Page 282 - Bridge and Highway Structure Rehabilitation and Repair

CHAPTER 6 APPLICATIONS OF BRIDGE DESIGN AND RATING METHODS 257

Non-composite section (positive and negative fl exure):
1. Applicable to I section.
2. Strength limit states I and II.
3. Construction limit state and uncured slab.
4. Refer to Section 6.10.5.2.3.
Non-composite non-compact section (positive and negative fl exure):

1. Strength limit states I and II.
2. Construction limit state and uncured slab.
3. Refer to Sections 6.10.5.3.2 and 6.10.5.3.3.

6.5.3 Unfactored Dead and Live Load Moments with Impact
Multi-girder bridge span of 80 ft: Four steel plate girders @ 250 lbs/ft wt., spaced at 10.33
ft centers, slab thickness of 7 in and 3 in haunch, superimposed dl 3 2.0 kips/ft,
4
DL moment of inertia, I 3 24,416 in , y 3 19 in
b
4
SDl moment of inertia, I 3 46,613 in , y 3 29.7 in
b
4
I 3 67,576 in , y 3 39.79 in
b
DL on interior girder:
1. Slab 0.15k/cft 8 10.33 ft 8 0.58 ft 3 0.9 k/ft
2. Haunch 0.15 8 1.33 ft 8 0.25 ft 3 0.05 k/ft
3. Girder 0.25 k/ft 4 0.03 k/ft (for stiff. and diaphragm) 3 0.28 k/ft
Total DL 3 1.23 k/ft
2
Mdl 3 1.23 8 (80) /8 3 984 k-ft
2
Msdl 3 (2.0/4) 8 (80) /8 3 418 k-ft
Live load of HS-20 acting on single 80 ft span, Ml 3 582.4 kip-ft, impact factor 3 0.244
M (L 4 I) 3 1.244 8 582.4 8 1.88 3 1362 kip-ft

6.5.4 Buckling Capacity Rating of Steel Girders for Load Combinations
(Summary of steps refer to LRFD sections)
Non-compact section compression fl ange buckling:
1. Strength limit states I and II.
2. Construction limit state and uncured slab.
3. Refer to Section 6.10.5.3.3c and LRFD Eq. 6.10.5.3.3c

Non-composite non-compact section lateral torsional buckling:
1. Positive and negative fl exure.
2. Strength limit states I and II.
3. Construction limit state and uncured slab.
4. Refer to Sections 6.10.5.5 and 6.10.6.4.
5. L 1.76 r (E/F ) 1/2
b 1 yc