Lightweight Concrete for High Strength - Expanded Shale & Clay
Lightweight Concrete for High Strength - Expanded Shale & Clay
Lightweight Concrete for High Strength - Expanded Shale & Clay
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l<br />
d<br />
= l<br />
t<br />
+ l<br />
fb<br />
⎛<br />
= ⎜<br />
⎝<br />
f<br />
d<br />
⎞ ⎛ 6.4( f<br />
− 21⎟<br />
+ ⎜<br />
⎠ ⎝<br />
−<br />
pt b<br />
su<br />
4<br />
'<br />
'<br />
f<br />
c<br />
f<br />
c<br />
f<br />
se<br />
) d<br />
b<br />
26<br />
⎟ ⎞<br />
+<br />
⎠<br />
( A.25)<br />
l<br />
d<br />
= l<br />
t<br />
+ l<br />
fb<br />
⎛<br />
= ⎜<br />
⎝<br />
f<br />
d<br />
⎞ ⎛ 6.4( f<br />
− 5⎟<br />
+ ⎜<br />
⎠ ⎝<br />
−<br />
pt b<br />
su<br />
4<br />
'<br />
'<br />
f<br />
c<br />
f<br />
c<br />
f<br />
se<br />
) d<br />
b<br />
15<br />
⎟ ⎞<br />
+<br />
⎠<br />
( A.26)<br />
A.11.11 Barnes, Burns and Kreger, 1999<br />
Barnes, Burns and Kreger tested 36 AASHTO Type I normal weight HPC girders having<br />
release strengths from 4,000 to 7,000 psi and strengths at testing from 5,700 to 11,000 psi. All<br />
prestressing strands were 0.6-inch diameter Grade 270 ksi LOLAX strands in either a “bright” or<br />
“rusted” surface condition. Included in the test program were girders with fully bonded strands<br />
and debonded strands. One of the outcomes of the research program was Equation A.27 <strong>for</strong><br />
predicting development length.<br />
l<br />
d<br />
=<br />
5 ⎛<br />
⎜<br />
4 ⎜<br />
⎝<br />
f<br />
pt<br />
f<br />
'<br />
ci<br />
+ ( f<br />
ps<br />
−<br />
f<br />
pe<br />
) d<br />
⎟ ⎟ ⎞<br />
⎠<br />
b<br />
( A.27)<br />
A.11.12 Peterman, Ramirez, Olek, 2000<br />
Peterman, Ramirez, and Olek conducted research on HSLC bridge girders. Their<br />
research is the only other research known where HSLC girders using 0.6-inch diameter strands<br />
were tested. Their report indicated that all multiple strand specimens were rein<strong>for</strong>ced with<br />
sufficient stirrups to prevent web-shear cracking at the member ends. The prevention of shear<br />
cracking in the transfer region has been shown to result in strand slip causing premature shear<br />
failure.<br />
2.11.13 Kolozs, 2000<br />
Kolozs, under the supervision of Professors Ned Burns and John Breen, tested HSLC<br />
girders with strengths between 6,000 and 8,000 psi prestressed with ½-inch diameter Grade 270<br />
LOLAX strand. Kolozs found the current AASHTO equation <strong>for</strong> development length was<br />
conservative.<br />
A-23
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