Livaoglu, Ramazan; Cakir, Tufan; Dogangun, Adem; Aytekin, Mustafa

The reliability and/or stability of the lifeline structures against failure under seismic loads are of critical concern, and must be studied carefully. Therefore, the main objective of this paper is to demonstrate the commonly encountered backfill effects on the dynamic response of rectangular tanks. However, only the exterior wall of the tank which interacts with both the backfill and fluid is tackled, as each part of the structure shows considerable differences in terms of both the load bearing mechanisms and the geometrical and positional differences. Finite element analyses are employed, taking into consideration the fluid-wall-backfill interaction. The analyses are conducted to observe whether or not both backfill and wall behavior can be affected by variation of the internal friction angle. For that purpose, some comparisons are made on vertical displacements of the backfill, roof displacements, stress responses, etc., by means of internal friction angle variations of the backfill from 25 degrees to 40 degrees. Consequently, it is observed that the variations on maximum vertical displacements are affected considerably. In contrast, the maximum stress responses are affected partially. However, the inertial effects of the backfill show that pseudo-static approximations may be insufficient to understand the dynamic behavior of the backfill-wall-fluid system. (C) 2011 Elsevier Ltd. All rights reserved.

Ikizler, S. Banu; Aytekin, Mustafa; Nas, Evin

The reduction of transmitted lateral swelling pressures on retaining structures constructed in expansive soils is investigated. Swelling pressures will develop if the soil is not allowed to swell freely. The magnitude of swelling pressure depends on the degree of expansion permitted. When a little soil expansion is allowed, the swelling pressure may be decreased considerably relative to the case of no expansion. This study examines the role of expanded polystyrene (EPS) geofoam in accommodating soil expansion and hence reducing swelling pressures on adjacent structures. Several hypothetical cases are presented whereby reductions on the transmitted lateral pressures due to expansive soils are examined for different thickness of EPS geofoam.