Is there any reference material or charts for predicting the rate of corrosion for various steel including zinc plated steel under different environments (moisture, de-icing salt, salt air from the sea…)?
I don't believe any reference covers every steel, with and w/o every possible coating, in every environment (especially stairs that are walked on!).
Suggest 'Corrosion of Carbon and Alloy Steels,' pp. 5-53 in ASM Handbook, Volume 13B, Corrosion: Materials, (2005), especially 'Corrosion of Metallic Coated Steels,' pp. pp. 35-39.
Or, see pp. 509-582 in the previous edition, ASM Handbook, Volume 13, Corrosion (1982).
ASTM B633, "Standard Specification for Electrodeposited Coatings of Zinc on Iron and Steel," gives some average corrosion rates for zinc coatings in different atmospheres.
For industrial atmospheres: 5.6 microns/year,
For Urban non-industrial or marine atmospheres: 1.5 micron/year.*