Connection Design RFIs – Misaligned anchors and notches in base plates

This article is the first part of a series "Connection Design RFIs."
Read all articles in the series.

 Minor misalignments = big pain

In construction projects, misaligned anchor bolts and notches in base plates are common issues faced by engineers and contractors. While minor misalignments can be addressed through adjustments on-site, larger deviations will need more complex solutions. These unconventional solutions, often requiring detailed recalculations and EOR approval, can lead to project delays ranging from a few hours to a couple of days, depending on the complexity of the issue and the speed of approval. 

The picture below represents the issues in the field. The Disalvo Engineering Group shared this example, in which they wanted to represent the notch on the base plate using IDEA StatiCa, as they needed to approve the on-site changes.  

AISC Design Guide 1 offers traditional solutions for addressing misalignments, such as shimming, notching, or enlarging holes. However, each of these methods carries specific limitations. One significant challenge is the need to recalculate connection strength to ensure that any modifications maintain structural integrity. These field changes can transform simple designs into complex issues that require advanced analysis, complicating the approval process and potentially leading to costly delays.

How IDEA StatiCa makes it easier

IDEA StatiCa helps engineers to visualize how different modifications, such as repositioning anchor rods or adjusting base plates, impact the overall connection performance in real time. The ability to quickly model and simulate multiple design scenarios can cut down the time for testing potential fixes from several hours or days to just a few minutes.

• Instant Visualization: Engineers can easily input the misaligned anchor rod positions into the software and visualize potential solutions, such as slotting the base plate or repositioning anchor rods.
• Code Compliance: IDEA StatiCa automatically checks whether the modified connection complies with design codes, such as AISC and ACI, ensuring that the solution will be safe and effective without the need for manual recalculations.
• Efficiency in Design Adjustments: For post-installed anchors or misaligned base plates, IDEA StatiCa allows quick adjustments, modeling the exact layout to reflect the actual conditions on-site. This minimizes guesswork and trial-and-error fixes.
• Real-time Feedback: Rather than waiting for approval from multiple parties after each adjustment, IDEA StatiCa provides real-time analysis, allowing engineers to optimize the solution and move forward confidently.
• Significant Time Savings: By removing the analytical approach, IDEA StatiCa enables users to model changes quickly and efficiently, allowing them to assess whether connections are safe without the delays associated with conventional methods.

Summary

While AISC offers reliable solutions for base plate and anchor bolt misalignments, using IDEA StatiCa significantly reduces project delays caused by field adjustments through efficient analysis and design verification. Engineers can provide immediate solutions for misaligned bolts or base plates, allowing contractors to resume work quickly, which reduces idle time on-site and saves both time and money.