An empirical model of ribbed cylindrical glass reinforced plastic tanks

Ribbed cylindrical Glass Reinforced Plastic (GRP) tanks are currently designed using simplified theory the results of which are then verified by extensive destructive testing. This approach is expensive and can only generate non-optimal design solutions. In addition, there is often a high degree of discrepancy between theoretical and experimental results which necessitates the use of undesirably high factors of safety, which in turn results in the excessive use of material with the concomitant increase in cost, weight and manufacturing time. The primary aim of this investigative research was to develop a more deterministic and accurate design method of predicting the structural integrity and performance of underground cylindrical GRP tanks using non-destructive testing. Linear and non-linear Finite Element Analysis (FEA) techniques, validated against experimental results, were used to analyze a large number of underground ribbed cylindrical GRP tanks. The outcome of which was then expressed in the form of an empirical 'Design Formula' which provides a comprehensive solution to ribbed cylindrical GRP tank design for a wide range of tank sizes, laminate lay-ups and material properties. It is intended that the application of this method will eliminate the need for the expensive field tests that are currently required by design codes and standards.