|
|
||
| Bridge Technology | |
|
|
|
FHWA >
Infrastructure >
Bridge >
LRFD >
Design Examples >
PSC (USC Units)
|
|||
| |||
| << Previous | Contents | Next >> |
| Method | Location | Girder | Slab, Haunch and Ext. Diaphragm | Parapets | FWS | Positive LL(3) |
Negative LL(4) |
|---|---|---|---|---|---|---|---|
| (ft.) | (k-ft) | (k-ft) | (k-ft) | (k-ft) | (k-ft) | (k-ft) | |
| Opis | 11 | 615.5 (1) | 649.8 (1) | 84.9 | 102.2 | 878.4 | - |
| Qcon | - (5) | - (5) | - | 114.0 | 909.3 | - | |
| Table 5.3 | 656.0 (2) | 643.0 (2) | 85.0 | 114.0 | 886.0 | - | |
| Opis | 55 | 1,709.5 (1) | 1,864.8 (1) | 163.4 | 196.6 | 2004.3 | - |
| QCon | - | - | - | 219.3 | 2,063.0 | - | |
| Table 5.3 | 1,725.0 (2) | 1,832.0 (2) | 164.0 | 220.0 | 2,010.0 | - | |
| Opis | ≈ 110 | 0 | 0 | -326.7 | -393.3 | - | -2,098.8 |
| QCon | - | - | - | -438.6 | - | -2,096.9 | |
| Table 5.3 | 0 | 0 | -326.0 | -438.0 | - | -2,095.0 |
| Method | Location | Girder | Slab, Haunch and Ext. Diaphragm | Parapets | FWS | Positive LL(3) |
Negative LL(4) |
|---|---|---|---|---|---|---|---|
| (ft.) | (k) | (k) | (k) | (k) | (k) | (k) | |
| Opis | 11 | 49.7 (1) | 52.8 (1) | 6.5 | 7.9 | 95.9 | -14.9 |
| QCon | - (5) | - (5) | - (5) | 8.8 | 99.4 | -13.0 | |
| Table 5.3 | 49.2 (2) | 52.2 (2) | 6.5 | 8.8 | 95.5 | -13.4 | |
| Opis | 55 | 0 (1) | -2.5 (1) | -3.0 | -3.6 | 36.2 | -60.5 |
| QCon | - | - | - | -4.0 | 36.7 | -61.7 | |
| Table 5.3 | -0.6 (2) | -3.1 (2) | -3.0 | -4.0 | 36.2 | -61.2 | |
| Opis | ≈ 110 | 0 | 0 | -14.9 | -17.9 | 0 | -130.9 |
| QCon | - | - | - | -19.9 | 0 | -132.1 | |
| Table 5.3 | 0 | 0 | -14.8 | -19.9 | 0 | -131.1 |
The following is sample Opis output for flexure at 55 ft. and 110 ft. from the end bearing. These results may be compared to the hand calculations in Design Step 5.6 for the positive and negative regions.
