Bamboo and Steel are structural materials with different engineering qualities used for the construction of buildings and other engineering construction related purposes.
The rapid growth and maturity rate of bamboo, sustainability, aesthetics, and acceptability; its strength properties, low cost, makes it worth investigating as a substitute structural material for steel. However, bamboo is relegated and underrated to steel as a structural material in construction generally, as such; it has been mainly employed for none/or marginal engineering purposes. The current study assessed bamboo for its tensile strength and ability to carry load in comparison to steel to highlight its acceptability or otherwise of bamboo as a substitute for steel as structural member in engineering construction.
Bamboo is known to have over 1200 different species worldwide which makes it a common and easily accessible material; it is also known to have been widely used in building construction in different parts of the world. Some species of bamboo can grow as tall as 35inches (875mm) within a 24-hour period.
Bamboo has a high compressive strength than wood, brick and concrete and exhibits a tensile strength that rivals steel. Bamboo has several properties of engineering material like steel used in construction but unlike wood, bamboo is known to have more evenly distributed yield stress strength; this is due to the absence of ray and knots in its stem.
Today, bamboo is employed in building construction not only because of strength but other properties which makes it favorable for construction works such as; resistant to pest, sturdiness, flexibility and availability.
Bamboo has been used in constructing; walls, support structures, piers, roof, floor and room dividers amongst other things. These engineering structures are constructed with bamboo not for aesthetics alone but the amazing engineering qualities of the material. Steel on the other hand has dominated in engineering construction because of its load bearing strength, yield stress strength etc.
Bamboo has strong mechanics and good adaptability, it is easy to be processed which causes it to be used for wide range of architectural and industrial purposes. The comparative tensile strength of bamboo is about that of wood but has a compressive strength 10% higher than wood. Although, the tensile strength of steel is 2.5-3.0 times higher than bamboo and the specific gravity of steel is 6-8 times than that of bamboo;
But by counting their tensile strength/unit weight (bamboo vs steel), the tensile strength of bamboo is 3-4 times than that of steel. It is based on this fact that the study sets out to compare the tensile strength of bamboo to steel as structural engineering material.
TEST RESULTS SHOWING THE COMPARATIVE TENSILE STRENGTH PROPERTIES OF STEEL AND BAMBOO
[1] HIGH YIELD STEEL BAR
TENSILE STRENGTH (N/mm2)
10mm – 457.13
12mm –Â 689.12
16mm –Â 711.61
20mm – 713.40
25mm –Â 792.90
BREAKING ELONGATION (%)
10mm –Â 19.25
12mm –Â 26.10
16mm –Â 35.27
20mm – 30.72
25mm –Â 26.11
[2] MILD STEEL BAR
TENSILE STRENGTH (N/mm2)
10mm – 290.49
12mm –Â 508.08
16mm –Â 508.71
20mm – 372.98
25mm –Â 701.74
BREAKING ELONGATION (%)
10mm –Â 51.61
12mm –Â 39.57
16mm –Â 55.53
20mm – 23.68
25mm –Â 29.65
[3] BAMBOO
TENSILE STRENGTH (N/mm2)
10mm – 31.55
12mm –Â 31.07
16mm –Â 68.82
20mm – 62.66
25mm –Â 94.60
BREAKING ELONGATION (%)
10mm –Â 0.00
12mm –Â 0.00
16mm –Â 15.07
20mm – 12.10
25mm –Â 10.91
From the Test
[1] High yield steel bar has the highest resistance to tension giving a tensile strength ranging from 457N/mm² -792N/mm². Mild steel on the other hand, has tensile strength values from 290N/mm²-508N/mm². Bamboo can be said to be very poor in tension giving a tensile strength of 31N/mm²- 94N/mm².
[2] The ductility of steel allows it to undergo plastic deformation and necking before breaking. Bamboo undergoes brittle failure. i.e., it breaks sharply without plastic deformation. This property is demonstrated from the result of breaking elongations obtained. Mild steel is most ductile giving a breaking elongation ranging from 30% – 52%; followed by high yield steel with a value of 19% – 26%. Finally Bamboo which undergoes brittle failure gives a breaking elongation of 0% – 15%.
[3] The result indicates that bamboo unlike steel has a very poor tensile property and undergoes brittle failure when loaded. This is a huge disadvantage of using bamboo as a structural member in building construction. Therefore, the study concludes that due to the minimal breaking force (FB) of bamboo, it cannot be employed as a main structural member in buildings and other heavy engineering works but can be used for partition walls, ceilings, roofs and other areas of lightweight engineering construction that is not heavy load bearing.
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