Bollard Stress Control Device for Impact Load Distribution
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Solution Overview
Problem
Current bollard installations provide inadequate structural protection against low-speed vehicle impacts, as they often result in excessive bearing stress between the bollard post and surrounding pavement, leading to bollard penetration and vehicle launch, due to insufficient foundation design and lack of guidance in building codes.
Innovation Solution
A bollard assembly incorporating a stress control device with a face plate and radially extending support plates, which increases the contact area between the bollard post and pavement, reducing localized stresses and allowing for a shallower foundation by distributing impact forces more effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional bollard post is installed in a concrete foundation pier, then the bollard provides basic vehicle barrier function, but the bearing stress between the bollard post and surrounding pavement becomes excessive during impact, leading to bollard penetration and vehicle launch
Solution Approach 1:
The stress control device segments the load transfer path by introducing multiple support plates spaced vertically along the bollard post. These plates divide the impact force into multiple contact points with the foundation pier, preventing excessive stress concentration at any single location and eliminating the need for overly deep foundations.
Solution Approach 2:
The stress control device creates a composite structural system combining the bollard post, multiple support plates, and foundation pier. This composite structure distributes impact forces through the vertical arrangement of support plates, enhancing overall load-bearing capacity and preventing bollard penetration while reducing bearing stress on the pavement.
2Stress or pressure
If the foundation pier depth is increased to reduce bearing stress, then the bollard assembly requires more excavation and uses more material below grade, but this increases construction complexity and cost
Solution Approach 1:
By segmenting the load transfer through vertically spaced support plates, the foundation pier can be shallower while still distributing forces effectively. Each support plate acts as an independent load transfer point, allowing the foundation to engage deeper soil layers progressively rather than requiring a single deep embedment.
Solution Approach 2:
The invention changes the stress distribution parameters by introducing multiple support plates at specific vertical intervals. This transforms the stress distribution from a concentrated bearing stress at the base to a distributed pattern along the foundation pier length, optimizing both stress reduction and foundation depth.
3Strength
If the bollard post contact area with pavement is increased to reduce localized stresses, then the moment capacity of the bollard assembly is enhanced, but this requires additional structural components and installation complexity
Solution Approach 1:
The moment capacity is enhanced by segmenting the lateral support function across multiple support plates spaced vertically. Each plate provides lateral bracing at its elevation, creating a distributed support system that resists bending moments more effectively than a single base connection, while keeping each individual plate relatively simple in design.
Solution Approach 2:
The invention adds the vertical dimension to the support system by spacing support plates at different elevations along the bollard post. This three-dimensional arrangement of support plates creates a more effective moment resistance mechanism compared to traditional two-dimensional base-only support, distributing lateral loads throughout the assembly's height.
Data Source
AI summary
A bollard assembly includes a bollard post, a ground sleeve configured to receive the bollard post, and a stress control device positioned adjacent to the ground sleeve. The stress control device has a face plate and a plurality of support plates secured to a back surface of the face plate. The support plates are angularly space from one another at equal angles and extend radially inward from the back surface towards the ground sleeve such that the ground sleeve fits between the plurality of support plates.