| dc.description.abstract | Hollow core slabs (HCS) are pre-stressed concrete elements, normally supported by steel or reinforced concrete/pre-stressed concrete beams. Studies have shown that the deflection of the supporting beam may be the reason for decreased shear capacity of the HCS, leading to premature failure of the HCS. Since shear tension failure is a common failure in HCS, there is a need for measures to prevent damage. There are measures to increase the shear capacity of the HCS which have been tested in experiments by other researchers, which will be discussed in this thesis.
When the supporting beam deflects, it also leads to a corresponding rotation in the connection zone. Cracks may appear in the connection as a result of this, and in addition with shrinkage and creep in the concrete, large cracks may form and damage the above flooring. Brittle flooring material, such as ceramic tiles, easily crack when there is movement and cracking in the structure underneath. Calculations will be done to analyze different measures to decrease the cracking in the connection joints, and measures to limit the rotation in the support zone. The results will be compared and analyzed to see the effect.
Steel fiber reinforced hollow core slabs have shown in studies, done by other researchers, promising result when it comes to controlling the damages resulting from deflection in the supporting beam. Since the HCS does not have shear reinforcement, the steel fibers would act as shear reinforcement. Using fiber in the HCS also increased the flexural strength.
Filling the voids with concrete have shown in studies not to have as good effect as hoped, being a questionable solution according to some studies.
When using brittle flooring materials in hollow core slab flooring systems, it is recommended from calculations to use smaller spans, continuous supporting beams and thin HCS to reduce rotation due to deflection of the supports. Adding extra reinforcement in the connection joint has shown to be a good solution to control cracking. Normally reinforcement is not placed in the connections to control cracking, however, results from calculations have shown this measure have a positive impact on the crack width calculations, by decreasing the cracks up to 21,9%. | |
