Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

The paper presents a case history of a 5-storey RC building in Athens (Greece), seriously damaged due to differential settlement. Built in 1968, the damaged structure is founded on spread footings, lying on very soft clayey soil. For more than 30 years, no damage had been observed. In 1999, construction of an adjacent 5-storey RC building begun, and shear cracks started appearing. Inclined at 45o, the cracks implied damage due to differential settlement. The owners of the damaged building filed a law suit, claiming that the damage was due to additional loading by the under-construction adjacent building. Measurements conducted in 2011, revealed that the differential settlements were of the order of 5 cm. However, the present study also revealed that the damaged building had a number of construction defects, with the most important one being the absence of tie beams. In order to assess the relative importance of the two factors (construction of the adjacent structure vs. construction defects), numerical analyses were conducted modeling both buildings in detail, and taking account of the construction sequence. It is shown that due to the defective foundation of the damaged building, almost 70% (3.5 cm) of the differential settlement had already taken place before construction of the adjacent building. The latter, founded on a slab foundation, settled by about 3 cm, increasing the differential settlement of the damaged building by roughly 1.5 cm. No damage would have taken place, had the building been constructed according to code specifications.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Structural Damage of a 5-Storey Building: Differential Settlement Due to Construction of an Adjacent Building or Because of Construction Defects?

Chicago, Illinois

The paper presents a case history of a 5-storey RC building in Athens (Greece), seriously damaged due to differential settlement. Built in 1968, the damaged structure is founded on spread footings, lying on very soft clayey soil. For more than 30 years, no damage had been observed. In 1999, construction of an adjacent 5-storey RC building begun, and shear cracks started appearing. Inclined at 45o, the cracks implied damage due to differential settlement. The owners of the damaged building filed a law suit, claiming that the damage was due to additional loading by the under-construction adjacent building. Measurements conducted in 2011, revealed that the differential settlements were of the order of 5 cm. However, the present study also revealed that the damaged building had a number of construction defects, with the most important one being the absence of tie beams. In order to assess the relative importance of the two factors (construction of the adjacent structure vs. construction defects), numerical analyses were conducted modeling both buildings in detail, and taking account of the construction sequence. It is shown that due to the defective foundation of the damaged building, almost 70% (3.5 cm) of the differential settlement had already taken place before construction of the adjacent building. The latter, founded on a slab foundation, settled by about 3 cm, increasing the differential settlement of the damaged building by roughly 1.5 cm. No damage would have taken place, had the building been constructed according to code specifications.