Grooved Prefabricated Floor Elements for Negative Moment Resistance
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Solution Overview
Problem
Existing structural floors made of precast concrete elongated elements face inefficiencies in resisting negative moments, require extensive shoring, and have issues with bonding and differential shrinkage, leading to cracks and increased construction time and cost.
Innovation Solution
A prefabricated floor element with continuous upper grooves on the upper planar face to transmit tension forces and resist negative moments, combined with lower and lateral tabs or grooves to manage vertical shear forces and prevent differential shrinkage, allowing for efficient bonding and reduced construction time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If precast concrete elongated elements are used for structural floors, then construction speed and initial structural strength are improved, but the ability to resist negative moments is insufficient and extensive shoring is required
Solution Approach 1:
The precast floor element is segmented with continuous transversal grooves created on its upper face, dividing the concrete mass into sections that can interlock with the cast-in-situ topping. This segmentation allows the precast element to effectively resist negative moments while maintaining construction speed advantages
Solution Approach 2:
The system combines precast concrete elements with cast-in-situ concrete topping to create a composite structural floor. The precast element provides initial strength and speed, while the composite action with the topping through the grooves enables effective negative moment resistance
2Strength
If bonding systems are used to connect precast and cast-in-situ concrete, then structural integrity is improved, but differential shrinkage causes cracks and reduces reliability
Solution Approach 1:
Instead of attempting to bond the entire surface, the invention creates localized bonding zones through continuous transversal grooves. These grooves concentrate the bonding action at specific locations where mechanical interlock occurs, reducing the overall differential shrinkage stresses while maintaining effective connection
Solution Approach 2:
The continuous transversal grooves segment the bonding interface, creating multiple small bonding zones rather than one large continuous bond. This segmentation allows differential movement in each zone without propagating cracks across the entire interface, improving reliability
3Stability of the object's composition
If extensive shoring is used to support structural floors during construction, then structural stability is improved, but construction time and cost increase
Solution Approach 1:
The precast floor elements are prepared in advance with continuous transversal grooves created on their upper faces before installation. This preliminary action ensures that when the elements are erected and topped with cast-in-situ concrete, the bonding mechanism is already in place to provide immediate structural stability, reducing or eliminating the need for extensive shoring during construction
Data Source
AI summary
Prefabricated floor element (1) having an elongated shape wherein a longitudinal direction (X), a transversal direction (Y), a height direction (Z), two end faces (11) which delimitate the element (1) in the longitudinal direction (X), two lateral faces (12) which delimitate the element (1) in the transversal direction (Y), a lower face (13) and an upper planar face (14) that delimitate the element (1) in the height direction (Z) are defined, which comprises transversal continuous upper grooves (15) on the upper planar face (14) or lateral grooves (26) on the lateral faces (24), the lateral grooves (26) extending from the lower tab (TS) to the upper planar face (24). The invention also relates to a structure comprising such prefabricated floor element (1) and further comprising a linear supporting element (LS) which supports one end of the prefabricated floor element.