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Construction with Bamboo
Diplom-Ingenieur Christoph Tönges

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Due to the hollow body structure of bamboo, the connection possibilities of conventional lumber can be only partially applied. By injecting concrete into the internodes and adding steel reinforcement it is possible to produce very stiff connections.
	(58) Roof of a kiosk, bottom view

		Bolts If the expected forces are not too high, it is sufficient to screw the Guadua elements together. The concrete injection therefore is unnecessary. Threaded bolts and screw nuts proved themselves since they can be cut easily to the needed lengths.
	(59) Connection of support/truss with bolts

Bolting with steel tabs/plates To transfer tensile forces, steel laschen on the sides of the culm are mounted with bolts through the internodes which are filled up with concrete afterwards. So the enormous tensile strength of bamboo can be used. This connection technique was frequently used by Simón Vélez and was studied extensively by the FMPA-Stuttgart for the construction of the ZERI Pavilion at the EXPO 2000 in Hannover / Germany. More about the construction of this joint!
	(60) Bolts with steel tabs/plates

		'Fish mouth' If a Guadua culm meets perpendicular another, a fish mouth guarantees an actuated/frictional connection. For the manufacture both chisels as well as special drills are suitable. With the special drill, the 'fish mouth' can be produced fast and clean, although this is the more expensive way.
	(61) 'Fish mouth'

Cross bar A cross bar, that is bolted to the columns, is usually used to connect an knee brace with the column. If the cross bar is not collocated between two column members, it has to be supported (cam connection) in order to prevent twisting. At high forces a concrete filling in the cross bar prevents crushing.
	(62) Negative example	(63) Positive example

		Cam connection The struts connected, to the support transfer the forces through an added block shear connector which is bolted to the support. In the image at the left the cam itself turns into a vertical member of the main support - the addition of the strengths therefore can be read in the supporting structure.
	(64) Support with cams

Offset The cam possibly can be replaced by a offset, which provides a frictional connection, too. The 'pre-timber' should contain at least two knots. A bolt provides security through reducing the shear forces in the 'pre-timber'.
	(65) Connection with offset

		Clamped support with four or more members At least four posts of a support can be clamped to a foundation with cemented connection irons of. The result is a flexurally rigid connection.
(66) Clamped support	(67) Position of the reinforcement

Clamped support with one culm To attain a rigid connection with one single culm, a steel tube is cemented centrically. The concrete is injected through a hole in the Guadua culm above the steel tube.
	(68) Single restraint	(69) Steel tube

		Simply supported connection Using a plastic bottle to form the column base raises the Guadua out of the splash water zone. A disadvantage may be the very low concrete cover and thus the danger of corrosion of the steel bar.
(70) Simply supported connection	(71) Filling in the concrete

Using a plastic bottle to form the column base raises the Guadua out of the splash water zone. A disadvantage may be the very low concrete cover and thus the danger of corrosion of the steel bar.
	(72) 'Bottle formwork'