Page 281 - Bridge and Highway Structure Rehabilitation and Repair

256 SECTION 2 STRENGTHENING AND REPAIR WORK

• Infinite life fatigue check.

• Calculate remaining fatigue life.
• Legal load rating.
• Permit load rating.

6.5.2 Flexural Capacity Rating of Steel Girders for Load Combinations
(Summary of steps refers to LRFD sections)
In Chapter 5, steps for AASHTO design method was summarized.
Member proportions (I /I ) web slenderness (6.10.2.2):
yc y
For plate girder webs, D/t 150
w
For compression flange composite with deck slab, b 9 D/5

c
t 9 1.2 b c
c
b /2 t 12
c c
For tension fl ange, b 9 D/4
t
b 9 1.2 b c
t
b /2 t 12
t t
1. Strength limit states I and II (6.5.4.1).
2. Service II limit state (6.10.4.1) and (6.10.4.3).
3. Fatigue limit state ((6.10.5).
4. Deflection limit state (6.10.3.2) and (6.10.4.2).

5. Refer to Section 6.10.1.1 (preliminary section calculations).
6. 0.1 (I /I ) 0.9.
yc y
Flexural resistance M (6.10.8):
n
1. Strength limit states I and II (6.5.4.1).
2. Construction limit state.
3. Refer to Section 6.10.5.6.
Composite compact section:

1. Strength limit states I and II.
2. Service II limit state (C 6.10.4_1).
3. For 70W steel and construction limit state assume non-compact.
4. Redistribution of moments in continuous girders permitted.
5. Refer to Section 6.10.5.2.2c, 6.10.5.2.3, and 6.10.2.2.
6. Refer to Section 6.10.5 for I girder.
7. Section A6.2 for yield moment.
Composite non-compact section:

1. Strength limit states I to V.
2. Service II limit state.
3. Construction limit state.
4. Refer to Sections 6.10.5.3.2 and 6.10.5.3.3.
5. Refer to Section 6.10.5.3.2b for non-compact web slenderness.