A Theoretical Study on Differential Settlements of Reinforced Concrete Frame Structures Considering their Nonlinear and Time-dependent Behavior
Construction. Civil engineering
This paper describes an analytical method of assessing the interactive behavior of a soil-structure system. Structures under considerations are reinforced concrete frames, which are analyzed theoretically including their nonlinear and time-dependent behavior, and the creep effect of concrete can be evaluated quantitatively. A numerical example is given of the use of the method applied to a reinforced concrete space frame structure.
The main conclusions obtained are summarized as follows:
1) The additional stress (a kind of stress caused by differential settlements) is reduced due to the relaxation caused by creep of concrete, compared with the results obtained from the elastic or the elasto-plastic theory. And the effect of relaxation is more remarkable for the internal force per unit area of concrete or reinforcements than that for cross-sectional forces (bending moments, axial forces, etc.).
2) The effect of rigidity of structures, which suppresses the differential settlement, is reduced by the creep of concrete and the additional stresses are also reduced, and so this effect works to advantage on design.
3) Whan the structure settles differentially, the reaction of foundation changes remarkably from the initial reaction. It will be possible in designing foundations that some troubles may occur by taking merely the initial reactions into account.
4) Though the proposed method evaluates the stress superposition properiy, the conventional analysis based on Winkler's spring model overestimates the rigidity effect of structures because this method does not consider the effect of stress superposition in the foundation soil.
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Departmental Bulletin Paper
Departmental Bulletin Papers
Graduate School of Engineering