SHRINKAGE AND THERMAL EFFECTS IN R/C FLAT PLATE AND RAFT FOUNDATION

M. Elgarayhi, Reda; E. El-Metwally, Salah; E. El-Zoughiby, Mohamed

doi:10.21608/erj.2019.122534

SHRINKAGE AND THERMAL EFFECTS IN R/C FLAT PLATE AND RAFT FOUNDATION

Document Type : Original Article

Authors

¹ Graduate Student Structural Engineering Department, Mansoura University, El-Mansoura, Egypt

² Prof. of Structural Concrete

³ Associate Prof. of Structural Concrete,

10.21608/erj.2019.122534

Abstract

In this study, the effect of shrinkage and temperature variation on the
behavior of long span reinforced concrete flat plate system and raft foundation supported
directly on soil or piles, has been examined via the nonlinear finite element analysis. In
the analysis, shrinkage has been considered as a drop of temperature of 30

oC for the flat
plate system and of 20

oC for the raft foundation. A change of temperature of uniform
profile and of nonlinear gradient have been considered. The analysis accounted for
material nonlinearity and it has been performed for all possible load combinations.
The results of analysis revealed that material nonlinearity plays a major role in the
response of the structure for temperature and shrinkage effects since its presence
remarkably reduced the adverse effect of the two factors. Shrinkage and temperature
variation had more significant effect on slabs than on rafts. Their effect on concrete
stresses was not critical in slabs and had no significance in rafts. On the other hand, such
effect on steel reinforcement was noticeable in rafts and significant in slabs. This led to
the conclusion that the effect of both temperature variation and shrinkage can be
accommodated by additional reinforcement. In slabs, for an accurate assessment of
deflection, it is important to account for both factors in the analysis.

Keywords