Drying shrinkage can be a major cause of deterioration for concrete structures,where the deformation of calcium silicate hydrate (C-S-H) gel is a key issue.It is quite chanlenging to investigate the drying behavior of C-S-H because of its small size and test limitations.This paper presents a numerical model for predicting the drying shrinkage of C-S-H gel including low density (LD) and high density (HD) C-S-H.From previous models and experimental evidence from literature, the nanostructure model of C-S-H is introduced as an assemblage of discrete granular particles at nanoscale.In this paper,the virtual nanostructures of LD and HD C-S-H are generated as packing of spherical particles.From the nanostructure model, pore structure characteristics are analyzed.At mid to high relative humidity, changes in capillary pressure is assumed as the governing mechanisms for drying-induced shrinkage.Based on the virtual nanostructures of LD and HD C-S-H, their drying shrinkage are respectively predicted by a three-dimensional lattice model.It is found that the shrinkage of C-S-H is approximately inversely proportional to RH in the range of 45%RH and 100% RH.Simulations also indicate that the shrinkage ofLD C-S-H is larger than that of HD C-S-H.