if you introduce a tender-stemmed vine latish in the season, then yes, you will have some 'burn' problems- but what usually happens is that the plant goes 'ouch- you SOB, I'm gonna grow a callous right there' and comes back stronger for the encounter.

tough things like morning glories, or perennial vines like clematis, wisteria, climbing hydrangea...no problem. there are plenty of BLACK metal arbors out there, and under normal growing conditions, the arbors are covered- and therefor shaded- long before the heat becomes a problem.