Page 44 - ICJ Jan 2023

TECHNICAL PAPER COLLECTOR’S EDITION

Fig 11 Beam B at failure
4
Fig 8 Load-deflection curves CONCLUSIONS
The following conclusions are drawn from the
investigation :

(i) Large web openings can be accommodated in
post tensioned prestressed concrete T-beams
while maintaining their full strength. At the
same time the serviceability requirements can
also be satisfied.
The test results clearly indicate the failure
Fig 9 Effect on ultimate load of reinforcement around
openings loads in beams with web openings are of the
same order as those of solid beams.
(ii) Post-tensioned prestressed concrete T-beams
with large web openings behave similarly to a
Vierendeel panel.
(iii) Shear concentration exists around the
openings
(iv) Beams having openings in high moment
region behave better than the beams having
openings in shear span. The ultimate moment
Fig 10 Effect on ultimate load of position of opening capacity of the former is also larger.

TABLE 2 Principal test results.
Specimen Cracking stage Ultimate stage P um Type of TPercentage Percentage
failure ultimate ultimate
Lo.cation Cracking Ultimate Location P cr load load as
of load load with solid per IS code
first crack P cr P um beam

B 1 Opening 3.5 7.5 Opening 2.1 Shear 83 119
(9.1)* secondary (100)*
hinging
mechanism

B 2 Opening 4.5 7.5 Midspan 1.7 Flexure 83 83

The Indian Concrete Journal | November 2018 45