1 Introduction
2 Research Significance
3 Net Tensile Stress Limit for PSC Members at Service Loads
4 Parametric Study for Estimation of Net Tensile Stresses of PSC Members at Service Loads
4.1 Variables for Parametric Study
Section of type | Details of sectiona | Tensile strength of strand (f
pu
, MPa) | Yield strength of reinforcing bar (f
y
, MPa) | Effective prestress ratio (f
pe
/f
pu
) | Reinforcing index (ω) | PPR (%) |
---|---|---|---|---|---|---|
Rectangular | 12RB16 16RB40 | 1860 (Grade 270) | 420 (Grade 60) 550 (Grade 80) | 0.5 0.55 0.6 0.65 | 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 | 50 67 100 |
Number of rectangular sections: 432 | ||||||
Tee | 12T16 16T40 | 1860 (Grade 270) | 420 (Grade 60) 550 (Grade 80) | 0.5 0.55 0.6 0.65 | 0.0135 0.027 0.0405 0.054 0.0675 0.081 0.0945 0.108 | 50 67 100 |
Number of T sections: 384 | ||||||
Inverted Tee | 28IT20 40IT52 | 1860 (Grade 270) | 420 (Grade 60) 550 (Grade 80) | 0.5 0.55 0.6 0.65 | 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 | 50 67 100 |
Number of inverted T sections: 432 | ||||||
Total number of analyses: 1248 |
4.2 Stress Estimation of Prestressing Strands in PSC Members Under Service Loads
5 Analysis Results of the Parametric Study
5.1 Rectangular Sections
5.2 Flanged Sections: Inverted T (IT) and T Sections
5.3 Effects of Tension Stiffening and Section Size
6 Proposed Approaches
6.1 Simple Checking of the Net Tensile Stress
Section shapes | PPR 100% (∆f
ps
≤ 250 MPa) | Partially prestressed concrete members (PPR ≥ 50%) | ||
---|---|---|---|---|
f
y
= 420 MPa (for ∆f
ps
≤ 250 MPa) | f
y
= 550 MPa (for ∆f
ps
≤ 250 MPa) | f
y
= 550 MPa (for ∆f
ps
≤ 350 MPa) | ||
R | 0.50 f
pu
| 0.50 f
pu
| 0.55 f
pu
| 0.50 f
pu
|
T | 0.50 f
pu
| 0.50 f
pu
| 0.60 f
pu
| 0.50 f
pu
|
IT | 0.50 f
pu
| 0.50 f
pu
| 0.50 f
pu
| 0.50 f
pu
|