Catalan Shell: Research through Experimentation

from Catalan Shells: Researching and experimentation Semester 9 Studio; with @jaypatel1711

MASONRY SHELLS

Researching and Understanding through Experimentation

Indubhai Parekh School of Architecture

This paper presents the study on Catalan Vault construction technique and its executionmethods and learnings. It shows how this construction technique is more economical as well asstructurally efficient than conventional techniques .

This paper is primarily addressed to educators as well as pupils of architecture. Anunderstanding of this technique, as one of the means to construct shell will help them provide forbetter solution to address their design problems in an innovative manner.

Grateful acknowledgment is here made to those who helped this group during the site work, namely batch mates, juniors of batch 17 and last but not least to various faculties for their invaluable advice . Batch mate Bhumit Savsaviya’s contribution is especially acknowledged. We are indebted to Mr. Raj Hadvani of Gopal Industries for his support in this research. This work would not have reached its present form without their invaluable help.

Sampling

Intention Sampling is done using several materials to test and understand the behavior of brick and thebinding agent and their relationship. It enabled us to understand the behavior of the system, formand its execution. Material used and its form are the principal governing factors that determines thefailure or the success of the system.

Sampling 1

The first sampling was done to understand the working of the binding agent, Plaster of Paris with the Terracotta block. It was the first rudimentary attempt to understand the basic execution methods. The wooden formwork was used just as a guide to achieve the correct form. The sample failed when

additional load was applied, due to the shifting of the springing point. Due to failure, the study of thebehavior of the system under load was left incomplete.

Sampling 2

The second sampling was done to experiment and execute the vault without a guide, using terracotta hollow blocks and POP. The aim was to examine the binding strength of POP. The vault was made up of two bays of arches. The form achieved without using any guide did not follow the desired curvature. In spite of this, the vault withstood self-weight. This attempt still classified as “Gravity System” and not “Timbrel System”.

Sampling 3

The third sampling was done with thin Kota stone tiles with POP as binding agent. The Kota stone tiles, since not as permeable as terracotta, was not able to bind properly as per earlier arrangement. Hence an alternating course arrangement (Fig. 14) was carried out. This changed the form of shell. The principle reason of failure was due to the its inability to withstand the vibration and movement caused by hand during the execution. Since this was a free standing shell, we felt that had both the end of the shell been supported, failure would have been avoided. We also felt the need of a guide, which would have assisted in achieving correct catenary curve that might have avoided the failure as well.

Sampling 4

Learning from the previous sampling attempts, the 3 course deep foundation was carried out at the four springing points of the cross vault. The distance between the piers is 2.21m and the internal diagonal distance is and the internal diagonal distance is 3.22m (Fig. 16). The piers, extending from the foundation level, terminated two courses above ground level. To deal with side thrust, buttresses were introduced at the side of pier for providing further stability.