Dear Mudfarmer,
One other publication which might be of some help to you
is by the Association of Iron and Steel Engineers, the
AISE No. 6 specification for cranes. It is not a design
text but a set of specifications for cranes being designed
for steel mill duty. I have an old copy but the structural
aspects in it are probably along the lines of what you are
looking for. There is an example in the book which details
the design of a double girder crane girder. It is very
detailed. There are also the publications from the
Crane Manufacturers Association of America, Nos. 70 & 74
which would have some detail on the structural design of
cranes. Again, the AISE No. 6 and CMAA Nos. 70 & 74 are
specifications for crane design and not design texts. I am
not aware of any specific texts which deal exclusively
with crane design. I work for a crane manufacturer and
I am not aware of any special reference texts in the office.
I hope this helps you. I am sorry I do not have any
other resources to help you.
Good luck.
Irishengineer