Large settlement of oil storage tanks is a problem that may face many companies that are engaged in the storage, processing and production of fuel. If the actual settlement exceeds allowable settlements specified by applicable codes and standards, a company is required to repair or even further demolish a tank and invest in rebuilding a new one with all the hazards that accompany demolishing a tank that is being used to store flammable products.

This is also a problem because of the safety and environmental impact of underestimating a settlement case that might lead to product leaks, fires, and fatalities.

The API STANDARD 653 "Tank Inspection, Repair, Alteration and Reconstruction" provides limits to determine maximum acceptable settlement for tank shell. Since these limits were mostly developed by linear shell theories, the resulting limits are in fact very conservative. Field observations have shown that tanks are in good operating condition even though the limits are well exceeded. The main objective of the current study is to find practical limits of settlement based on more elaborate non-linear analysis that can be applied to tanks operated in Egypt. This research questions the maximum acceptable limits of settlement, set by applicable standards, to determine which of these limits are conservative and to what extent.

A non linear finite element analysis was conducted using the MSC MARC program. Pro-Engineer and MSC PATRAN were used to model the tanks and MSC MARC solver was used for the finite element analysis. Several settlement modes were studied among which are the following:

- Shell planar tilt

- Shell out of plane settlement

- Bottom localized settlement near the shell, and

- Bottom localized settlement remote from the shell

The tanks were studied under own weight and hydrostatic pressure. Simulated data for settlement were used to impose planar and out of plane settlements.

The finite element analysis demonstrated that the limits for tank shell settlement, and for tank bottom settlement, are very conservative. Suggested practical limits are proposed.


Construction Engineering Department

Degree Name

MS in Construction Engineering

Date of Award


Online Submission Date


First Advisor

Medhat Haroun

Committee Member 1

Ashraf Osman

Committee Member 2

Mostafa Mossaad

Committee Member 3

Safwan Khedr

Document Type



134 leaves :

Library of Congress Subject Heading 1



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Call Number

Thesis 2006/94