Blast Loading of Structures in the Regular Reflection and Low Mach-Stem Regions.

摘要

An investigation was made of the blast loading on model structures in the regular reflection region and in the region where the height of the Mach stem varies from less than the structure height to several times the structure height. The three structure models employed were 2 x 2 feet in cross section, with lengths of 2, 4, and 18 feet. They were subjected to blast waves from 250- pound charges of TNT detonated at heights of 38, 64, and 90 feet above the surface. When scaled to nuclear burst, these conditions represent a 7-story building subjected to a 20-kt burst. They therefore constitute a situation involving multistory structures. Variations from two-dimensional theory for predicting the pressure loading on the front surface were observed for small zenith angles while variation on the top surface was observed at large zenith angles. Shortening of the positive-pressure duration on the front surface was found to occur in the regular reflection and low Mach-stem regions. The measured times of occurrence for maximum average pressure on the rear face of the 2- x 2- x 18-foot target are in good agreement with times predicted.