a[mm]/l - Memorial University of Newfoundland DAI

failure IS ductile shear fatlure or shear failure with ducul~ty. Thln type of fmlure Ir aeuc
of transttlon between pure punchmg and pure flexure failures.
As mentioned ~n the Sccuan 4 1, all rpeccmens failed under duct~le she= fallure.
Thlr falure can be calegonzed under the thlrd type of failure. The Impact punching lmd
~ncreased nr the concrete-strength mereased and the steel re~nfarcement ratlo tncreued.
The fxlum rurf3ee of nomc of the rested rpclmcnr were csrrful!y removed and
eliamtned. The observed angler of failure surface had some vanallon. Far normal-
sirength concrete plates. the observed angle of falure surface war about 60 de~ee. wh~le
for hlgh-smngth concrete plates. !he angle war found lo about 65 depe. In addmon. Le
punching shear radius on the tenstan face happened a a dtrrance of (1 6-2.0) rlrncr the
plate depth (dl fmm the edge of loaded urrn for most of the tested rpeflmcns compared to
a dtnance d/Z for nasc load~ng.
4.6. Effect of Concrete Strength
The dertpled FompEsSlve strength targea for rhtr Inveseea!on were 35 MPil for narmdl-
strength and 80 MPP for hlgh-strength concrete as described ~n secllon 3.1. Increnang the
concrete compresswe rmngth fmm normal-strength to hlgh-smngth concrete mcre~sed
the energy abrorpl~an capac#ty, cntlcvl velocity of perforelon. and deflecaon al the
centerof speclmenr.
The energy absorption capnclty increaxd by nnge of about 3-5 smn, whdc the
cnrscal velas~ty of perfmuon nncreaxd by a range of about 20-30 percent. The
displacements st the center of spclrnm also increased amund twlu. This obrervntlon
nndicated that high-rmngth conerrre can pmvide higher ducrlltty for concrete plater.