Little late to the party, but essentially Benton Partin (BG, USAF, Ret.) did his entire research by looking at photographs of the Murrah Building. However, he has no background whatsoever in structural engineering, structural mechanics, progressive collapse, or building failure. Consequently, his argument that it was impossible for certain columns to fail under blast was irrelevant given that the columns failed in the structural progressive collapse following the ONE column failure associated with the blast, column G20, closest to the explosion and failing through brisance. Also, his association with "blast research" ended in the 1970's - it would be interesting to see whether his similar calculations for St. Mary Axe and Bishopsgate prove that those also could not have failed in the blast...Interestingly, he also claimed that explosives were used at Waco - despite no evidence in that direction...