Structural bolts are typically grade 8.8 to AS/NZS1252.
Most hot rolled shapes are specified as grade 300 material, actual yield strength depends on the thickness of web/flange, etc.
CHS/SHS/RHS are typically grade 350, 350MPa yield strength. Some can be sourced in dual grade 450MPa material (usually smaller sizes). This complies with all the material limitations of grade 350 but has a higher yield strength.
Welded sections, plates can be anything you want, typically fabricated from grade 300/350 to 400 plate.
Lookup standards AS/NZS3678 & AS/NZS3679 & AS/NZS1163.
The Australian steel code has a table in it denoting the typical material grades and subgrades that comply and relevant standards. There is no direct comparison to American grades/sections unfortunately.
If its a project supplying American sections to Australia be aware it may not comply without testing and qualification by a suitability qualified metallurgist. Until that is undertaken it would be treated as unidentified steel, look that up in AS4100 for definition. Basically you'd be better using a local fabricator and supply chain. I've been involved in a few foreign steel supply substitutions and it never works out to be plain sailing.
AS & NZ standards are based on Australian/New Zealand fabricated plate and sections. Some substitutions for different international standards are provided for Japanese and British and European material/grades/codes.