Inspection of bridge girders in the fabrication plant is a requirement of Alberta Transportation and Economic Corridor’s (ATEC) Specifications for Bridge Construction, section 7, Precast Concrete Units.
According to this standard, fabricators are required to be certified by the Canadian Precast Concrete Quality Assurance, (CPCQA) certification program. This limits the production of bridge girders in Alberta to the following producers, at the time of this writing:
- Lafarge Precast (Edmonton)
- Eagle Builders (Red Deer)
- Knelsen Sand & Gravel (Calgary)
ATEC requires that plant inspectors of bridge girders require certification with the Precast Concrete Institute (PCI) plant inspection program.
Bridge girder inspection in the fabrication plant is performed with the aid of ATEC’s Engineering Consultant Guidelines for Highway and Bridge Projects manual, forms C-07 to C-09 for bridge girders and C-10 and C-11 for culverts. For standard bridge girders (SL, SLW, and SLC) the form serves as a checklist to the inspector. It includes all the important parts of bridge girder inspection, including:
- Material
Verification of reinforcing steel, prestressing strand, voids, and other material. Confirmation of design prestressing values. The prestressing calculations should have been provided to, and approved by, the consultant engineer prior to the production of the girders, and the inspector can determine the required elongation of the girders which is reduced to a simple elongation amount of each prestressing strand. The original strand length is marked with a marker and then the strand is pulled to the required elongation, allowing for a simple elongation measurement. Since multiple girders are normally produced in one, long concrete form, the elongation of the prestressing strands must correspond to all of the girders in that form. - Form set-up
In this section, the inspector confirms the prestressing elongation, gauge pressure, rebar, voids, dowels and lifting hooks and prior to concrete pouring operations. - Casting
During and after pouring the concrete, the inspector provides an approval to concrete casting operations and finishing. The inspector should, generally speaking, witness 100% of the concrete placement and finishing operation, to ensure that consolidation is sufficient. The slump, air content, and temperature of the concrete mix is recorded, and must be within the project specifications. The next morning (usually) a concrete cylinder is tested. If it is past the specified “release strength”, the girders are removed from the forms and must be moist cured. Once the girders are removed from the forms (usually the next morning), the girder finishing quality is recorded in this section of the form. - Removal from the Form
In this section of the form, the inspector records whether the stressing sequence was followed when prestressing cables were de-stressed, whether girders length, width, and camber are within tolerances, and the approval of any patching required. - Curing
This section allows the inspector to verify that each girder has been wet cured to the required 95% – 100% humidity for four days. - Finishes
The inspector records the girder sealer type and application rate, and girder finishing quality. - Final
The last category of the form is where the inspector records the quality of sandblasting, anchor bolts, and storage quality.
Roseke Engineering Ltd. provides a final report that includes the report forms for each girder as well as a summary of modifications requested from the fabricator, as well as pictures and overall summary. We recognize that unlike most concrete operations, the bridge girder fabrication process is one of the few areas where precision and attention to detail is paramount. In short, millimetres matter. We pride ourselves in ensuring a high quality girder fabrication process and our inspectors ensure that the final quality is without equal.
If you feel that bridge girder fabrication plant inspection services could be of use to you, please feel free to call Bernie Roseke, P.Eng., PMP, at (403) 942-6170. We look forward to hearing from you.
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