Assessment of shear capacity of pre-stressed hollow core floor units in the local construction industry

Abstract

Pre-stressed, pre-cast hollow core slabs are used as transfer slabs in the local construction industry. The shear capacity of these structural units has a bearing influence on the performance of these elements as such, and is the basis of assessment in this research document. A case study of five manufacturers is undertaken to compare the safety envelope the manufacturers are working in with respect to the shear resistance of pre-stressed hollow core units. The safe-load tables are examined and values for shear force are evaluated for the given section and material properties, by means of EN1992 -1 -1 (2004) and F.I.P. recommendations (1998). It emerged that there is confusion in the interpretation of the tables and a lot of information regarding the product is lacking. The conclusions drawn from the experimental results are not conclusive because the number of samples tested as such is small in comparison to the variables involved. The pattern noted in the resulting Shear force - Displacement diagrams show that the results from the tests compare well with the code predictions. Further more the safe-load tables are found to be quoting very low values for shear capacity when compared to the code predictions and experimental results. In light of the introduction of the CE Marking in the near future, whereby it will be mandatory for the manufacturers to provide comprehensive technical documentation of the product, this study suggests that the values of the safe-load tables are brought closer to the actual predictions dictated by the code.