Construction with Bamboo – Bamboo Cities!

Have you heard about including bamboo in construction as a structural material?

Of course you have!

But you might have known about it at an experimental level right? here’s a great news update then,

Bamboo is being used for construction in very large scale

 

Yes, being good in Mechanical properties and several others Bamboo proves to be strong contender in concrete-replacement race. Bamboo has two to three times properties than other construction materials like timber, steel, etc.

 

To start with, there’s a wide range of species of Bamboo. They have same quantities with varying values. Here’s a review of Mechanical properties of bamboo..

The strength tests of bamboo already have been conducted by universities around the globe. And Bamboo have proved its superiority by having superior strength than conventional materials. But, this is not enough in this fast changing world. Additional properties due to which Bamboo-as a structural material, stands out are, Durability, Fire Safety, Environment Impact, User Safety and Energy Efficiency. For these Mechanical properties an International ISO 22157 standard has been published which is a remarkable step.

 

But being used in construction as a structural member and having assured about the strength parameters of Bamboo, a discussion on compressive strength, tensile strength and shear strength is much needed in this article.

Compressive strength of Bamboo

This test is required in two ways, one along the grain and the other is perpendicular to the grain. But ISO 22157 recommends test along the grain, so we will discuss about it only.

Bamboo stem is broadly classified in three parts top, middle and bottom. As bamboo does not have uniform c/s through out its length, this classification is necessary. The strength is directly proportional to the diameter of bamboo.

While testing, care is taken that node is avoided from the sample. Nodes are the strongest part of bamboo stem and the stem without node is weakest. Which means the possibility of false results is already reduced.

The compressive strength of bamboo is approximately between 40 and 80 N/mm2 (which is 2 to 4 times as that of timber species). The main factors that influence the compressive strength of bamboo are diameter, age and moisture content. Bamboo with low moisture content has a higher compressive strength than bamboo with high moisture content.

 

Tensile Strength

The maximum tensile strength of bamboo is determined by testing the fibers (bamboo strips) and not on entire culm samples. The ISO 22157 standard provides guidelines for tensile strength parallel to grain but not for tensile strength perpendicular to grain.

Test procedure : 3 strips directly from the lower part, the middle part and the upper part of the entire bamboo stem. Each strip is between 10-20 mm wide, having thickness of the bamboo culm, and is 100 mm long. Moisture content of each sample must be determined and samples must have a node. As the fiber direction of the node is opposite to the fiber direction of the internode, the node is here considered the weakest point of the stem.

The average tensile strength of bamboo is lies roughly around 160 N/mm2 which is often 3 times higher than most conventional construction grade timbers.

 

Shear Strength

This is important because, shear strength will guide us in designing the whole joining system and connections. Similar to above tests three samples should be taken from three parts of stem, top, middle, bottom respectively. Half of the sample should contain node and half should not. Thicknesses at various distances where shear will be acting should be measured.

Shear stress parallel to grain is approximately 10 times lower than compressive strength and even 20 times lower than the tensile strength of the same bamboo species. Still, the shear strength of bamboo is often twice the value of popular timber species.

To know more about tests on Bamboo click here

These were tests and Mechanical properties of Bamboo as a structural member, but wait here are some structures of bamboo. After looking at these pictures you will say, “F#ck tests and strengths, I am building my house with Bamboo only!”

 

 

HWCD’s Floating Bamboo Courtyard Teahouse is a Zen Space For A Tea Party

sharma-springs-ibuku

A Penthouse!

ibuku-bamboo-bridge

A Bridge!

playa-viva-treehouse-1020x610

A cylindrical House on the beach!

So folks, to know more about this new fashion click here (Source)

And for many more #UpdatesToTheIndustry  follow @Sthapatyablog

 

 

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