Paper by PERNETTI from ISCR 8th 1998 Lisbon Portugal
The concrete pavements, being subjected to thermal gradients, gravity and traffic loads, are itol in contact everywhere with their support. The traditional calculation methods use mathematical expressions developed assuming the slabs completely in contact with the support or expression not considering the presence of gravity load and thermal gradients with traffic loads at the same time. The maximum bending stresses rcsulting from these methods have generally a bad apprnximation with the ones evaluated by a non-linear structural analysis taking into account the loss of the contact. The difference may be higher than 30%. In this paper, it is first examined how the stress level increases with the support stiffness and then it is shown a simplified method which allows a good approximation. This method doesn't need any non-linear analysis but only a simple series of calculations which can be easy organized in a software or in a spreadsheet. A further advantage of the method is that it gives the maximum bending stress for many support stiffness at the same time, hence it allows to evaluate the influence of this factor too. The maximum error obtained, compared with the stress level yielded by the non linear FEM, is almost withiii 10%.