Page 32 - Bridge and Highway Structure Rehabilitation and Repair

CHAPTER 1 OVERVIEW OF BRIDGE ENGINEERING 7

What components of bridge to repair and rehabilitate?
Deck, deck joints, or bearings are subjected to deicing salts and constant wear and tear and
need the greatest attention. Usually the substructure is to some extent over designed and is less
likely to need repairs, except for repairs resulting from erosion or earthquakes.
Who is eligible to repair and rehabilitate?

An experienced or licensed professional engineer is qualified to oversee the delicate tasks.
Where to repair and rehabilitate on a priority basis?
Localized component repairs are needed. Selective criteria can be applied based on location

and on a priority basis. Bearings retrofit is one example.
Which bridges to repair and rehabilitate fi rst?
Those which require emergency work have a higher priority. Condition evaluation of each
item is based on the list provided by the recording and coding guide. Interstate bridges, those
on military routes, or those serving schools, fire stations, and hospitals should have top priority.

Evaluation of defects should be confirmed by in-depth inspection or nondestructive testing.
How to initiate repair and rehabilitation?
1. The first step is field inspection and structural health monitoring.

2. The second step is preparing an inspection report.

3. The third step is computing the condition rating and sufficiency rating, for funding
approval.
4. The fourth step is analysis and load rating (both inventory and operating ratings). Additional
ratings for extreme loads such as scour and seismic vulnerability may be required.
5. The fifth step is preparing a rehabilitation report.

6. The sixth step is implementing diagnostic design procedures.

7. The seventh step is selecting methods of repair, retrofit, rehabilitation, or replacement.
8. The eighth step is preparing contract documents and selective reconstruction.

Is there a choice between rehabilitation and replacement?

With thousands of bridges to be fixed, economics, inconvenience to the public during recon-
struction, or sentimental/historical reasons can discourage replacement. Replacement is expensive
and causes interruption in service during the construction period. Environmental concerns and
permit requirements will be greater for new bridges, especially those with four or more lanes.

A sufficiency rating, diagnosis of deficiencies, and cost benefit analysis need to be performed
to determine the course of action.
Planning and design procedures for replacement are covered by LRFD Design Specifi cations

and will only be briefly discussed in this book.
1.3 THE NEED TO KEEP BRIDGES FUNCTIONAL
1.3.1 Maintenance Engineering
A bridge needs to be reconstructed after each complete maintenance cycle (Figure 1.2).
General considerations include a variety of interdisciplinary approaches, including:
1. Extensive planning considerations, such as
• Funding and cost
• Functional requirements
• Right of way
• Maintenance and protection of traffic and staged construction

• Relocation of utilities