Geotechnical and Geological Engineering

, Volume 30, Issue 6, pp 1323–1333

Factors Affecting Differential Settlements of Framed Structures

Authors

    • School of Civil EngineeringNational Technical University of Athens
  • Vasileios P. Papadopoulos
    • School of Civil EngineeringNational Technical University of Athens
Original paper

DOI: 10.1007/s10706-012-9546-x

Cite this article as:
Arapakou, A.E. & Papadopoulos, V.P. Geotech Geol Eng (2012) 30: 1323. doi:10.1007/s10706-012-9546-x

Abstract

The estimation of settlements, differential settlements and relative rotations on critical positions of the foundation is indispensable when carrying out analyses of both ultimate and serviceability limit states. The use of finite element method is recommended in cases where soil–structure interaction is expected to be significant. The scope of this paper is a contribution to the investigation of general trends in the effects of main parameters on the interaction. A typical five-span frame building with varying rigidity was examined by using finite element numerical method under 2-D conditions. Soil below the foundation was simulated as linearly elastic or elastoplastic medium. The effects of superstructure and foundation rigidity are closely related to the effect of soil deformability thereby analyses were performed in terms of relative rigidity factors. The effects of specific foundation types, namely isolated footings, flexible and rigid mat, were investigated in detail. The conclusions were focused on the development of normalized differential settlements, on the influence of the relative rigidity factor as well as on the determination of those cases where the interaction approach is necessary to be used for the analysis.

Keywords

Differential settlements Rotation Relative rigidity Footings Mat foundations

List of symbols

d

Equivalent thickness of the beam of the frame

df

Thickness of very flexible beam

dm

Thickness of medium stiffness of the beam

dr

Thickness of very rigid beam

E

Modulus of elasticity of the soil

Eb

Modulus of elasticity of the concrete

J

Moment of inertia

L

Length of the foundation

l

Span length

M

Flexural moments

Mo

Flexural moments when soil–structure interaction is ignored

Mr

Flexural moments of the extreme rigid foundation slab

maxs

Maximum settlement

MSF

Global safety factor

Rb = Eb × J/E × l3

Relative rigidity factor of the beam of the frame

Rf = Eb × J/E × L3

Relative rigidity factor of the foundation slab

t

Thickness of the foundation

tf

Thickness of very flexible foundation

tr

Thickness of very rigid foundation

V

Axial load of column

Vo

Axial load of column when soil–structure interaction is ignored

β

Relative rotation

Δ/L

Relative deflection

Δs

Differential settlement

Δs/l

Rotation

θ

Rotation

v

Poisson’s ratio

Copyright information

© Springer Science+Business Media B.V. 2012