Bridges & Structures

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

3. Flow Charts

Shear Design - Alternative 1 Flow Chart Text, Assumed Angle theta

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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 shear crack inclination angle theta (Design Step 5.7.2.5)
7. Calculate Epsilon x using Eq. S5.8.3.4.2-1
8. Is assumed value of theta greater than the value determined based on calculated Epsilon x?

NO - Use the value last determined for theta and go back to 7

YES - go to 9

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

YES - Use the value last determined for theta and go back to 7

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 and 5.7.2.4)
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?

NO - Provide additional longitudinal reinforcement and go to 12

YES - go to 18

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

END.

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