One interesting point some "truthers" make is that the welded steel lattice frame of the buildings should have been an efficient heat sink transfering heat away

One interesting point some "truthers" make is that the welded steel lattice frame of the buildings should have been an efficient heat sink transfering heat away from hotter areas to colder areas. So warpage is unlikely to have been significant. On the other hand thermal expansion of relatively straight beams is likely what brought the towers down.