Threaded bolt, embedded in mortar
A hole is drilled into 2 or 3 Internodes, as well as through the same number of diaphragms
from the end of the tube. A steel bolt is inserted through the holes in the nodes and then
mortar is injected through the holes in the culm wall to fix the steel pole.
A second tube can be put perpendicularly on the steel bolt at the end of the tube: This
tube is drilled through completely in the middle of an internode and then gets connected
to the other culm. Again, this internode is filled up with mortar. A nut with a special
curved washer fixes the connection.
This washer has to fit exactly the curve of the culm, otherwise the high forces would
easily split the culm wall.
The tests at the
reached tensile forces of 70 kN. The initial slippage observed was very small. The
specimens failed because of splitting of the bamboo at the end of the tube. Load
capacity can be increased byadding a clamp.
Lateral steel tabs and bolts, embedded in mortar
2 to 3 internodes are drilled through completely at the end of a tube. Drilling has to be
carried out from outside everytime to not split the bamboo. Bolts with screw threads are
put through these holes and then the internodes are filled up with mortar. Now, a steel
sheet is connected with screws to the bolts. This steel sheet holds the second tube.
The steel sheet presses the second tube to the end of the first one like a belt. The
internode of the second tube, which is holded by the 'belt', must also be filled up
with mortar, to not get "squashed" in this area. Again, special formed washers are
used to fix the flat bar.
The connection type B showed a mean initial slip of approximately 1,5 mm, but resulted
in approximately 140 kN mean load, which is twice the load of connection type A. This
type failed because of extreme deformation of the holes of the steel sheet and splitting
of the bamboo tube.