Flexible Post Assembly Reducing Anchor Pullout Forces
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Solution Overview
Problem
Traditional guardrail systems with rigid posts face limitations in load capacity due to the pullout resistance of anchor bolts, requiring large base plates that are costly and can compromise the structural integrity of concrete slabs, especially in car park environments.
Innovation Solution
A post assembly design featuring a common base plate with a footing and lever arm separated by an elongate slot, allowing the lever arm and post to pivot away from the impact side, reducing pullout forces on fasteners and distributing impact energy through plastic deformation, while maintaining the rail element's height to effectively contain vehicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid post systems use large base plates to increase load carrying capacity, then the pullout resistance of anchor bolts is improved, but the material cost increases and the structural integrity of the underlying concrete slab is compromised
Solution Approach 1:
The invention changes the fundamental parameter of post rigidity from rigid to flexible. The flexible post can deflect and rotate under impact load, transferring less pullout force to the anchor bolts. This allows the use of smaller base plates with fewer bolts while maintaining adequate load carrying capacity, thereby reducing material costs and minimizing damage to the concrete slab.
Solution Approach 2:
The invention introduces dynamic behavior to the post system through flexibility. Instead of a static rigid post that transfers full impact force to the foundation, the flexible post dynamically deflects and rotates, absorbing impact energy and reducing the peak pullout forces on anchor bolts, enabling smaller base plates.
2Strength
If rigid post systems use multiple anchor bolts to resist impacting vehicle, then the load carrying capacity is sufficient, but the holes drilled compromise the structural integrity of the concrete slab
Solution Approach 1:
By changing the post from rigid to flexible, the load transfer mechanism changes. The flexible post reduces peak pullout forces on anchor bolts through deflection and rotation, allowing the use of fewer bolts. This reduces the number of holes drilled in the concrete slab, thereby preserving its structural integrity while maintaining sufficient load carrying capacity.
3Force
If rigid post systems use large footprint base plates to position anchor bolts far from post base, then the pullout force on anchor bolts is reduced, but the base plate size becomes difficult to accommodate in car park environment
Solution Approach 1:
The invention changes the post flexibility parameter to reduce pullout forces on anchor bolts. This allows the use of smaller base plates with bolts positioned closer to the post base, as the flexible post compensates for the reduced bolt distance by absorbing impact energy through deflection and rotation, eliminating the need for large footprint base plates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances energy absorption and reduces peak pullout forces on anchor bolts, allowing for fewer bolts to be used, minimizing material costs and structural damage, while maintaining the rail element's height to improve containment efficiency during impacts.
Implementation Method 1
the hinge region plastically deforms and the lever arm and post deflect about the footing, away from the impact side of the plate
Data Source
AI summary
A post assembly for absorbing impact from a vehicle including a footing, an upright post and a hinge region to allow the post to plastically deform relative to the footing. The post is preferably fixed to a lever arm that is connected to the footing via the hinge region, the lever arm and post pivoting away from the footing under load, The lever arm, footing and hinge region are preferably formed from a common base plate. The invention also relates to barrier system that includes multiple post assemblies, and a barrier supported between respective posts of the assemblies.