The British Standard for live loads (BS 6399 Part 1) specifically states that the floor live load reduction also applies to "the design of columns, piers, walls and their supports and foundations".
Perhaps you could use this to persuade your reviewing engineer that it is not unreasonable for...
I have an old section book from the 1970's. This gives safe working loads for starred angles based on BS 449. The angle sizes vary from 50x50 angles up to 200x200 angles. It covers both mild steel and high yield steel. If you wish I could send you a copy.
Regards
An 8.8 bolt has an ultimate tensile strength of 80 Kg/mm2 (785N/mm2) and a yield strength of 80% x 80Kg/mm2 = 64 Kg/mm2 (628N/mm2)
Surely an allowable shear stress of 70% x ultimate tensile stress is much too high. This 550 N/mm2.
Generally, the shear stress is equal to 60% x yield stress...
Have a look at web site,
http://home.earthlink.net/~jimlux/radio/math/catenary.htm.
This gives formulae for horizontal and inclined catenaries.
Linslade
The 'new' section properties for angles can be found in BS EN 10056-1:1999. Specification for Structural Steelwork Equal and Unequal Angles. I believe that this was the old BS 4.
Regards