Even with a thousand pounds of explosives?
My military engineer's "gut feeling" says "No".
The problem is that you need
high explosives to
cut steel which demands close contact because the cutting power falls of rapidly with distance away from contact. And the cutting level blast of HE ditto falls off rapidly - same thing stated in reverse.
So at even closest truck bomb distance you are relying on general overpressure blast which is the range where lower explosives - quarrying stuff like ANFO - come into their own. BUT they need surface area to act on and large truck load bombs of ANFO would certainly remove the "wall area" by blowing out panelling - even concrete partitions, floors. ceilings and the like. BUT it would not DIRECTLY
cut columns. Maybe tear out a column or two due to the "sail area" of partition wall dragging a column out - probably failing in shear at connections. BUT the structural redundancy of the "Nest" of columns would load redistribute without overall failure.
Then - and especially clear with WTC Twins - it would probably take simultaneous failure of both core and perimeter. And WTC design says that EITHER by itself would not be enough. Remember we are only dealing with a few columns in a concentrated area either core or perimeter IF we have even a well placed single truck bomb...and BOTH core and perimeter if we had TWO well placed truck bombs. AND that is so whether using HE or LE.
My money would be on the Towers surviving.
Again reversing the scenario - If I was the Military Engineer tasked by the General to demolish either or both "Twins" no way would I consider even
two well place truck bombs as my plan. Remember most Generals want guaranteed results. ***
....and as a Military Engineer Captain I don't want to spend what may be left of my Military career counting blankets in a stores battalion as the FORMER engineer officer who failed to demolish the WTC Towers.
(*** An anecdote from RL. About 30 years back the AU Army was rewriting its "Pamphlets" - the "Manuals of Warfare" - and me - Army Reserve officer (Engineers) - was in my Civvy street job in charge of the largest water supply dam in AU. So I was consulted on "how would you blow up this dam?"
I said "I wouldn’t try because it cannot be done by either conventional or non-conventional (including terrorist) war-like activity. Anything short of Nuclear". They had in mind a "Dam Busters" style scenario . Wrong sort of Dam. Details if anyone interested.
BUT the relevant issue here in this thread is that I suggested to back off and re-examine what the objective is...
...and they didn't need to blow up the dam to achieve it.
So ask what was the Terrorist objective in such an attack...and can it be achieved by other means. 'Coz
two truck bombs would not IMNSHO have collapsed one of the WTC Twins)