; and the second, where the effect of artificial pins studding in the bamboo splints were evaluated. In both steps, ten replicates for each factor combination were done, resulting in 159 push-out tests. Bond stress versus relative displacement curves were presented and discussed. In addition, the design bond stresses of bamboo-concrete were calculated and their values were compared with those specified by International Building Codes for smooth steel and concrete. In the first step, it was observed that only the concrete compressive strength influences the bamboo-concrete bond stress and that, this stress is only 20% inferior to the smooth steel-concrete bond stress. In the second step, it was verified that bamboo and steel pins increased the transfer stress capacity between the concrete and bamboo.

Structural behavior of load bearing brick walls of soil-cement with the addition of ground ceramic waste

An experimental study of three load bearing walls is presented and discussed in this paper. The walls were of soil-cement bricks made with three different material proportions, in which two of them had part of the cement amount replaced by crushed ceramic waste. The walls were 95.20 cm high, 75.32 cm wide and 12.56 cm thick and had their bricks layered with cement paste. The walls were tested under compression and their displacements were measured with 5 dial gages. The walls had satisfactory behaviour and their strengths were suitable as required by Brazilian popular houses. The differences between the brick strength and the wall strength were less than 20%. A finite element analysis (FEA) was performed and the uniformity of the compressive stress distributions in the walls was evaluated. Finally, it was observed that the partial replacement of the cement by crushed ceramic waste is possible.

Mechanical analysis of hybrid bamboo-concrete columns

O objetivo deste trabalho foi avaliar o comportamento de pilares de bambu da especie Dendrocalamus giganteus com e sem o preenchimento interior de concreto. Foram ensaiados, a compressao axial, 18 pilares com comprimentos de 1, 1,5 e 2 m e, para cada comprimento, tal como 6 pilares, sendo 3 mistos de bambu-concreto e 3 formados apenas por colmos de bambu. Os resultados foram analisados atraves da teoria da instabilidade de casca cilindrica e das propriedades mecânicas dos materiais. Curvas forca vs. deformacao, teoricas e experimentais, sao apresentadas e a influencia do comprimento dos pilares sobre as ultimas forcas resistentes foi avaliada por meio de analise de variância. Os pilares mistos bambu-concreto apresentaram comportamento nao-linear e, em media, suas ultimas forcas resistentes mostraram valor da ordem de 50% da obtida pela Teoria da Resistencia dos Materiais; ja os pilares formados apenas por colmos de bambu, indicaram comportamento linear e suas ultimas forcas diferiram apenas 5% das teoricas, calculadas pela Teoria da Resistencia dos Materiais. Verifica-se que a utilizacao de pilares de bambu sem preenchimento de concreto apresenta maior viabilidade estrutural e economica, podendo ser utilizada em obras de pequeno porte e de baixo custo.

Vigas de concreto reforçadas com bambu Dendrocalamus giganteus. II: modelagem e critérios de dimensionamento

This paper corresponds to the second part of a publication concerning the structural behaviour of concrete beams reinforced with bamboo. Modelling of concrete beams reinforced with bamboo-splint are presented and discussed. In addition, some design suggestions and hypotheses are presented. To perform the study, a Finite Element Program was used and some procedures were programmed and linked to it. The program was calibrated with the experimental data of eight concrete beams reinforced with bamboo-splint, whose results presented great accuracy. Finally, some design procedures were suggested and a practical example is given.

Structural behavior of concrete beams reinforced with pinned bamboo-splints

One drawback of bamboo as concrete reinforcement beams is the relative displacement between the two materials. The research reported in this paper aimed to experimentally investigate the improvement of bamboo-concrete-bond by means of nailing. Eight concrete beams were tested, six of them reinforced with Dendrocalamus giganteus Munro nailed bamboo-splints and two reference beams, reinforced with bamboo-splints without pins. Steel pins or bamboo pins were used. Two, three and four pins were nailed between bamboo nodes. Load-displacement and load-strain curves are presented and discussed. The results showed that the pins improved the beam stiffness; nevertheless, they reduced locally the transversal section of the bamboo splint and, consequently, the ultimate load. Finally, similar results were showed by beams reinforced by steel pins or bamboo pins.