Structural Engineering

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Browsing Structural Engineering by Subject "Adobe"

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    Mix Design for Increasing the Earthquake Resistant of Circular Adobe Buildings
    (Addis Ababa University, 2021-12) Habtamu, Hailemichael; Adil, Zekaria (PhD)
    Adobe buildings exist in different parts of the world and have been classified as unreinforced masonry structures. The construction technique of adobe is combining unfired clay mud and straw. The bricks are joined together with mortar made of mud and straw. This thesis studied the composition and mix ratio of soil to teff straw, which gave the maximum compressive strength by experiment. The result showed that the adobe prism specimen had a greater average confined compressive strength (987.66 KPa) compared with the same aspect ratio (1.66) in previous research. The prismatic specimens undergone consolidation at a higher strain range and further hardening of the prism makes the graph proportional (linear) before maximum stress is reached, after which the material was subjected to compression softening up to the ultimate strain sustained. Taking the maximum compression strength yielding mix ratio of 2:1 raw soil (58.9% of sand and 41.9% of silt and clay) to teff straw 'chid' (with lengths (cm) of 2-12, density (g/cm3) (using water) 1.20, diameter (μm) 230–270, tensile strength (MPa) 280–326, and modulus (GPa) 9.2–10.7) produced small-scaled adobe brick for a circular model adobe building and tested the earthquake resistance with a static tilt table test. The table was modified by incorporating a double-acting electric-driven hydraulic cylinder jack to avoid irregular vibrations that would contribute uncounted force to the model. The model resisted the horizontal lateral force 187% more than the previous research without a crack, though it could resist more if the base restraint was designed well. The specimen of this thesis was subjected to an increasing roof pressure load of 2 kN/m2 to 5kN/m2 continuously on the same model, that could equivalently express the performance of the circular adobe building model with the pseudo-static analysis, could resist seismic with a PGA of 0.71 and 0.63 respectively.