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RECOMMENDATIONS FOR INSPECTION AND
MAINTENANCE OF EXCEL STEEL BRIDGES
INSPECTION
| I. |
USER SAFETY (INSPECTION BY OTHERS)
| A. |
Each bridge should be inspected at regular intervals (at least once per year) to ensure that all items of user safety are accounted for and performing properly. Those areas of special concern should be as follows:
| 1. |
All safety rails, handrails, rubrails, fencing or other types of safety features should be in place with complete structural integrity and capacity. There shall be no sharp edges or protrusions on any feature that could produce bodily harm or be a hazard to the user.
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| 2. |
All deck surfaces should be without gaps, cracks or projections that could create a trip hazard or interfere with the user in any way. Special consideration should be given to any smooth deck surface that could also create a possible slip hazard.
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| II. |
STRUCTURAL INTEGRITY (INSPECTION BY OTHERS)
| A. |
Each bridge should be inspected at regular intervals not to exceed one year. Pages 5-13 of the American Association of State Highway and Transportation Officials (AASHTO) Manual for Maintenance Inspection of Bridges provides an excellent guide for this inspection. We recommend its use, particularly in the case of bridges for vehicular use. This visual inspection should include, but not be limited to the following:
| 1. |
Check the decking to insure it is in satisfactory condition. Pay special attention to timber decks at their contact surfaces where they bear on stringers.
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| 2. |
All steel surfaces should be inspected to insure that they are performing satisfactorily. Check for any excessive corrosion on weathering steel bridges or paint and caulk integrity on painted bridges, paying special attention to the following areas:
| a. |
All steel below the deck, particularly the tops of stringers supporting wood decks.
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| b. |
Truss or floor system joints where debris or water may accumulate.
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| c. |
Anywhere vegetation or other material may have come in contact with the steel.
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NOTE: Any weathering steel surface not "boldly exposed" to the atmosphere should be checked to insure it has formed its protected oxide layer.
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| 3. |
Check all steel surfaces and welded and bolted connections for cracks. Pay special attention to the welded truss and floor beam joints in vehicular or material handling bridges subject to fatigue stresses.
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| 4. |
Check the ends of the bridge for any damage which may have been caused by vehicular impact.
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| 5. |
Check the integrity of concrete abutments and/or piers for scour due to water flow if applicable, etc., per AASHTO's Manual for Maintenance Inspection or the foundation engineer's recommendations.
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| 6. |
Check anchor bolts for damage and see that they are secure. Examine all bearings to ascertain that they are functioning properly. Expansion bearings and the expansion joints at the ends of the bridge must be checked to see that they can move freely and are clear of all foreign material.
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| 7. |
SPLICED BRIDGES:
| a. |
Check the bolted splices for any excessive corrosion or cracking of the steel or fasteners,
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| b. |
Make sure all weep holes are open and clear of debris to allow for complete drainage of any moisture which may collect on the interior tube surfaces.
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| B. |
If problems are seen during the inspection procedure, cleaning and repair or replacement of weathering steel bridge components may be necessary; painted bridges may require cleaning and repainting or replacement of some or all members.
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MAINTENANCE FOR PAINTED BRIDGES
Painted bridges, like any painted structure, require periodic inspections and painting. The following steps will help increase the life span of your bridge:
| A. |
After inspections, or any time loss or damage of the paint coat is noticeable, problem areas should be repaired as follows:
| 1. |
Select a maintenance coating system based on the following:
| a. |
Inspection report findings
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| b. |
Environment (identify any corrosives)
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| c. |
Degree of surface preparation attainable
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| d. |
Current paint compatibility
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NOTES:
| * |
Generic type compatibility is a major factor in the selection of a system (some coating systems are not recommended over a particular type of existing material).
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| * |
Depending upon the surface performance, an upgrade in the coating system may be necessary at this time.
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| 2. |
Clean all applicable surfaces as dictated by the repair system chosen (i.e., pressure wash, brush off, blast clean, etc.)
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| 3. |
Apply repair coats per the coating manufacturer's recommendations.
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| 4. |
Caulk all unwelded seams which are in need of repair with a good quality clear silicone caulk suitable for exterior use.
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| B. |
The entire bridge structure will require periodic repainting dependent upon varying factors such as the existing paint system, bridge usage, atmospheric environment, etc. Repainting will typically be required every 2-10 years. The frequency of painting will need to be determined by the inspector. The following steps should be followed when repainting the bridge structures:
| 1. |
Remove wood decking or grating, fencing, wood rubrails and any other non-painted items which will not be receiving new paint. Obviously, concrete and asphalt decked bridges will be painted with the deck in place, unless these decks have deteriorated to the point of replacement. If this is the case, remove the deck prior to painting, if not, special care should be exercised to insure problem areas below deck are cleaned and painted properly.
