Hollow-Core Slab Transition Structure for Lowered Regions
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Solution Overview
Problem
Existing concrete hollow-core slabs with lowered regions have reduced structural strength due to discontinuities and require thick lower layers to compensate, which increases weight.
Innovation Solution
A continuous, integral transition portion connects the lowered region with adjacent ribs and the upper layer, made of the same material, enhancing structural strength and allowing a thinner lower layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the lower layer is made thick to compensate for reduced structural strength in lowered regions, then structural strength is improved, but weight increases
Solution Approach 1:
The lower layer is segmented into a standard thickness region and a lowered region with reduced thickness. The lowered region is further divided into a first lowered portion and a second lowered portion, allowing different thicknesses in different locations to optimize both strength and weight.
Solution Approach 2:
Different regions of the lower layer are given different thicknesses based on local requirements. The lowered region has reduced thickness where space is needed for services, while the standard thickness is maintained in other areas to preserve structural strength. This local differentiation resolves the contradiction between overall strength and weight reduction.
2Strength
If the lower layer is made thick to maintain structural strength, then bending strength is improved, but weight increases
Solution Approach 1:
The lower layer is segmented into regions of different thickness, with the lowered region having reduced thickness. This segmentation allows the structure to maintain bending strength in critical areas while reducing weight in areas where full thickness is not required.
Solution Approach 2:
The lower layer exhibits local quality variations with different thicknesses in different regions. The standard thickness provides bending strength where needed, while the reduced thickness in the lowered region reduces overall weight without compromising structural integrity.
3Strength
If the lower layer is made thick to maintain structural strength, then shear strength is improved, but weight increases
Solution Approach 1:
The lower layer is segmented into standard and lowered regions with different thicknesses. This segmentation allows shear strength to be maintained in critical areas through the standard thickness regions while reducing weight in the lowered region where full thickness is not required.
Solution Approach 2:
Different regions of the lower layer have different thicknesses to provide local shear strength where needed. The standard thickness regions maintain shear strength, while the reduced thickness in the lowered region reduces overall weight.
4Weight of stationary object
If a thin lower layer is used to reduce weight, then weight is reduced, but structural strength decreases
Solution Approach 1:
The lower layer is segmented into standard thickness regions and a lowered region with reduced thickness. This segmentation allows weight reduction in the lowered region while maintaining structural strength in the standard thickness regions.
Solution Approach 2:
The lower layer has local quality variations where standard thickness provides structural strength and the reduced thickness reduces weight. This local differentiation allows simultaneous achievement of weight reduction and strength maintenance.
5Weight of stationary object
If a thin lower layer is used to reduce weight, then bending strength decreases, but weight is reduced
Solution Approach 1:
The lower layer is segmented into standard and lowered regions, allowing weight reduction in the lowered region while maintaining bending strength in the standard thickness regions through strategic thickness distribution.
Solution Approach 2:
Different regions have different thicknesses to provide local bending strength where needed. The standard thickness regions maintain bending strength, while the reduced thickness in the lowered region reduces overall weight.
6Weight of stationary object
If a thin lower layer is used to reduce weight, then shear strength decreases, but weight is reduced
Solution Approach 1:
The lower layer is segmented into standard and lowered regions, allowing weight reduction while maintaining shear strength in the standard thickness regions through strategic thickness distribution.
Solution Approach 2:
Different regions have different thicknesses to provide local shear strength where needed. The standard thickness regions maintain shear strength, while the reduced thickness in the lowered region reduces overall weight.
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
A concrete hollow-core slab (1) comprises an upper layer (3) which has an upper surface (4) and a lower surface (5), a lower layer (6) which has an upper surface (7) and a lower surface (8) and at least two ribs (9) which interconnect the upper layer (3) and the lower layer (6), hence forming an elongate channel (10) between the ribs (9), the upper surface (7) of the lower layer (6) and the lower surface (5) of the upper layer (3). The concrete hollow-core slab (1) has a lowered region (2) which has an upper surface (11) at a lower level than the lower surface (5) of the upper layer (3). A transition portion (12) located at a higher level than the lowered region (2) at a transition between the lowered region (2) and the upper layer (3) in longitudinal direction of the channel (10) interconnects the lowered region (2) and at least a portion of the ribs (9) adjacent to the transition portion (12). The transition portion (12), the ribs (9), the lowered region (2), the upper layer (3) and the lower layer (6) are made in one piece.