MaucJiester Meuioirs, Vol. hi. (191 2), Ah. 0. 



IX. On the modes of rupture of an open hemispherical 

 concrete shell under axial pressure. 



By J. R. GWYTHER, M.A. 



{^Comnmnicated by Mr. R. F. Gwyt/ier, M.A.) 



[Received and read 2jrd Janitary, igi3.) 



This paper is written to describe a io-w experiments 

 undertaken tentatively in the hopes of obtaining some 

 definite description of the circumstances and mode of 

 rupture as the load is increased, and it is the author's 

 intention to continue the investigation. The specimens 

 experimented on were made of concrete in the proportion 

 of I : i| : 2 of cement, sand and stone, the aggregate being 

 ^-inch granite chippings, and were carefully prepared in 

 wood moulds. After remaining in the moulds for seven 

 days, they were removed and allowed to set under water 

 for a month, and were finally tested four days after being 

 removed from the water. The specimens were then sub- 

 jected in the ordinary way to compression in a horizontal 

 testing machine with the results to be described. It 

 would perhaps have been preferable to have used a vertical 

 machine for the purpose, since when the load was not 

 removed sufficiently quickly on causing rupture, the 

 specimens were injured by the falling parts. 



The author wishes to express his acknowledgments to 

 Mr. J. H. Reynolds, the Principal of the Manchester 

 Municipal School of Technology, to Mr. Topplewell, and 

 to Mr. A. Herring-Shaw for permission to use the 

 laboratories and apparatus. 



Six specimens were made and tested, of three sizes 

 with two specimens of each, and at a later period three 



April 2gth, igi2. 



