Bridges & Structures

Comprehensive Design Example for Prestressed Concrete (PSC) Girder Superstructure Bridge

3. Flow Charts

Shear Design - Alternative 2 Flow Chart Text, Assumed Strain ε_x

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1. Determine b_v and d_v Eq. S5.8.2.9 (Design Step 5.7.2.1)
2. Calculate V_p
3. Calculate shear stress ratio, v_u/f'_c (Design Step 5.7.2.2)
4. If the section is within the transfer length of any strands, calculate the average effective value of f_po (Design Step 5.7.2.5)
5. If the section is within the development length of any reinforcing bars, calculate the effective value of A_s (Design Step 5.7.2.5)
6. Assume value of Epsilon x and take theta and beta from corresponding cell of Table S5.8.3.4.2-1
7. Calculate Epsilon x using Eq. S5.8.3.4.2-1 (Design Step 5.7.2.5)
8. Is calculated Epsilon x less than assumed value?

NO - go back to 6

YES - go to 9

9. Is assumed value of theta too conservative, i.e., too high?

YES - go back to 6

NO - go to 10

10. Determine transverse reinforcement to ensure V_u <= Phi V_n Eq. S5.8.3.3 (Design Step 5.7.2.5)
11. Check minimum and maximum transverse reinforcement requirements S5.8.2.5 and S5.8.2.7 (Design Step 5.7.2.3)
12. Can longitudinal reinforcement resist required tension? Eq. S5.8.3.5 (Design Step 5.7.6)

NO - go to 17

YES - go to 13

13. Check bursting resistance (S5.10.10.1) (Design Step 5.7.4)
14. Check confinement reinforcement (S5.10.10.2) (Design Step 5.7.5)
15. Check horizontal shear at interface between beam and deck (S5.8.4) (Design Step 5.7.7)
16. Go to End
17. Can you use excess shear capacity to reduce the longitudinal steel requirements in Eq. S5.8.3.5-1?

YES - Choose values of theta and beta corresponding to larger Epsilon x, Table S5.8.3.4.2-1 and go back to 10

NO - Provide additional longitudinal reinforcement and go back to 12

END.

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