Fall and Rise: The Story of 9/11: A gripping biography of triumph over tragedy

by Mitchell Zuckoff

as upper-floor survivors called for help, and as firefighters rushed inside, the South Tower experienced ominous structural changes. Shortly after 9:30 a.m., bursts of smoke spouted from the building’s north side, on the 79th and 80th floors, possibly from shifting floor slabs or the sudden ignition of pools of unspent jet fuel. Simultaneously, threats to the building’s integrity worsened. Intact core columns strained under the added burden previously borne by the severed columns. External columns on the tower’s east side supported added loads that had shifted from the severed columns. The remaining external columns also struggled to hold up sagging floors. The strain caused the exterior columns to bow inward, like straws trying to support a brick. All the while, unchecked fires undermined the strength of steel columns throughout the impact zone, contributing to a threat that almost no one imagined. The South Tower neared its breaking point.