Relationship Between Temperature and Earth Pressure for a Rigidly Framed Earth Retaining Structure
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ORIGINAL PAPER
Relationship Between Temperature and Earth Pressure for a Rigidly Framed Earth Retaining Structure Magued Iskander
Received: 23 January 2012 / Accepted: 11 December 2012 / Published online: 5 January 2013 Springer Science+Business Media Dordrecht 2012
Abstract The relationship between temperature and earth pressure acting on a rigidly framed earthretaining structure (RFERS) subject to wide temperature variation was explored. A distressed RFERS open concrete garage that retains 11 m (36 ft) of soil was instrumented. After some repairs, movement of the building was monitored and recorded hourly for a period of four and a half years. The monitoring revealed complex temperature-dependent soil–structure interactions. The measured displacements were used to calculate the earth pressure coefficient using closed form equations that were developed by treating the structure as an equivalent cantilever beam, and calibrating the expression using a total of 42,000 FEM models. The data indicated that the coefficient of earth pressure behind the monitored RFERS had a strong linear correlation with temperature. During the cold season the building contracted, and the retained soil followed. During the hot season, the building was unable to overcome the earth pressure, thus it expanded away from the soil, resulting in a cumulative annual displacement. The coefficient of lateral earth pressure changed by approximately 0.005/C, varying in the range of 1.25–1.5, depending on the season. The study also reveals that thermal cycles, rather than
M. Iskander (&) Polytechnic Institute of NYU, Six Metrotech Center, Brooklyn, NY 11201, USA e-mail: [email protected]
lateral earth pressure, caused some of the structural elements to fail. Keywords Failure Distress Forensic Temperature Thermal effects Earth pressure Coefficient of thermal expansion Soil–structure interaction Segmental bridges Jointless bridges Concrete
1 Introduction Structures placed on hillsides often present a number of challenges and a limited amount of economical choices for site design. An option often employed in design is to use the building frame as a retaining element, comprising a rigidly framed earth retaining structure (RFERS). A RFERS is a structure that retains earth on one side and resists lateral earth pressure by rigid frame action, without the presence of any other retaining elements or forces against lateral displacement (Fig. 1). An instrumentation program was undertaken to monitor the movements of a four-story reinforced concrete RFERS, exhibiting signs of large deformation and severe structural distress including the failure of a column (Iskander et al. 2001). The structure was repaired, and then monitored for 4.5 years. Earth pressure behind a RFERS typically begins as a
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Geotech Geol Eng (2013) 31:519–539
AREA TO BE BACKFILLED
EARTH PRESSURE
AREA TO BE EXCAVATED
AREA TO BE BACKFILLED
Fig. 1 Typical rigidly framed earth retaining structure (RFERS)
hydrostatic distribution following the conventional
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