| ABSTRACT: | THE ACTIONS OF AXIAL LOADS ON MASONRIES – ULTRASONIC
VERIFICATION AND STATISTICAL ANALYSIS OF OBTAINED DATA
G. Ferrari, and M.Pugliese
CNR ITC, Milano, Italy.
Among the different non-destructive tests used to carry out an exhaustive survey about the
mechanical characteristics of a masonry made of solid -bricks, the ultrasonic method has
experienced a wide diffusion thanks to its low costs and to its easiness of use; the method
essentially consists in detecting the propagation velocity of ultrasonic pulses propagating
through a solid to be acoustically characterized. The solid considered in this theoretical and
experimental survey has been obtained from a meaningful statistical sample of masonry units
made of solid - bricks bound together by cement mortar.
The experimentation made use of two sets of masonry panels, prepared for this purpose,
consisting of solid bricks, arranged according to the thickness (set A) or according to a “two-
head”, gothic pattern scheme (set B).
The total height of the samples of the two sets are 48 and 96 cm respectively, inclusive of
cement mortar beds, the mortar having been prepared according to the Italian regulations
The issues which came out during the statistical analysis of the experimentation results are
basically of inductive nature: the purpose is to move from a limited and incomplete knowledge
of the values of the propagation velocity quantity measured on the masonry, to get the most
suitable definition of the possible distribution of all the values that can be reached by velocity
under stress conditions imposed by the strength applied on the masonry at the moment of
measuring the ultrasonic wave. The strength is generated by a press used to simulate the
conditions imposed on the axial strength of the specimens under investigation.
The purpose of this work is to present a procedure for the interpretation of the data in order to
assess the compressive tensile state by using the ultrasonic velocity variable obtained from
masonry samples expressly prepared for this experiment.
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