thats what im saying, in order to warp they have to deteriorate in some way. Melting doesn't neccisarily mean the whole place turned to liquid just partially liquified and deformed and thats what they were trying to disprove that jet fuel couldnt make the structure fall.
When the WTC was constructed, the I-Beams were coated in a Fire Retardent Foam, this was to protect the steel from being overexposed to heat from a fire. It was believed that the impact of the plane crashes caused the protective foam to come of, leaving the I-Beams vulnerable to fire.