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| 2. |
Select a coating system based on parameters similar to those outlined in the repair painting section, paying attention to the following items:
Environment, specifically any corrosives identified during inspections
Substrate condition
Surface preparation limitations
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| 3. |
After selecting a system compatible with all existing surface conditions and site limitations, clean all surfaces and apply according to the manufacturer's recommendations.
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| 4. |
After the coating system has properly cured, caulk all unwelded seams with a good quality clear silicon caulk suitable for exterior use and replace the decking, fencing, etc., which were removed prior to cleaning and repainting the structure. This is also an excellent time to replace the wood rubrail which may have shown excessive deterioration.
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MAINTENANCE FOR WEATHERING BRIDGES
Weathering steel is not a maintenance free material. The following steps will help increase the life span of your bridge. Excel recommends rinsing the steel truss and beneath the bridge every 3 months if the bridge is within a five-mile radius of the ocean.
| A. |
Do not use de-icing salts for snow removal. De-icing salts can severely damage the weathering steel.
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| B. |
Avoid retention of debris on the steel surfaces. Flush bridges at areas which accumulate debris (including salt) on a regular basis.
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| C. |
Prevent weathering steel from contact with vegetation, masonry or other materials so that the weathering process can proceed on a natural basis.
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| D. |
If excessive corrosion is encountered due to salts from adjacent roadways or roadways beneath an overpass structure, or for any other reason, it may be wise to blast clean and paint the truss joints, the steel beneath the deck or any area which exhibits excessive corrosion.
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MAINTENANCE FOR DECKING
| I. |
WOOD DECKS
Wood is a natural material which exhibits large volume changes with variations in moisture content and time, particularly in the width direction, which can cause gaps to form between the planks. Cupping and splits may also occur which need to be repaired.
Please note: It is the owner's responsibility to keep the wood deck free from cupping, splits, gaps and smooth surfaces.
| A. |
Replace all planks that have deteriorated past a useful and safe life.
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| B. |
Eliminate gaps between the planks which might be large enough for a high-heeled shoe to become lodged. Eliminating the gaps should be done as follows:
| 1. |
Remove all deck bolts.
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| 2. |
Remove plank hold-down angles. Be sure to mark their locations for ease of reinstallation.
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| 3. |
Slide wood planks together.
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| 4. |
Add new plank or planks to fill up the excess space.
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| 5. |
Reinstall plank hold down angles.
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| 6. |
Drill new holes in wood planks.
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| 7. |
Install new deck bolts (see shop drawings for size and material).
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| C. |
Replacement planks may be purchased through Excel.
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| D. |
Over time with exposure to the environment, wood may become smooth, particularly when wet with rain, dew, snow, sleet, ice, etc. Periodically it may be necessary to "roughen" the surface of the decking with large grit sandpaper.
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| II. |
GRATING DECKS
| A. |
Repair or replace any grating which shows damage or deterioration to the main bearing bars.
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| B. |
If galvanized, inspect to see if corrosion has occurred. Wire brush any spots exhibiting corrosion and repair. We recommend the use of either sprayed zinc metalizing or the use of organic zinc rich paint for repairing galvanized surfaces.
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| C. |
For weathering steel grating, if excessive corrosion is encountered due to salts from adjacent roadways or roadways beneath an overpass structure, or for any other reason, it may be wise to blast clean and paint the grating.
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| III. |
CONCRETE & ASPHALT
For all concrete and asphalt decks, Excel Bridge supplies a steel corrugated form decking to aid in the placement of the concrete or asphalt. For asphalt decks, this steel form is the main load carry member. For concrete decks, this steel form may or may not be integral to the deck design (as in a composite deck). The contractor places the reinforcing and concrete, or the asphalt, after installation of the bridge.
During inspection, the asphalt or concrete covering should be checked for excessive cracking and deterioration. At the same time, the seal form decks should be checked for excessive rusting and/or damage. If the coverings are deemed to require replacement, the steel forms may be reused if they are not damaged or do not show excessive corrosion.
Structural form decks (for asphalt decks and composite concrete decks) may require replacement even when the deck surface itself is sound.
Excel concrete and asphalt decks are usually not designed to accept the added dead weight of an overlay. Therefore, the only remedy is repair of the cracking or replacement of the concrete or asphalt covering.
See the shop drawing for recommended concrete strength, reinforcing size, slab and asphalt thickness, control joint location and surface finish.
Please note: Maintenance of the bridge decking, including keeping it free from slip or trip hazards, is the owner's responsibility.
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