CHARACTER ANALYSIS OF APPROXIMATED REAL PLANT
STRUCTURE AND ITS APPLICATIONS TO BUILDING
CONSTRUCTION
Peter KRUŠINSKÝ*, Ján KORTIŠ**
1. Introduction
Nature is a rich source of ideas and inspires a lot of famous scientists. Civil Engineering is
inspired by the nature too and the bionic as a research area helps us to design new attractive
buildings. This is the reason why we analysed a leaves of burdock and looked for a new
option of design modern structures. In this papers is described the analysis of a stem which
gave us design fundamentals for numerical models.
2. Analysis of the burdock leaves
We chose a leaves of Arctium lappa (greater burdock). This plant has a large heartshaped leaf. At first we made geometric model which approximated vein skeleton (Fig. 1).
This can be used like a skeleton for some types of building. The cross-section of veins are
changed and vein are thinner at an end of the leaf. The veins were designed as a pipe. We
looked for a relation between diameters of cross-sections of thinner pipes at an end of the leaf
and thicker pipes at a beginning of the leaf. This relation we compare with relation between
diameters which were measured on the real leaves. This analysis didn´t solve any problems of
stability. We supposed only vertical load and the model didn´t include a stem. The forces
representing the load were placed on the joins of the approximated vein skeleton. The values
of loads represented the uniform vertical pressure.
*)
Peter Krušinský, Ing. PhD., University of Žilina, Department of building enginnering and urban planning,
Univerzitná 8215/1 010 26 Žilina, Slovakia. E-mail: [email protected].
**)
Ján Kortiš, Ing., University of Žilina, Departemnt of structural mechanic, Univerzitná 8215/1 010 26 Žilina,
Slovakia E-mail: [email protected].
Fig. 1 Burdock and his geometric approximation.
In the real structure the stem is an important part. Its main function is support for leaf.
So we analysed internal structure of stem. We used optical microscope to see internal
structure of stem. The result of this you can see on the (Fig. 2). The cross-section is circle
with many circle-shape holes. We assume that the main part of the stem is made from thin
pipes. We created a column based on this assumption. But we made a symmetrical circle
cross-section made from six circles placed around one circle. The external cover of the stem is
replaced by one circle. All circles represented a thin steel pipes. The thickness of pipes is 5
mm. We used this cross-section for 2,5 m high column.
Fig. 2. The internal structure of stem (cross section)
3. Computer model based on a stem of a leaf
We used beam elements and shell elements and we made two types of model. For
computer model was used steel like a material which is suitable for thin structure. First
simpler beam model was used to find critical loads which case that the ideal column to be
unstable. We used three types of cross-sections (Fig.3). All cross-sections have the same
width. Two of them are typical cross-sections which are usually used. The third cross-section
is based on internal structure of the stem. Then we divided the critical loads by the weight of
the column.
Fig. 3. Cross-section used in analysis a/ circle 300/20, b/ HEB300,
c/ Cross-section based on stem
The shell elements were used for the second models. We made three types of the models.
Two of them represent current types of steel columns. The last column is based on internal
structure of the stem. The buckling problems are specific for column so an initial imperfection
was ordered. The initial imperfection was based on the first eigenvectors and we ordered
value of initial deformation on the upper nodes of the column. The initial displacement on the
upper nodes was 0,1 m for all types of columns. We applied vertical force 10 kN on the upper
part of column. The results of analysis were a band plot of effective stress. We divided the
maximal values of the effective stress by weight of columns. The last step of analysis was
comparison of the results. For this reason was made a table. You can see it on the next page
(Tab. 1).
Fig. 4. Band plot of effective stress a/ circle 300/20, b/ HEB300,
c/ Cross-section based on stem
We found that the column based on the stem cross-section is compared with other common
types of columns. The circle cross-section has the best results. But the thickness of shell is
four times bigger than thickness of shells which are used for column based on stem.
Comparison of results
Table 1
Type of cross-section
Kritical force
F[ kN]
Weight
m [kg]
F/m
Max effective
stress [Mpa]
σ/m
HEB300
Circle cross-section 300/20
Stem cross-section 300/5
3061,44
7253,9
4723,62
409,65
483,27
418,54
7,473306
15,01004
11,28595
1,71
0,96
1,4
4,17
1,99
3,34
4. Conclusions
The plant structures have specific function. For most of them is the main function
photosynthesis to convert resources from the atmosphere by using the sunlight. The plants
used the leaves as the factories for this purpose. And they have strong skeleton to resist same
bad weather conditions. So we can analysis it and look for a new option of design. We
analysed column based on the stem of the burdock. The main advantage is thinner plates of
the material to achieve the same carrying capacity. This can be applicable for some new types
of the thin layers materials.
ANALÝZA APROXIMOVANEJ RASTLINNEJ ŠTRUKTÚRY
A MOŽNOSTI JEJ VYUŽITIA NA STAVEBNÝCH KONŠTRUCKIÁCH
Peter KRUŠINSKÝ, Ján KORTIŠ
Bionika sprevádza človeka od začiatku jeho vývoja a umožnila mu na základe pozorovaní
prírody získať mnohé poznatky. Príroda je teda bohatým zdrojom informácií a inšpirácie.
Preto aj v stavebníctve a architecture môžeme využiť tento bohatý zdroj informácií a pokúsiť
sa na základe rastlinných štruktúr navrhovať nové zaujímavé a atypické stavby.