…the difference in the melting point of steel and the burning temperature of jet fuel as proof that the World Trade Center could not have fallen from the aircraft fires. What those authors fail to note is that while steel melts at around 1,370°C (2500°F) it begins to lose its strength at a much lower temperature. The steel structure of the World Trade Center would not have to melt in order for the buildings to lose their structural integrity. Steel can be soft at 538°C (1,000°F) well below the burning temperature of jet fuel.
https://education.jlab.org/qa/meltingpoint_01.html