Composite Joist Floor System Shear Transfer
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Solution Overview
Problem
Existing balcony structures in large-scale buildings lack an integrated design that optimizes fire safety, acoustics, and vibration considerations, with prior designs not effectively addressing these issues systematically.
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 concrete slabs, combined with z-shaped closures and pour stops for enhanced structural integrity and fire protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional joist and deck floor systems are used, then construction simplicity is maintained, but fire safety, acoustics, and vibration performance are not optimized
Solution Approach 1:
The patent combines multiple previously separate components (joists, decking, fire protection layers, acoustic insulation, and vibration damping elements) into an integrated composite floor system where all elements work together as a unified structure, thereby improving fire safety, acoustics, and vibration performance simultaneously without proportionally increasing complexity
Solution Approach 2:
The patent employs composite construction by layering different materials (steel joists, metal decking, concrete or gypsum fire protection layers, acoustic insulation materials) to create a multi-functional floor system that achieves enhanced fire safety, acoustic attenuation, and vibration control through material composition rather than单一材料
2Strength
If composite construction with shear studs is used, then load carrying capacity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes the self-weight of the concrete or gypsum fire protection layer to automatically achieve composite action with the steel joists and decking, eliminating the need for manually installed shear studs or mechanical connectors, thereby maintaining high load carrying capacity while significantly reducing construction complexity
Solution Approach 2:
The patent introduces the fire protection layer (concrete or gypsum) as an intermediary element that serves dual purposes: providing fire safety protection and simultaneously acting as the shear transfer mechanism between steel components, replacing traditional shear studs and simplifying the construction process
3Strength
If heavier floor systems are used, then load carrying capacity increases, but structural weight increases
Solution Approach 1:
The patent employs composite construction by layering different materials (steel joists, metal decking, concrete or gypsum fire protection layers, acoustic insulation materials) to create a multi-functional floor system that achieves enhanced fire safety, acoustic attenuation, and vibration control through material composition rather than increasing overall weight
Solution Approach 2:
The patent optimizes the thickness and density parameters of each layer (steel joist spacing, decking gauge, fire protection layer thickness, acoustic insulation density) to achieve the required load carrying capacity with minimum weight, rather than uniformly increasing the weight of all components
4Reliability
If integrated design is implemented, then fire safety, acoustics, and vibration performance are optimized, but design complexity increases
Solution Approach 1:
The patent designs each layer to serve multiple functions: the fire protection layer provides both fire safety and shear transfer, the acoustic insulation layer provides both noise control and thermal insulation, and the composite action provides both structural strength and vibration damping, thereby achieving multiple performance goals through a unified design approach rather than separate systems
Solution Approach 2:
The patent merges previously separate design considerations (fire safety design, acoustic design, vibration control design, and structural design) into a single integrated composite floor system design, where all performance requirements are addressed simultaneously through the configuration and material selection of the composite layers, reducing the need for multiple separate components
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 solution results in a stronger, lighter, and more economical flooring system with improved load-carrying capacity and reduced vertical deflection, while also providing better fire safety and acoustic attenuation.
Implementation Method 1
Self-drilling, self-tapping, stand-off screws are spaced along the length of the joist, aligned with the deck corrugations. 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 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 than a non-composite floor system.
Implementation Method 3
a combination of z-shaped closures and/or pour stops provide forming for the concrete. A z-shaped closure is provided having a vertical face, an upper horizontal flange, and a lower horizontal flange.
Implementation Method 4
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.
Data Source
AI summary
Systems are provided for use in balcony structures. The system includes a joist comprising an upper chord and a lower chord separated by a web. One end of the joist is supported by a supporting member and a cantilevered balcony extends generally perpendicularly from the supporting member. The cantilevered balcony comprises a cementitious balcony slab extending from a cementitious floor slab. The cementitious floor slab includes a backspan region extending from the top of the supporting member opposite the cementitious balcony slab. A portion of the joist in the backspan region comprises a decking supporting member coupled to the web. The joist in the backspan region supports decking using the decking supporting member; however, the joist beyond the backspan region supports decking above the upper chord. In this way, the cementitious floor slab in the backspan region is thicker than the cementitious floor slab beyond the backspan region.