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a[mm]/l - Memorial University of Newfoundland DAI
a[mm]/l - Memorial University of Newfoundland DAI
a[mm]/l - Memorial University of Newfoundland DAI
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mregnnng the complete tensfle stress.cnck openxng d~rplacement or crack wtdth such us<br />
follow:<br />
G, = 1;. f, dw<br />
where. Gf = fracturemergy requored to form an unit area<strong>of</strong> crack surface<br />
1, = ten~lle nress. rr r Rnctton <strong>of</strong> r,<br />
b,. = crack wtdth<br />
u, = enck width when f, wilehcs zem.<br />
(2.12)<br />
More co<strong>mm</strong>on an the descnptton <strong>of</strong> englnccnng maanal. the cxpmrion for GI<br />
cun be arnnged and expressed a% ;l funaton <strong>of</strong> a stress-$tram Inw. Thus. Wf Is defaned ar<br />
the fracture energy dennty. or work per unit volume. d~ssopated by cnck~ng. cdn be<br />
expressed rr<br />
where. f, = rcnsllc rrressexprerred on lcrms <strong>of</strong> tcnrlle slnln<br />
~r, = wtdlh <strong>of</strong> the fracture praccrs zone<br />
E, = tenslb stram<br />
(2 23)<br />
emax= martmum tensnle st<strong>mm</strong> when f,reaeher zero at the end <strong>of</strong> the tenslo"<br />
r<strong>of</strong>tenlng bnnch.<br />
As repaned by Marrouk and Chen (IW5). the fracture energy <strong>of</strong> high-nrength<br />
concrete 13 sbout five ttmcr he area under ascendtng ponton <strong>of</strong> its complete stress-rtnnn<br />
curve. Fraaum energy 8s ertmawd about tm times the ;ma under ascending ponion <strong>of</strong> 11%<br />
complete rtress-stmn curve for normal-mgth concrete as repomd by Mass~coue. Elwl.
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