Composite Joist Floor System Shear Transfer
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Solution Overview
Problem
Existing composite joist floor systems in large buildings are not optimized to integrate fire safety, acoustics, and vibration considerations systematically with the building's support structure, leading to suboptimal performance in load carrying capacity and vertical deflection.
Innovation Solution
The implementation of a composite joist floor system featuring corrugated steel decking with self-drilling, self-tapping stand-off screws that transfer shear between steel joists and a concrete slab, combined with z-shaped closures and pour stops for enhanced fire protection and stiffness, allowing the concrete slab to act as a stronger upper chord.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional non-composite floor systems are used with wide flange beams or steel joists, then the construction is simpler, but the load carrying capacity is lower and vertical deflection is greater
Solution Approach 1:
The patent combines steel joists with concrete slabs to form a composite floor system. The steel joists provide tensile strength while the concrete slab provides compressive strength, creating a structurally superior composite element that exceeds the capabilities of either material alone. This composite construction directly addresses the need for higher load carrying capacity.
Solution Approach 2:
The patent merges the steel joist system with the concrete floor slab into an integrated composite structure. By combining these two separate structural elements into a unified system that acts together, the design achieves greater load carrying capacity and reduced deflection compared to non-composite systems.
2Strength
If composite construction with welded shear studs is used, then the load carrying capacity increases, but the manufacturing complexity and fire safety concerns increase
Solution Approach 1:
The patent replaces the traditional welded shear stud connection system with a mechanical attachment system using pre-formed steel connectors. These connectors mechanically attach the concrete slab to the steel joists without requiring welding operations, thereby maintaining composite action while eliminating the complexities and safety concerns associated with welding in the field.
3Strength
If the concrete slab is used as upper chord, then the load carrying capacity increases, but the fire protection requirements become more stringent
Solution Approach 1:
The patent incorporates fire-resistant materials and protective measures during the design and construction phases. By pre-planning fire protection strategies such as using fire-resistant concrete mixes, appropriate slab thicknesses, and protective coatings on steel components, the system achieves both high load carrying capacity and adequate fire safety without requiring additional retroactive protection measures.
4Object-affected harmful factors
If traditional floor systems are used, then the acoustic performance is adequate, but the vibration control is insufficient
Solution Approach 1:
The composite steel-concrete construction inherently provides superior vibration control compared to traditional floor systems. The mass of the concrete slab combined with the stiffness of the steel joists creates a system with higher natural frequencies and better damping characteristics, effectively reducing vibration from foot traffic and other dynamic loads.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration results in a composite system with increased load carrying capacity and reduced vertical deflection compared to non-composite floor systems, while also providing improved fire safety and acoustic attenuation.
Implementation Method 1
These stand-off screws provide the required shear transfer between the joist and concrete slab to form a composite floor system
Implementation Method 2
The placed concrete encapsulates the upper non-threaded shank portions of the self-drilling, self-tapping, stand-off screws and the end of the joists
Implementation Method 3
the resultant system comprised of steel joists, steel decking, stand-off screws, and concrete, act together to form a composite system with greater load carrying capacity and less vertical deflection
Implementation Method 4
a combination of z-shaped closures and/or pour stops provide forming for the concrete
Data Source
AI summary
Embodiments of the present invention provide systems for connecting a flooring system to a vertical wall. In one embodiment the building structure includes a floor comprising a cementitious slab and a wall supporting at least a portion of the cementitious slab. A plurality of stand-off fasteners extend from the top of the wall into the cementitious slab and are configured to transfer forces between the cementitious slab and the wall. The stand-off fasteners comprise a lower portion and an upper stand-off portion. The lower portion is operatively coupled to the top of the wall, and the upper stand-off portion extends above the top of the wall and is encapsulated within the cementitious slab. In some embodiments, at least a portion of the lower portion is heat treated to a higher degree of hardness relative to the remainder of the stand-off screw.