Discussion

“SOME PHOTOELASTIC EXERCISES IN RELATION TO MASONRY STRUCTURES”

Messrs. Thomas, Beam, Bret tell, Bright and James*

City of Birmingham Polytechnic

Reported by Mr. D.H. Mitchell, C.E.G.B.(Berkeley Nuclear Laboratories)

Dr. I.B. MacDuff (University of Stratholyde) asked if any cyolio loading tests had been carried out to see if the fringe pattern on the tension side of the beam disappeared under zero load conditions* If it persisted then he thought it should be possible to determine whether it indicated crack initiation or stress concentrations.

Dr, Hearn said that cyclic tests had been carried out and that, in the early stages at least, they had shown relaxation of the strains so that, initially, the fringes were indicative of increased strain level local to the mortar joint*