These bolts are connected in steel to the foundation to provide sustainability and resist various forces such as wind, seismic activity like earthquakes, and structural loads.
Despite their importance, anchor bolt installations have some common errors and are often costly.
In this post, we will explore some common installation mistakes, their consequences, and practical tips to avoid them.
The Importance of Anchor Bolts in PEBs
Anchor bolts in pre-engineered buildings cannot be stressed enough; precision and accuracy of the anchor bolt, as PEBs are pre-manufactured at a different location and then shipped to a site, in other words, the building is prefabricated.
Any misalignment or discrepancy in the actual placement of where the anchor bolts are installed compared to the intended engineered layout can lead to delays, require modifications, or, in a worst-case scenario, affect the safety of the entire structure.
Installation Errors for Common Anchor Bolts
1. Incorrect Location or Installation.
Problem: The anchor bolts are installed out of position, out of grid, or not spaced correctly.
Consequences: Steel columns will not fit; reworking is needed (sometimes multiple instances of reworking of anchor bolts involve drilling, welding, or modifying the base plate).
2. Incorrect Bolt Projection Height.
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Problem: The bolts are set too high or too low above the level of the foundation.
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Consequences: Difficulty installing base plates, which will include poorly attached members or shimming.
3. Improper Orientation.
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Problem: The bolts are situated or facing in a rotated plane or are not parallel with the direction of the steel members.
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Consequences: Bolt holes on base plates may not align and need to be reworked on-site.
4. Incorrect Type or Size of Bolt.
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Problem: The bolts used do not meet the design or specifications.
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Consequences: It may compromise structural integrity and result in expensive replacement costs.
5. Embedment Depth Isn't Deep Enough.
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Problem: Bolts are too shallow in the source concrete.
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Consequences: Load-carrying capacity will be diminished and over-stretched during tension, which could cause the bolts to pull out of the concrete in the most severe cases
6. No Template for Casting
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Problem: There were bolts installed when there was no holding template.
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Consequences: Random chances for alignment (or projection) errors.
How to Prevent Anchor Bolt Installation Mistakes
✅ Utilize Approved Anchor Bolt Drawings
The site team must only use the final and approved or discussed anchor bolt layouts from the PEB supplier. Do not use preliminary drawings.
✅ Fabricate and Employ a Steel Template
A steel setting template provides for precise placement, orientation, and projection of anchor bolts. It is one of the simplest ways to mitigate error.
✅ Conduct Pre-Installation Verification
Before installation begins, check and double-check foundation levels and centerline marks.
✅ Supervisor and Quality Control
Appoint a qualified supervisor or engineer to manage the site installation of the anchor bolts, especially when it comes time to pour the concrete.
✅ Surveying and Verification of Layout
Use surveying equipment, i.e., total stations, to verify the X, Y, and Z coordinates of the positions of the bolts.
✅ Protection for Curing
After placement, before curing, protect anchor bolts from movement with support or jigs.
While the importance of anchor bolt error may seem minor, its consequences to pre-engineered buildings can be serious.
Delays, changes to the structure, and cost overruns can all occur. Good execution ultimately always comes down to good planning, good work, and supervision.
By concentrating on the accuracy of measurements and following best practices, contractors and site engineers can be confident that this crucial interaction between foundation and structure will work exactly as it was designed and intended.
For more: https://ecopeb.com/
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