Let me give you some information that might be usefull.
One thing that you must understand, is weight bearing loads. WBL basically say that X floor can hold X weight. X floor exerts X amount of force on load bearing structure. If X floor (In this case, FLOORS) are compromised, than X floor caan only hold X weight.
Example. Take a stack of bricks. Not cinder blocks, but bricks. Walking stones are the best for this analogy. Stack them 15-20 tall. Put a small spacer on all four corners of each block before putting the next one on. Now, take a hammer and wack the top one fairly hard. I can almost GUARANTEE that your hammer will break every brick in the stack. This is basically what happened on 9/11. The floors below were only designed to safely hold X amount of weight. EVEN IF they could hold 50% more than the design pressure, they STILL couldn't hold up 25-30 floors above it. This would exceede its WBL by 3000% or more. Impossible to hold.
And as far as it slowing them down, nope. Not at all. When X floor recieved X load from 25-30 floors above, it failed. This in turn created MORE weight for the floor below it to try to absorb. It couldn't so it failed also. For instance. If it took (Not accurate just numbers for argument sake) floor 75 10 seconds to absorb 100 pounds of weight from above to the point of failure, then now floor 75 has not only 100 pounds of pressure from the inital fall, but also floor 75's weight. Now, because floor 74 has 110 lbs of weight, it would only take 9 seconds. See my drift?? Multiply that by millions of pounds of force, and you get casastropic failure.
Let me give you some information that might be usefull.
One thing that you must understand, is weight bearing loads. WBL basically say that X floor can hold X weight. X floor exerts X amount of force on load bearing structure. If X floor (In this case, FLOORS) are compromised, than X floor caan only hold X weight.
Example. Take a stack of bricks. Not cinder blocks, but bricks. Walking stones are the best for this analogy. Stack them 15-20 tall. Put a small spacer on all four corners of each block before putting the next one on. Now, take a hammer and wack the top one fairly hard. I can almost GUARANTEE that your hammer will break every brick in the stack. This is basically what happened on 9/11.
The floors below were only designed to safely hold X amount of weight. EVEN IF they could hold 50% more than the design pressure, they STILL couldn't hold up 25-30 floors above it. This would exceede its WBL by 3000% or more. Impossible to hold.
And as far as it slowing them down, nope. Not at all. When X floor recieved X load from 25-30 floors above, it failed. This in turn created MORE weight for the floor below it to try to absorb. It couldn't so it failed also.
For instance. If it took (Not accurate just numbers for argument sake) floor 75 10 seconds to absorb 100 pounds of weight from above to the point of failure, then now floor 75 has not only 100 pounds of pressure from the inital fall, but also floor 75's weight. Now, because floor 74 has 110 lbs of weight, it would only take 9 seconds. See my drift?? Multiply that by millions of pounds of force, and you get casastropic failure.