Column-Ceiling Node with Enlarged Cross-Sections for Load Transfer
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Solution Overview
Problem
The column-slab node in multi-storey reinforced concrete structures is a weak point for transferring vertical loads due to the lower strength of the concrete slab and discontinuity of longitudinal reinforcement, leading to potential load-bearing capacity and deformation issues, and existing solutions are either complex, expensive, or result in a loss of cross-sectional area and load-bearing capacity.
Innovation Solution
Enlarging the cross-sectional areas of the concrete columns at the upper and lower ends adjacent to the reinforced concrete slab, allowing for a smooth passage of reinforcement and tendons, while maintaining the usual design of slab reinforcement, and using high-strength or ultra-high-strength concrete to reduce the need for additional reinforcement, thereby enhancing load-bearing capacity without increasing the column area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the normal force of the upper concrete column is transferred through the reinforced concrete slab to the lower concrete column, then the load transfer path is established, but the load-bearing capacity is reduced due to the lower strength of the slab concrete compared to the column concrete
Solution Approach 1:
The patent introduces a steel structure (steel plate or steel profile) as an intermediary element between the upper and lower concrete columns. This steel mediator receives the normal force from the upper column and transfers it to the lower column, bypassing the weak slab concrete in the direct load path. The steel structure is embedded in the slab and provides a high-strength compression-loaded end plate joint that compensates for the lower strength of the slab concrete.
Solution Approach 2:
The patent creates a composite structure combining concrete columns with embedded steel reinforcement elements. The steel structure (end plates, steel profiles) works together with the concrete slab to form a composite joint system that leverages the high compressive strength of steel to overcome the limitations of the slab concrete, achieving load-bearing capacities comparable to the column-strength concrete.
2Productivity
If story-high precast columns are used, then construction speed is improved and assembly is simplified, but the longitudinal reinforcement cannot be extended continuously through the column-ceiling joint into the upper concrete column
Solution Approach 1:
The steel structure serves as a mediator that connects the reinforcement of the lower column to the upper column through the slab. The longitudinal reinforcement from the lower column can be anchored into the steel structure (steel plate or profile), which then provides continuous reinforcement path to the upper column, maintaining structural integrity while allowing precast column assembly.
Solution Approach 2:
The patent applies different reinforcement strategies in different locations: in the highly stressed areas at the column-slab joint, a steel structure with embedded reinforcement is used to ensure continuity, while the rest of the slab can use conventional reinforcement. This local enhancement at the joint maintains overall reinforcement continuity without requiring changes to the entire column or slab design.
3Strength
If a steel structure is incorporated into the column-slab joint to improve load-bearing capacity, then the load transfer is enhanced, but the manufacturing complexity and construction cost increase
Solution Approach 1:
The patent extracts the essential function of load transfer from a complex three-dimensional steel framework and reduces it to a simpler two-dimensional steel plate or linear steel profile embedded in the slab. This simplified steel structure maintains the load-bearing capacity while significantly reducing manufacturing complexity and construction cost compared to full 3D steel joints.
Solution Approach 2:
The patent uses relatively simple, inexpensive steel plates or profiles that can be easily manufactured and installed as temporary-looking elements within the slab. These simple steel components provide the necessary structural function without requiring complex fabrication, making them economically viable compared to elaborate steel joint systems.
4Strength
If end plates are welded to the longitudinal reinforcement at the top of the lower column and bottom of the upper column, then a compression-loaded joint is created, but construction tolerances require high compensation costs
Solution Approach 1:
The steel structure in the slab acts as a cushioning element that absorbs and compensates for construction tolerances. The steel plate or profile provides a forgiving interface that can accommodate minor misalignments between the precast columns and slab, eliminating the need for expensive tolerance compensation measures such as thick grout layers or adjustable connection details.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Column-ceiling node (1) for a reinforced concrete ceiling (11) and two prefabricated concrete columns (2, 3, 4) in storey construction, wherein the upper end (7) of the lower concrete column (3) and/or the lower end (8) of the upper concrete column (4) are or is arranged adjoining the reinforced concrete ceiling (11), wherein the column axes (5) of the concrete columns (3, 4) extend substantially along a common straight line. The column-ceiling node (1) has a cross section in the region of the upper end (7) of the lower concrete column (3) that is greater than a cross section of the central half (6) of the longitudinal extent of the lower concrete column (3), and has a cross section in the region of the lower end (8) of the upper concrete column (4) that is greater than a cross section of the central half (6) of the longitudinal extent of the upper concrete column (4).