Next: Current Methods for Seismic Up: DEVELOPMENT OF PRACTICAL DESIGN Previous: Introduction

Damage to Unanchored Liquid Storage Tanks in Previous Earthquakes

Many researchers addressed the observed Damages to unanchored liquid storage tanks during previous sever ground motions. Rinne [10] reported that the Prince William Sound, Alaska, earthquake of 1964 caused more extensive damage to oil storage tanks, most of which were unanchored, than to other structures. Shell buckling near the bottom of unanchored tanks was a phenomenon experienced during this earthquake. In few tanks, buckling was followed by a total collapse of the tank. For most tanks, uplift occurred typically around the periphery of the tank bottom plate, which was lifted as much as two inches off the supporting foundation, causing yielding and plastic deformations in the tank bottom plate. Hanson [4] discussed the behavior of liquid storage tanks during the same earthquake and reported that earthquake forces can cause an uplift of the tank edge, and this uplift increases the possibility of the tank damage and subsequent loss of its contents.

A brief description of the structural and nonstructural damages of unanchored tanks during the 1979 Imperial Valley earthquake was presented by Haroun [5]. He reported that buckling of the bottom of tank shells due to excessive compressive stresses, damage to fixed roofs due to liquid sloshing and failure of attached pipes due to their inability to allow for the shell movement, had occurred.

The 1983 Coalinga earthquake subjected many unanchored oil storage cylindrical tanks to an intense ground shaking. Damages occurred to these tanks were studied by Manos and Clough [8]. Observed damages included elephant foot buckling of the tank wall at the base, joint rupture, top shell buckling, bottom plate rupture, damage to floating roofs and pipe connections, and spilling of oil over the top of many tanks.

Next: Current Methods for Seismic Up: DEVELOPMENT OF PRACTICAL DESIGN Previous: Introduction