Page 285 - Bridge and Highway Structure Rehabilitation and Repair

260 SECTION 2 STRENGTHENING AND REPAIR WORK

For non-composite and non-compact sections, service II limit state does not need to be
checked.
Maximum positive moment evaluation method is applicable to both single span and con-
tinuous beams. However, the maximum negative moment evaluation method is only applicable
to continuous beams. Maximum positive moments in equal span continuous bridges can be
calculated using a similar approach as used for single spans.
Footprints of continuous span bridges show that they are likely to be of unequal span lengths.
Hence, a simplified analysis approach giving a summary of results cannot be formulated. Instead,

the influence line method or continuous beam analysis results using conventional three moments
theorem are presented and compared to those from computer programs.
Maximum bending moments:
1. Positive moment at midspan for a variety of loads (non-symmetric axle 4 lane).

2. Positive moment at midspan for alternate tandem axle loads (symmetric axle 4 lane).
3. Negative moment at supports for non-symmetric axle loads 4 lane loads.

6.5.7 Shear Design
Strength I limit state:
SF at girder ends: Compute V DC4DW
Compute V
LL4IM
Girder web D , t :
w
W
Required end panel transverse stiffener spacing for stiffened girders 1.5 D.
Shear resistance of end panel:
Maximum shear forces:
Maximum shear force at supports for variety of loads (non-symmetric axle 4 lane)

Results of a simplified analysis approach can be presented in a summary of tables. The
comparative study would help in frequently used design and rating for moments and forces.

6.6 RATING OF SECONDARY STRUCTURAL MEMBERS

6.6.1 Summary of Rating Procedure for Transverse and Bearing Stiffeners
(Provided for ready reference)
1. Strength Limit States I and II
2. Refer to (6.10.8) Stiffeners
3. Refer to (6.10.8.2.1) for Bearing Stiffener Location
4. Refer to (6.10.8.2) for Axial Resistance and Bearing Stiffener Geometry

6.6.2 Shear Connectors
(Provided for ready reference)
1. Strength Limit States I and II
2. Refer to Sec. 6.10.7.4 for shear connectors.
The following steps are provided for ready reference. Prior to developing a software or for
solving the equations using hand calculations, equations need to be checked against the latest

version of applicable AASHTO LRFD Specifications or LRFR Manual.