Ingeniería e Investigación (Jan 2007)
A new method for designing floor slabs on grade due to the difficulty of applying simplified design methods, amongst them being the Portland Cement Association (PCA) and Wire Reinforcement Institute (WRI) methods
Abstract
This article presents a methodology for designing slabs on grade for industrial floors where there is an eccentricity between the slab centroid and the gravity centre loads of the loaded axle of forklift trucks travelling over the floor. An example was used for analysing how Portland Cement Association (PCA) and the Wire Reinforcement Institute (WRI) methods are inadequate for designing floors sublected to this condition. The new proposal for designing slabs on grade for industrial floors has been called the Camero method. An example of an industrial floor designed to be capable of sustaining an infinite number of load applications (or 50-year life) was compared to the results of the Camero method and PCA and WRI’s simplified methods. Industrial floors should be capable of sustaining an infinite number of load applications (50-year life) if designed with the Camero method; on the other hand, if designed using PCA and WRI methods they will only last one year (in this example the number of axle load applications in a 1-year period was equal to the number of allowable repetitions) because they will not be able to sustain an infinite number of load applications. It was concluded that designing plain concrete slabs (without reinforcement) on grade according to PCA and the WRI methods leads to slab fatigue, even though extreme fibre stress should not exceed 50 percent (50%) of static modulus of concrete rupture and slabs should sustain an infinite number of load repetitions (infinite amount of forklift truck traffic) were considered parameters in their design.
