An experimental program was conducted to monitor the development of strains and cracking in large-scale concrete slabs reinforced with GFRP bars that experience drying shrinkage under ambient conditions. Six slabs reinforced with two types of GFRP bars, namely ribbed and sand-coated with different spacing (200 mm and 300 mm), a slab reinforced with steel bars, and a plain slab were cast on lean concrete layer 100 mm thick laid over compacted soil. This paper presents the development of a numerical model for the slab subjected to drying shrinkage under ambient conditions. The developed finite element model of the slab on grade predicted with reasonable accuracy the evolution of environmentally induced stresses and cracking in the concrete slab. Parametric studies were performed with the validated FE model to investigate the effect of parameters such as concrete strength, bar diameter and slab thickness.