What's the likelyhood

In the last couple of weeks I watched several movies. One of which was
"The Core", the basic premise of which is that the Earth's core stopped
rotating, which of course, got the Earth's magnetic fields in a bit of a
snit. So this mob of scientists sets off to the core so as to get it
rotating again.

The part I'm actually interested in is: At one stage the magnetic field
has a hole in it which allows the cosmic radiation throug. A beam approx.
100 meters diameter (me guessing) which crosses the (I think Golden Gate
Bridge - don't know if there's anything similar) at 90deg.

In the time it takes for that beam to cross the bridge (~10-15 sec - movie
time) where the beam makes contact, the bridge melts & falls into the
drink (Yeah, nasty things happen to the people, & cars too - though
strangely not as bad - at least not shown).

What I am interested in is, the damage to bridge. Would it in fact have
melted? Certainly there would have been some damage, structural weakening
at the very least I imagine. If it makes a difference, the season
appeared to be late Spring/eraly Summer.