Height-Adjustable Suspended Slab Foundation
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Solution Overview
Problem
Existing structural foundation technologies, such as slab-on-grade and structurally suspended slabs, face challenges in cost, maintenance, and adaptability, with slab-on-grade being cost-effective but maintenance-intensive and litigation-prone, and suspended slabs being costly and labor-intensive with no provision for future height adjustments.
Innovation Solution
A system that forms a slab on a ground surface and then lifts it using mechanical lifting mechanisms, allowing for adjustable height, combining the cost-effectiveness of slab-on-grade with the isolation benefits of suspended slabs, and enabling future adjustments or repairs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a slab-on-grade foundation is used, then construction cost is reduced, but maintenance intensity increases and reliability deteriorates due to soil dependency
Solution Approach 1:
The foundation system is segmented into discrete support points (piers or posts) rather than continuous ground contact. The slab is divided into regions supported by individual elements, allowing each support to be independently adjusted or replaced without affecting the entire foundation structure.
Solution Approach 2:
An intermediary lifting mechanism is introduced between the slab and the support base. This mediator allows the slab to be elevated and decoupled from direct soil contact, providing a buffer that protects against soil movement while maintaining structural support. The intermediary enables future adjustment of slab height independent of the support base.
2Reliability
If a structurally suspended slab is used, then reliability improves by isolating from soil movement, but construction cost and device complexity increase
Solution Approach 1:
The complex temporary formwork and void box systems traditionally required for suspended slabs are extracted and replaced with a simpler permanent support base structure. The essential function of creating a void space is achieved through direct elevation of the slab on adjustable supports rather than through elaborate temporary construction elements.
Solution Approach 2:
The support base serves multiple functions: it provides structural support, enables slab elevation, allows for future height adjustment, and facilitates slab removal or replacement. This multi-functional design eliminates the need for separate temporary formwork systems that would otherwise be required during construction.
3Reliability
If a structurally suspended slab is used, then isolation from soil movement is achieved, but adaptability deteriorates due to no provision for future height adjustments
Solution Approach 1:
The foundation system transitions from a static, fixed-height structure to a dynamic, adjustable system. The lifting mechanism incorporates movable components that allow the slab height to be changed after construction, enabling adaptation to settlement, expansion, or repair needs without demolishing the entire foundation.
Solution Approach 2:
The lifting mechanism is pre-installed and integrated into the foundation structure during initial construction, rather than being added as a retrofit. This preliminary incorporation ensures that adjustment capability is built-in from the start, avoiding the need for complex future interventions while maintaining structural integrity.
4Reliability
If traditional suspended slab construction is used, then isolation from soil movement is achieved, but productivity decreases due to labor intensity and extended construction time
Solution Approach 1:
The support bases are installed and positioned before the slab is poured, and the lifting mechanisms are pre-positioned within the concrete. This preliminary preparation eliminates the need for complex temporary formwork erection and removal during construction, significantly reducing on-site labor time and accelerating the construction schedule.
Solution Approach 2:
The temporary formwork function and permanent support structure are merged into a single integrated system. The support bases serve both as construction formwork during pouring and as permanent structural elements after curing, eliminating redundant construction steps and reducing overall project duration.
Data Source
AI summary
To form a new structurally suspended slab or to raise an existing slab for a structural foundation, structural supports are placed in the ground. The structural supports are attached to lifting assemblies, which are also installed in the slab. Actuation of the lifting assembly allows the slab to be raised and/or lowered, thereby forming a suspended slab over a void of a desired size. Existing slabs may be repaired using similar techniques.