Precast Concrete Dome Segments for Elevated Water Tanks
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Solution Overview
Problem
Conventional construction of concrete domes in composite elevated water storage tanks requires expensive and risky formwork, as well as extensive labor, due to the need for complex formwork and high elevations.
Innovation Solution
A method involving wedge-shaped concrete floor segments cast near grade or off-site, lifted and assembled over a ringbeam to form a dome shape, eliminating the need for complex formwork and reducing labor risks, with segments that can be curved or linear to match various dome profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cast-in-place method is used to construct the structural dome, then the dome can be built continuously, but expensive and complicated formwork must be erected and raised to high elevations
Solution Approach 1:
The dome is divided into multiple precast concrete segments that are manufactured separately at ground level and then assembled on the tower. Each segment is a self-contained unit with integrated reinforcement and formwork features, eliminating the need for large-scale elevated formwork structures. The segments are stacked and connected to form the complete dome shell.
Solution Approach 2:
The concrete segments are pre-cast at ground level in controlled conditions, allowing for preliminary preparation of reinforcement, formwork, and concrete mixing without the hazards of high-elevation work. This preliminary manufacturing phase eliminates the need to erect and raise complex formwork to elevated positions during actual dome construction.
2Ease of manufacture
If cast-in-place method is used to construct the structural dome, then the dome structure can be built, but extensive labor is required at high elevations increasing injury risk
Solution Approach 1:
By segmenting the dome into precast units, the hazardous work of concrete pouring, reinforcement placement, and formwork maintenance at high elevations is eliminated. All labor-intensive tasks are performed at ground level during segment manufacturing, and only lightweight segment handling and assembly are required at elevation, significantly reducing injury risk.
Solution Approach 2:
The precast segments are designed as self-contained units with embedded reinforcement, formwork features, and connection elements. This self-service design eliminates the need for workers to perform complex tasks at elevated positions, as the segments arrive ready-to-assemble with all necessary components integrated.
3Strength
If cast-in-place method is used to construct the structural dome, then the dome can be built monolithically, but expensive formwork must be erected and lowered using heavy equipment
Solution Approach 1:
The monolithic dome structure is achieved through carefully detailed connections between precast segments. The segments are designed with interlocking features, grout joints, and reinforcement continuity that create a unified structural behavior comparable to cast-in-place construction, but without requiring expensive formwork erection and dismantling equipment.
Solution Approach 2:
The formwork function is merged into the precast segment manufacturing process at ground level, where it can be reused multiple times for producing different segments. This eliminates the need for dedicated elevated formwork equipment, as the formwork becomes an integral part of the segment production system rather than a separate temporary structure.
Data Source
AI summary
A liquid storage tank has a tower section. A tank shell above the tower section encompasses a tank volume that has a capacity of at least 100,000 U.S. gallons. A reinforced ringbeam at the top of the tower section surrounds an internal area that withstands the downward force of the liquid. The ringbeam has at least one supporting face that resists downward forces. A dome sits on the supporting face and essentially covers the internal area. The dome is made of a series of laterally adjacent dome where each dome segment has an inner end that is positioned above an outer end.