IMPACT RESISTANCE OF PLAIN, REINFORCED AND PRESTRESSED CONCRETE BEAMS

A new and larger testing machine was built capable of taking beams of span up to 54in. Strikers of three different weights were used with centrepoint and two-point symmetrical loading systems. An extensive range of reinforced concrete beams was tested and the results of the various measurements were analysed. Conclusions are reported. A new method of analysis to permit the computation of equivalent static loads was developed. The method, called the Area-Energy method assumes that for the duration of one impact the moment of inertia and elastic modulus are constant but makes no assumptions about the variation of these quantities from one impact to the next. The method is also applicable to impact tests on steel bars, etc. Findings suggest that the amount of top steel necessary to prevent cracking on the top face of beams due to vibration is independent of the striker weight and that the amount provided need not exceed half the amount of bottom steel. (Author)