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Section 6: Trimming or Cutting Prestressed Concrete Girder Ends

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Description

This section includes allowances and repair procedures for trimming or cutting the ends of prestressed concrete I-beams.

Cutting beam ends requires preparation of an NCR from the Fabricator. The TxDOT Inspector determines whether an NCR is required when a beam end will be trimmed.

NOTE: Standard provisions for cutting beam ends apply to Tx Girders (bulb tees) only. Cutting the ends of prestressed members other than Tx Girders requires a detailed analysis by a Professional Engineer and authorization from TxDOT CST Headquarters or the Bridge Division. There is no standard repair for such alterations; proposals will be considered on a case-by-case basis.

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Provisions for Acceptance

No more than 12 inches may be removed from either girder end.

If more than 6 inches is removed from a girder end, include in the modification proposal stamped calculations from a Professional Engineer indicating the viability of the proposed modification. Calculations must include:

In most cases equal amounts should be removed from each end if the total length to be cut exceeds 6 inches. However, that would not be a viable solution if a beam end is being cut in order to eliminate damage or when a beam end contains an anchor slot.

The Area Engineer and CST Engineer must approve modifications. All parties, including the Fabricator, Contractor, and Engineer, must agree that trimming will not result in any unacceptable issues related to deck forming, slab or haunch thickness, camber, or plan profile deck geometry.

The girder must be modified as required for use in its new configuration, including but not limited to blockouts, inserts, hangers, and bevels.

When the strand pattern differs from the destination design, or if more than 6" is cut off one or both beam ends, a replacement shop plan for the permanent record must be provided that indicates all characteristics of the candidate girder that differ from the originally specified girder.

Include dual girder identification by permanently marking the inside face of the girder, clearly indicating which is the previous girder I.D. and which is the current I.D. Fabricator or Contractor must send written notification to the Area Engineer informing them of the circumstances of the dual marked girder for their information and records.

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Repair Procedure

After the beam has been trimmed or cut, re-measure the member (length, skew, and batter) to ensure that the altered dimensions are acceptable.

Once the dimensions have been checked and found to be acceptable, remove all vertical reinforcement that has less than 3/4-inch concrete cover. Recess longitudinal reinforcing steel and prestressing strands approximately 3/8-inch.

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  • Locate the steel using shop drawings, exploratory drilling, and whatever other means is necessary to ensure that all reinforcement with inadequate concrete cover is identified.
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  • Remove the steel using a torch or other approved method. Do not overheat or damage the surrounding concrete and steel that will remain in place.
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  • If steel is removed using a torch, abrade the steel and concrete surfaces with a needle gun, steel brush, or other suitable means to ensure that no slag remains.

Apply a silane penetrating sealer and neat Type VIII epoxy to every portion of the member that was trimmed or cut. Wait at least 48 hours after applying the penetrating sealer before applying neat epoxy. Do not extend the neat epoxy material with sand except to fill in the voids where the steel has been recessed or removed.

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