Bamboo Mast for Lightweight Arquitecture

Bamboo is a pipe produced by solar energy. It is a plant of the graminae family which grows up all over tropical and part of subtropical regions of the world in more than 1250 species. High biomass production, high mechanical resistance, low specific weight and easy workability has done of bamboo a promise to future generations in relationship to sustainable construction systems. Bamboos of the Phyllostachys pubescens species are one of the most resistant and straight axis bamboos, used in China as material construction and other applications, as paper and fabrics. They are the most commercial bamboos of China and its forests covers 5,6 millions of hectare in that country. This exotic species is met on small plantations in Rio de Janeiro and São Paulo states of Brazil. Many characteristics turns bamboo a smart structural element: high resistance/weight ratio; natural nodes spaced along the culm which avoids local buckling and graded distribution of the fibers from inner to outer side of the thickness wall. So, the application of bamboos as tensile structures supports is a coherent choice since these modern tents characterize a lightweight architecture. Some structural bamboos can attain even more than 15 meters long with 10 cm mean diameter. To increase the load capacity of this slender bar and make feasible bamboo use as masts for tensile structures, an hybrid mast using bamboo as axis and 4 steel cables along of was designed and tested in the Structural System Laboratory LASE, and Structures Experimental Analysis Laboratory LAEES, respectively. In this paper it will be presented the results of the mechanical tests for 2 different masts with 6 meters long. Both masts have the same design but important differences which will be discussed in the paper.