PROBLEM. The joist (double tee) is to be used on a simply supported span of 8-m and is pre- tensioned with an initial force of 1,240 kN from low-relaxation strands. The centroid of the strands is located at 220-mm below the neutral axis of the DT throughout the beam span. Loss of prestress of service loads is 20%. Total uniformly distributed loads on the joists are: Dead Load = 4.5 kPa (beam weight included) and Live Load = 3.6 kPa. Compute the resulting stress at bottom fibers at DT at midspan due to service loads and prestress force. %D Section properties of the double tee joists (DT) shown as follows: • a = 2.4 m Yt = 103 mm Уь 3D 303 mm • A = 2.1 x 105 mm2 • | = 2.76 x 109 mm4 • Concrete unit weight = 24 kN/m3 %3D %3D %3D %D a=2.4 m N.A.
PROBLEM. The joist (double tee) is to be used on a simply supported span of 8-m and is pre- tensioned with an initial force of 1,240 kN from low-relaxation strands. The centroid of the strands is located at 220-mm below the neutral axis of the DT throughout the beam span. Loss of prestress of service loads is 20%. Total uniformly distributed loads on the joists are: Dead Load = 4.5 kPa (beam weight included) and Live Load = 3.6 kPa. Compute the resulting stress at bottom fibers at DT at midspan due to service loads and prestress force. %D Section properties of the double tee joists (DT) shown as follows: • a = 2.4 m Yt = 103 mm Уь 3D 303 mm • A = 2.1 x 105 mm2 • | = 2.76 x 109 mm4 • Concrete unit weight = 24 kN/m3 %3D %3D %3D %D a=2.4 m N.A.
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
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Transcribed Image Text:PROBLEM. The joist (double tee) is to be used
on a simply supported span of 8-m and is pre-
tensioned with an initial force of 1,240 kN from
low-relaxation strands. The centroid of the
strands is located at 220-mm below the neutral
axis of the DT throughout the beam span. Loss
of prestress of service loads is 20%. Total
uniformly distributed loads on the joists are:
Dead Load = 4.5 kPa (beam weight included)
and Live Load = 3.6 kPa. Compute the resulting
stress at bottom fibers at DT at midspan due to
service loads and prestress force.
Section properties of the double tee joists (DT)
shown as follows:
. а 3 2.4 m
• Yt = 103 mm
. Уь %3D 303 mn
• A = 2.1 x 105 mm2
| = 2.76 x 109 mm4
Concrete unit weight = 24 kN/m3
%3D
a=2.4 m
N.A.
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