This is why Donald Trump thought the WTC buildings should not have collapsed. He built his buildings better. They were NOT built according to the newer 1968 code which allowed lighter construction of the WTC,with much less concrete, and unfortunately, much less fireproofing, but by the older code.
Following are quotes from: Deputy Fire Chief Vincent Dunn ret.
Donald Trump in New York City has constructed the tallest reinforced concrete high-rise residence building.The structures that limit and confine fires best, and suffer fewer collapses are reinforced concrete pre WWII buildings such as housing projects and older high rise buildings like the empire state building,
The more concrete, the more fire resistance; and the more concrete the less probability of total collapse. The evolution of high- rise construction can be seen, by comparing the empire state building to the WTC. My estimate is the ratio of concrete to steel in the empire state building is 60/40. The ratio of concrete to steel in the WTC is 40/60.
The Empire State Building in my opinion, and most fire chiefs in New York City, is the most fire safe building in America. I believe it would have not collapsed like the WTC towers. I believe the Empire State Building, and for that matter any other skeleton steel building in New York City, would have withstood the impact and fire of the terrorist’s jet plane better than the WTC towers.
The tallest building in the world, the Petronas Towers, in Kula Lumpur, Malaysia, is more like the concrete to steel ratio of the empire state building than concrete to steel ratio of the WTC.
Builders hailed the New York City building code of 1968 as a good performance code. However, some fire chiefs decried it as a law that substituted frills for real construction safety.
The WTC started construction in the 1970s. And the WTC towers built by the Port Authority of New York did not have to comply with the minimum requirements of the new 1968 performance building code.
If you look at the WTC rubble at ground zero you see very little concrete and lots of twisted steel.The most noticeable change in the modern high-rise construction is a trend to using more steel and shaping lightweight steel into tubes, curves, and angles to increase its load bearing capability. The WTC has tubular steel bearing walls, fluted corrugated steel flooring and bent bar steel truss floor supports.
To a modern high rise building designer steel framing is economical and concrete is a costly material. For a high-rise structural frame: columns, girders, floors and walls, steel provides greater strength per pound than concrete.
Concrete is heavy. Concrete creates excessive weight in the structure of a building. Architects, designers , and builders all know if you remove concrete from a structure you have a building that weights less.So if you create a lighter building you can use columns, girders and beams of smaller dimensions, or better yet you can use the same size steel framing and build a taller structure.
In New York City where space is limited you must build high. The trend over the past half-century is to create lightweight high buildings. To do this you use thin steel bent bar truss construction instead of solid steel beams. To do this you use hollow tube steel bearing walls, and curved sheet steel (corrugated) under floors.
To do this you eliminate as much concrete from the structure as you can and replace it with steel. Lightweight construction means economy. It means building more with less. If you reduce the structure’s mass you can build cheaper and builder higher.
Unfortunately unprotected steel warps, melts, sags and collapses when heated to normal fire temperatures about 1100 to 1200 degrees F.