Tensionless Concrete Pier Reinforcement for Overturning Capacity
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Solution Overview
Problem
Existing tensionless concrete pier foundations face challenges in increasing overturning moment capacity and reducing movement and deflection, particularly when supporting tall and heavy structures, as they are prone to fatigue and premature failure under alternating loads.
Innovation Solution
The introduction of reinforcement structures such as post-tensioned collars, extended base flange supports, soil condition improvement collars, buttress additions, and pressure grouting to enhance the lateral stiffness, shear resistance, and load-bearing capacity of tensionless concrete pier foundations, which include embedded shear steel, radially-extending horizontal bolts, and additional anchor systems to distribute loads and improve soil integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcement structures are added to increase overturning moment capacity, then the structural strength is improved, but the device complexity increases
Solution Approach 1:
The reinforcement collar is nested within the existing tensionless pier structure, with the collar fitting inside the annular space between the inner and outer corrugated metal pipes. This nested configuration allows the reinforcement to be integrated into the existing foundation without requiring complete reconstruction, thereby increasing overturning moment capacity while minimizing additional complexity.
Solution Approach 2:
The foundation is divided into functional segments: the existing tensionless pier structure with inner and outer CMPs, and the added reinforcement collar as a separate but integrated component. This segmentation allows the reinforcement to be added independently to existing structures, enabling strength enhancement without redesigning the entire foundation system.
2Stability of the object's composition
If reinforcement structures are added to reduce movement and deflection, then the structural stiffness is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The reinforcement collar is designed to be installed during the original construction phase while the foundation is still being built. The collar is positioned and secured to the inner and outer CMPs before the concrete is poured, allowing for preliminary assembly and adjustment before the structure hardens, thereby reducing later construction complexity.
Solution Approach 2:
Grout is used as an intermediary material to secure the reinforcement collar to the inner and outer corrugated metal pipes. The grout fills the gaps and bonds the collar to the existing structure, providing a simple and effective connection method that reduces construction complexity while achieving the desired stiffness enhancement.
3Reliability
If embedded shear steel and horizontal bolts are used to improve structural integrity, then the reliability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The reinforcement collar incorporates embedded shear steel and horizontal bolts at specific critical locations where structural integrity is most needed. Rather than uniformly distributing reinforcement throughout the entire structure, the collar concentrates strengthening elements at key interfaces and stress zones, thereby improving reliability while reducing overall manufacturing precision requirements.
Data Source
AI summary
A reinforced tensionless concrete pier foundation for supporting a tower and a method of constructing the same is provided, the foundation having an outer CMP and an inner CMP with an annular space therebetween in which a plurality of sleeved tower anchor bolts are embedded, and the pier foundation including at least one reinforcement structure that at least partly encircles the outer CMP to provide one or more of increased lateral stiffness, increased shear resistance and overturning (upset) moment capacity, reduced bending, displacement, and deflection of the top of the pier, and improved conditioning, containment, skin friction and lateral bearing capacity of the surrounding soil and/or rock substrate that supports the tensionless pier.