Abstract Concrete foundation slabs are usually exposed to unilateral drying during the curing process. The unilateral drying causes an axial shrinkage and a concave curvature of the construction. The curvature results from the fact that the upper part of the slab is drying and shrinking faster than the lower part. This is called gradient shrinkage. A problem occurs when the slab is considered fully restrained by adjoining structural parts. The deformations caused by axial contraction due to the constant part of the shrinkage and the curvature caused by gradient shrinkage of the slab are then prevented by the fact that the slab is fully restrained. When the shrinkage and the curvature are prevented, constraints occur in terms of an axial force and a bending moment. These constraints cause cracking in the upper part of the slab. These cracks can cause inconveniences for the user of the slab and the cracks should therefore be minimized. It is important to determine the precise magnitude of the constraints so that sufficient amount of reinforcement can be applied into the concrete and the crack widths can be reduced. The construction consultancy company WSP has an interest in structural design methods for reducing the risk for concrete cracking through establishing engineering guidelines for the structural design of foundation slabs which are exposed to axial and gradient shrinkage. The result in this report shows the magnitude of the constraints for slabs of varying thickness and molded with different types of concrete. The constraints are later used to determine the crack widths. Two different reinforcement standards, both in compliance with the minimum requirements of Eurocode 2, are included in the study. A conclusion based on the results shows that the amount of reinforcement can be reduced in foundation slabs up to 300 millimeters thickness without significant impact on the crack widths.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-184587 |
| Date | January 2012 |
| Creators | Edlinger, Robert, Svansbo, Karl |
| Publisher | Uppsala universitet, Byggteknik, Uppsala universitet, Byggteknik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
Page generated in 0.0015 seconds