Case Study: Comparing Perma-Columns and Competitor Columns for Post-Frame Construction
INTRODUCTION
Post-frame construction relies on strong, stable foundations to ensure long-term structural integrity. This case study compares the performance of the Perma-Column foundation system with a competitor foundation system under simulated load conditions, specifically horizontal and vertical forces, to determine their suitability for application in post-frame buildings.
Testing Overview
The evaluation involved three tests designed to measure the foundation’s strength and stability:
- Top Pull Test, which applied a horizontal load at the top of the posts.
- Base Pull Test, which applied a horizontal load near the base of the posts.
- Uplift Test, which applied a vertical load pulling upward on the posts.
These tests measured translation, and rotational failure points under increasing loads.
Performance Comparison
1. Top Pull Test (Horizontal Load at the Top of Posts – Applied Bending at the Base)
Competitor Foundation System
The competitor foundation system demonstrated limited resistance to horizontal loads during the top pull test. The 4-ply 5′ competitor foundation system failed at 200 lbs due to weld failure between the post’s saddle and column. Similarly, the 4-ply 7′ competitor foundation system experienced weld failure at low loads, with significant deflection noted at the same loads as the 5’ column. These results highlight the susceptibility of the competitor foundation system to early failure under moderate horizontal forces that cause bending at the base of the post.
Perma-Columns
Perma-Columns outperformed the competitor foundation system in horizontal load resistance. The 7′ 8400 Perma-Column withstood loads up to 500 lbs before experiencing wood shear failure at the bolts, transitioning to a pinned connection. The 7′ 8500 Perma-Column resisted even higher loads, with failure occurring at 670 lbs due to saddle bending. These results indicate that Perma-Columns can handle greater horizontal forces that introduce bending at the base before reaching structural failure.
2. Base Pull Test (Horizontal Load at the Base of Posts)
Competitor Foundation System
The 3-ply 5′ Competitor’s Foundation System exhibited moderate resistance to horizontal loads near the base. Displacement steadily increased with load, and the foundation system failed at 890 lbs when translational deflection exceeded 9/16″. This indicates that Competitor’s Foundation System offers some stability but are less effective in resisting base-level horizontal forces compared to Perma-Columns. Also, when considering cyclical loads, it’s possible that the competitor foundation system would significantly underperform when compared to the Perma-Column, possibly leading to excessive racking.
Perma-Columns
The 8300 Perma-Column demonstrated excellent performance during the base pull test. It sustained up to 1500 lbs before translational deflection exceeded 1/2″. This significantly higher threshold highlights the superior base stability of Perma-Columns, making them more reliable in conditions requiring strong lateral resistance or reduced lateral deflection.
3. Uplift Test (Vertical Load Resistance)
Competitor Column
The competitor foundation system showed mixed results in resisting vertical forces. The 4-ply 5′ Competitor Column reached a final deflection of 1-5/16″ under a 5000-lb load.
Perma-Columns
Perma-Columns outfitted with the uplift anchor system performed better in the uplift test. Under the same 5000-lb load, the Perma-Column exhibited a final deflection of 1-1/16″. But the difference in performance is not significant.
Analysis and Recommendations
Key Findings
The testing revealed that Perma-Columns consistently outperformed the Competitor’s Foundation System across all measured criteria:
- In horizontal load tests, Perma-Columns displayed greater resistance to both top-level and base-level forces. Competitor’s Foundation System, by contrast, experienced early failures, particularly at weld points.
- The competitor’s Foundation System showed higher deflection and residual deformation, indicating less structural stability and durability over time.
- Both foundation systems performed similarly when a vertical load was applied.
Recommended Applications
Based on the test results, Perma-Columns are the preferred choice for most post-frame construction projects. Their robust resistance to horizontal and axial uplift, combined with their durability under stress, makes them ideal for:
- Post-Frame buildings that are exposed to significant lateral forces, such as high winds or seismic activity.
- Projects requiring long-term structural reliability, such as agricultural, commercial, or industrial post-frame structures.
While the Competitor’s Foundation System may still have a place in projects with lighter load requirements, its susceptibility to early weld failure and permanent deformation limits its suitability for demanding applications. To improve their competitiveness, enhancements in weld strength and material quality would be necessary.
Conclusion
In post-frame construction, where foundational performance is vital, Perma-Columns clearly outperform the Competitor’s Foundation System in strength, stability, and durability. Their ability to resist higher loads and minimize deformation ensures enhanced safety and longevity, making them the superior choice for most post-frame building projects.
