Could you please rebut the salient points from General Partin's research below to buttress your contention that a single ANFO bomb was the cause of the damage?
The media and the Executive branch reported that the sole source of the devastation was a single truck bomb consisting of 4,800 pounds of ammonium nitrate, transported to the location in a Ryder Truck and parked in front of the building. It is impossible that the destruction to the building could have resulted from such a bomb alone.
To cause the damage pattern that occurred to the Murrah building, there would have to have been demolition charges at several supporting column bases, at locations not accessible from the street, to supplement the truck bomb damage. Indeed, a careful examination of photographs showing the collapsed column bases reveals a failure mode produced by demolition charges and not by a blast from the truck bomb.
To understand what caused the damage to the Murrah Building, one needs to understand some basics about the use and nature of explosives.
First, blast through air is a very inefficient energy coupling mechanism against heavily reinforced concrete beams and columns.
Second, blast damage potential initially falls off more rapidly than an inverse function of the distance cubed. That is why in conventional weapons development, one seeks accuracy over yield for hard targets. That is also why in the World Trade Center bombing (where the only source of blast damage was a truck bomb) the column in the middle of the bombed-out cavity was relatively untouched, although reinforced concrete floors were completely stripped away for several floors above and below the point of the bomb's detonation (see Time Magazine, 3-8-93, page 35).
By contrast, heavily reinforced concrete structures can be destroyed effectively through detonation of explosives in contact with the reinforced concrete beams and columns. For example, the entire building remains in Oklahoma City were collapsed with 100-plus relatively small charges inserted into drilled holes in the columns. The total weight of all charges was on the order of 200 pounds.
The detonation wave pressure (1,000,000 to 1,500,000 pounds per square inch) from a high detonation velocity contact explosive sweeps into the column as a wave of compressive deformation. Since the pressure in the wave of deformation far exceeds the yield strength of the concrete (about 3,500 pounds per square inch) by a factor of approximately 300, the concrete is turned into granular sand and dust until the wave dissipates to below the yield strength of the concrete. This leaves a relatively smooth but granular surface, with protruding, bare reinforcement rods__a distinctive signature of damage by contact explosives. The effect of the contact explosive on the reinforcement rods themselves can only be seen under microscopic metallurgical examination. (The rods are inertially confined during the explosion and survive basically in tact because of their much higher yield strength and plasticity.)
When a reinforced concrete structure is damaged through air shock coupling and the pressure is below the compressive yield strength of the concrete, the failure mode is generally compressive structural fracture on one side and tensile fracture on the other__ both characterized by cracks and rough fracture surfaces. Such a surface texture is very different from the relatively smooth granular surface resulting from contact explosives.
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[The graphic] shows the architectural layout of the first floor of the Murrah Building and the location of the truck bomb with superimposed circles of roughly equal levels of damage potential. The explosive force drops rapidly (initially proportional to one over the distance cubed) as the shock front travels farther and farther away from the truck bomb. After the release wave, the shock front will propagate proportional to one over the distance squared. The maximum possible yield from 4800 pounds of ammonium nitrate would be obtained if it were in a compressed sphere and detonated from the center. That would produce a 4.4 foot diameter sphere of detonation products at about 500,000 pounds per square inch. By the time the blast wave hits the closest column, the pressure would have fallen off to about 375 pounds per square inch. That would be far below the 3500 pound compressive yield strength of the concrete. Any column or beam failure from the truck bomb would therefore have been from blast wave structural loading and not from any wave of deformation in the concrete. The basic building structure consists of three rows of columns (35 feet apart) with eleven columns in each row (20 feet apart). The four corner columns have an external clamshelllike structure for air ducts, etc. If we label the column rows A, B. and C from front to back, and number the columns 1 through 11 from left to right, then columns A2, A3, A4, A5, A6, A7, A8, and B3 collapsed, essentially vertically. Tab 2 shows a very large reinforced concrete header at the floor level of the third floor of column row A. Much larger columns extend from the header down for the odd-numbered columns, i.e., A3, A5, A7, and A9. The even- and odd-numbered columns extended from the top of the building down to the header. The foundation of the building is a heavy, reinforced concrete slab with no sub-levels. From the potential damage contours on [graphic], and assuming the single truck bomb, the pressure and impulse for collapsed columns B4, B5 and A7 are all in the 25 to 35 pounds per square inch region. However, the much smaller and closer columns, B4 and B5, are still standing, while the much larger column A7 is down. Column B3 is down with 42 percent less pressure and impulse than columns B4. These facts are sufficient reason to know that columns B3 and A7 had demolition charges on them. Moreover, there is not sufficient blast impulse at that range to collapse any of the three. In fact, columns B2, B4 and Bs all have the sheet rock and furring strip finish still intact on the second and third floors except where damaged by falling debris. The large header across the front of the building at the third floor of Row A was not blown back into the building as one may expect from such a large bomb. The header came straight down but rolled backward 90 degrees because the columns above the header rested off center toward the back.