Post by shred on Apr 27, 2013 4:33:29 GMT -5
Compare:
911research.wtc7.net/wtc/analysis/compare/windsor.html
Compare to these extracts from investigation into Windsor Tower fire, by Professor Colin Bailey, Manchester University which contradicts their assumptions completely.
www.mace.manchester.ac.uk/project/research/structures/strucfire/CaseStudy/HistoricFires/BuildingFires/default.htm
Troofers don't know their backsides from their elbows.
Before examining the partial collapse of the Windsor building more closely, we note that steel-framed and steel-reinforced-concrete-framed structures behave very differently in fires.
Steel is a good conductor and concrete is a poor conductor of heat. Thus in a fire, a steel frame will conduct heat away from the hotspots into the larger structure. As long as the fire does not consume the larger structure, this heat conductivity will keep the temperatures of the frame well below the fire temperatures. The same is not true of steel-reinforced-concrete structures, since concrete is not a good thermal conductor, and the thermal conductivity of the rebar inside the concrete is limited by its small mass and the embedding matrix of concrete.
Fires can cause spalling of concrete, but not of steel. This is because concrete has a small percentage of latent moisture, which is converted to steam by heat. Thus, a large fire can gradually erode a concrete structure to the point of collapse, whereas a fire can only threaten a steel-framed structure if it elevates steel temperatures to such an extent that it causes failures.
Steel is a good conductor and concrete is a poor conductor of heat. Thus in a fire, a steel frame will conduct heat away from the hotspots into the larger structure. As long as the fire does not consume the larger structure, this heat conductivity will keep the temperatures of the frame well below the fire temperatures. The same is not true of steel-reinforced-concrete structures, since concrete is not a good thermal conductor, and the thermal conductivity of the rebar inside the concrete is limited by its small mass and the embedding matrix of concrete.
Fires can cause spalling of concrete, but not of steel. This is because concrete has a small percentage of latent moisture, which is converted to steam by heat. Thus, a large fire can gradually erode a concrete structure to the point of collapse, whereas a fire can only threaten a steel-framed structure if it elevates steel temperatures to such an extent that it causes failures.
911research.wtc7.net/wtc/analysis/compare/windsor.html
Compare to these extracts from investigation into Windsor Tower fire, by Professor Colin Bailey, Manchester University which contradicts their assumptions completely.
The Windsor Tower was completely gutted by the fire on 12 February 2005. A large portion of the floor slabs above the 17th Floor progressively collapsed during the fire when the unprotected steel perimeter columns on the upper levels buckled and collapsed (see Figure 1). It was believed that the massive transfer structure at the 17th Floor level resisted further collapse of the building.
The whole building was beyond repair and had to be demolished. The estimated property loss was €72m before the renovation.
Based on the footages of available media filming, Table 2 summarises the estimated time frame for the structural collapses of the Windsor Tower.
On the other hand, the reinforced concrete central core, columns, waffle slabs and transfer structures performed very well in such a severe fire. It is clear that the structural integrity and redundancy of the remaining parts of the building provided the overall stability of the building.
The whole building was beyond repair and had to be demolished. The estimated property loss was €72m before the renovation.
Based on the footages of available media filming, Table 2 summarises the estimated time frame for the structural collapses of the Windsor Tower.
On the other hand, the reinforced concrete central core, columns, waffle slabs and transfer structures performed very well in such a severe fire. It is clear that the structural integrity and redundancy of the remaining parts of the building provided the overall stability of the building.
www.mace.manchester.ac.uk/project/research/structures/strucfire/CaseStudy/HistoricFires/BuildingFires/default.htm
Troofers don't know their backsides from their elbows.