[attachment=4943]
INFLUENCE OF SHAPE OF DIRECTRIX ON THE COST OF
RC CYLINDRICAL AND CONOIDAL SHELLS


1R.Gopi and 2Dr.N.Arunachalam
1PG student in Structural Engg, Bannari Amman Institute of Technology, Sathyamangalam, Tamil Nadu.
2Dean of Civil Engg, Bannari Amman Institute of Technology, Sathyamangalam, Tamil Nadu.

---

ABSTRACT
In order to study the most economical configuration of Cylindrical and Conoidal shells having different directrices to cover a given area, the following types of cylindrical and conoidal shell structures have been analyzed, designed and the costs of construction per sq.m have been estimated.
1. Circular Directrix
2. Parabolic Directrix
3. Inverted catenary Directrix
4. Cycloidal Directrix
The span of the shell is taken as 25m; chord width of the shell is 10m and the semi-central angle is varied as 30º, 35º and 40 º.
All the designs have been carried out by incorporating the recommendations of IS: 2210-1988 ‘Criteria for Design of Reinforced concrete shell structures and Folded plates’, IS: 2204-1962 ‘Code of Practice for Construction of Reinforced concrete shell roof’ and IS: 456-2000 ‘Code of Practice for Plain and Reinforced concrete’. The cost of roof to cover unit area has been estimated, compared and the most economical configuration has been identified.