PERFORMING AASHTO LRFD SPECIFICATION CHECKS - 5.7.3.2 Flexural Resistance Point of Interest : 105.00 (55.0 ft.) Construction Stage: 2 Prestress Summary: dp = 74.502 in (from top) Aps = 6.732 in^2 fps = 264.532 ksi (avg. for all rows) POSITIVE Flexural Resistance: ** Analyzed as a RECTANGULAR Section ** Layer Area, in^2 Stress, ksi Force, kips Lever-Arm, in Moment i, in-k ----------------------------------------------------------------------------------- CS 507.832 -0.85*f'c -1726.627 3.095 5343.728 RT 2.000 -32.515 -65.029 2.132 138.670 RB 3.720 2.911 10.828 -0.180 1.950 PS11 0.612 264.145 161.657 -64.118 10365.045 PS10 0.918 264.309 242.636 -66.118 16042.478 PS 9 0.306 264.464 80.926 -68.118 5512.478 PS 8 0.306 264.464 80.926 -68.118 5512.478 PS 7 0.918 264.464 242.778 -68.118 16537.434 PS 6 0.306 264.610 80.971 -70.118 5677.476 PS 5 0.306 264.610 80.971 -70.118 5677.476 PS 4 1.224 264.610 323.883 -70.118 22709.904 PS 3 0.306 264.750 81.013 -72.118 5842.487 PS 2 0.306 264.750 81.013 -72.118 5842.487 PS 1 1.224 264.750 324.053 -72.118 23369.949 ----------------------------------------------------------------------------------- Sum -0.002 128574.031 Flexural Resistance Summary: beta 1 = 0.850 phi f = 1.000 c = 5.382 in Mn = 128574.031 in-k a = 4.575 in (from top) = 10714.503 ft-k f'c = 4.000 ksi (slab) phi*Mn = 128574.031 in-k
[AASHTO LRFD (5.7.3.2.1-1)] = 10714.503 ft-k (COMPARED TO 10,697 ft-k from hand calculations) Effective Shear Depth: [AASHTO LRFD 5.8.2.7] Tensile Force = 1791.655 kips dv = Mn / Tensile Force = 71.763 in Tensile Capacity of Reinforcement on Flexural Tension Side: [AASHTO 5.8.3.5] Rebar = 0.000 kips P/S = 1780.827 kips T(Cap) = 1780.827 kips Layer Codes: => C_ : C = Concrete, where _ may be: S = Slab, TF = Top Flange, W = Web, BF = Bottom Flange, ^T = Top fillets and tapers, ^B = Bottom fillets and tapers => R_ : R = Reinforcement, where _ is the row number (1-5, B (bottom), T (top)) => PS_ : PS = Prestress, where _ is the row number Notes: => The flexural resistance is determined based on: * Equilibrium * Strain compatibility * Strain in extreme compressive concrete fiber is 0.003 => The stress in the mild compression steel includes an adjustment for the displaced concrete. fs = (es * Es) + (0.85 f'c ABS(es / ey))
PERFORMING AASHTO LRFD SPECIFICATION CHECKS - 5.7.3.2 Flexural Resistance Point of Interest : 110.00 (110.0 ft.) Construction Stage: 2 NEGATIVE Flexural Resistance: ** Analyzed as a RECTANGULAR Section ** Layer Area, in^2 Stress, ksi Force, kips Lever-Arm, in Moment i, in-k ----------------------------------------------------------------------------------- RB 14.520 60.000 871.200 -67.445 58757.660 R1 1.550 -37.650 -58.358 3.590 209.478 CBF 159.381 -0.85*f'c -812.843 4.743 3855.703 ----------------------------------------------------------------------------------- Sum 0.000 62822.840 Flexural Resistance Summary: beta 1 = 0.750 phi f = 0.900 c = 7.590 in Mn = 62822.840 in-k a = 5.692 in (from bottom) = 5235.237 ft-k phi*Mn = 56540.555 in-k
[AASHTO LRFD (5.7.3.2.1-1)] = 4711.713 ft-k
(COMPARED TO 4,775 ft-k from hand calculations) f'c = 6.000 ksi (flange) f'c = 6.000 ksi (stem) Effective Shear Depth: [AASHTO LRFD 5.8.2.7] Tensile Force = 871.200 kips dv = Mn / Tensile Force = 72.111 in Tensile Capacity of Reinforcement on Flexural Tension Side: [AASHTO 5.8.3.5] Rebar = 871.200 kips T(Cap) = 871.200 kips Layer Codes: => C_ : C = Concrete, where _ may be: S = Slab, TF = Top Flange, W = Web, BF = Bottom Flange, ^T = Top fillets and tapers, ^B = Bottom fillets and tapers => R_ : R = Reinforcement, where _ is the row number (1-5, B (bottom), T (top)) => PS_ : PS = Prestress, where _ is the row number Notes: => The flexural resistance is determined based on: * Equilibrium * Strain compatibility * Strain in extreme compressive concrete fiber is 0.003 => The stress in the mild compression steel includes an adjustment for the displaced concrete. fs = (es * Es) + (0.85 f'c ABS(es / ey))
