Composite steel-concrete structures are widely used throughout the world for building and bridge applications because leading to economical and efficient structural solutions. Their design is carried out ensuring a number of limit states to be satisfied. This paper is concerned with the serviceability limit state of composite steel-concrete slabs, placing particular attention to the effects produced by concrete shrinkage on the structural response. In particular, a preliminary study is presented to outline the differences obtained in calculated deflections based on design models available in international guidelines or used by practicing engineers. Only simplysupported static configurations have been considered in this paper. In the initial part of the paper, the main aspects related to the time-dependent behaviour of concrete are introduced, followed by the description of three service design models which range in the approach used to account for shrinkage (i.e. varying from omitting shrinkage in the deflection calculations to adopting different representations for its variation over the slab thickness). The differences observed in these preliminary comparisons highlight the significance of including a non-uniform shrinkage gradient in serviceability deflection calculations. In particular, the non-uniform shrinkage profile develops due to the inability of moisture to dry from the underside of the slab due to the presence of the steel sheeting and has been observed in recent experimental long-term experiments. These shrinkage requirements are currently being included in the revised Australian composite guidelines expected to be available for public comments in 2016.

Comparison between design models for serviceability limit states of composite steel-concrete slabs

LEONI, Graziano;
2015-01-01

Abstract

Composite steel-concrete structures are widely used throughout the world for building and bridge applications because leading to economical and efficient structural solutions. Their design is carried out ensuring a number of limit states to be satisfied. This paper is concerned with the serviceability limit state of composite steel-concrete slabs, placing particular attention to the effects produced by concrete shrinkage on the structural response. In particular, a preliminary study is presented to outline the differences obtained in calculated deflections based on design models available in international guidelines or used by practicing engineers. Only simplysupported static configurations have been considered in this paper. In the initial part of the paper, the main aspects related to the time-dependent behaviour of concrete are introduced, followed by the description of three service design models which range in the approach used to account for shrinkage (i.e. varying from omitting shrinkage in the deflection calculations to adopting different representations for its variation over the slab thickness). The differences observed in these preliminary comparisons highlight the significance of including a non-uniform shrinkage gradient in serviceability deflection calculations. In particular, the non-uniform shrinkage profile develops due to the inability of moisture to dry from the underside of the slab due to the presence of the steel sheeting and has been observed in recent experimental long-term experiments. These shrinkage requirements are currently being included in the revised Australian composite guidelines expected to be available for public comments in 2016.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11581/391857
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