Screw Receptacle Rough Underside Shear Force Transmission
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Solution Overview
Problem
Existing methods for fastening concrete elements to support structures, particularly in composite wooden and concrete structures, face challenges in efficiently transferring shear forces and require on-site construction due to the weight of concrete, limiting the reuse of materials and increasing production time.
Innovation Solution
A screw receptacle with a wedge-shaped body featuring a rough surface on its underside, which increases friction and allows for efficient force transmission through both non-positive and form-fitting connections, enabling the use of fewer screws and reducing the need for extensive on-site construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional screw connection is used to fasten concrete elements to support structures, then the connection can be made, but the shear force transmission is insufficient and requires more screws or higher preload
Solution Approach 1:
The underside of the screw receptacle body is provided with a rough surface in specific areas where force transmission is critical. This localized roughening increases friction and mechanical interlocking at the contact points between the concrete element and support structure, thereby improving shear force transmission without requiring changes to the entire connection system.
Solution Approach 2:
The surface roughness parameter of the receptacle body is modified by providing a rough surface with specific characteristics (average roughness depth of at least 1 mm, preferably at least 3 mm, and particularly at least 5 mm). This parameter change transforms the contact interface from smooth to rough, increasing frictional resistance and mechanical interlocking to improve force transmission efficiency.
2Reliability
If concrete elements are cast on-site to meet sound insulation and fire protection requirements, then the structural requirements are met, but the construction time is considerable due to concrete setting time
Solution Approach 1:
The screw receptacles are pre-installed in the support structure before the concrete element is cast. This preliminary action allows the connection elements to be positioned and secured in advance, enabling the concrete element to be pre-fabricated or quickly assembled on-site without waiting for extended setting periods, thus reducing overall construction time while maintaining structural reliability.
3Strength
If the concrete element is permanently fixed to the support structure, then the connection strength is maximized, but the ability to separate and reuse materials is lost
Solution Approach 1:
The connection system is designed to be dynamically adjustable between fixed and separable states. The rough surface provides sufficient friction and mechanical interlocking for strong permanent fixation during use, but the same rough surface characteristics allow for controlled separation when dismantling is required, enabling material reuse while maintaining connection strength during the service life of the structure.
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
The screw receptacle effectively transfers shear forces, allowing for the reuse of concrete elements and support structures, and reduces production time by enabling prefabricated concrete elements to be efficiently connected to wooden supports, enhancing both stability and ease of dismantling.
Implementation Method 1
This rough surface results in increased friction at the contact point with the supporting structure
Implementation Method 2
the rough surface can also be pressed into the supporting structure, particularly a wooden beam, so that the force transmission is not only frictional, as is usual with screw connections, but also form-fit
Data Source
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AI summary
The invention relates to a screw receptacle (1) for the detachable fastening of a concrete element (21) to a support structure (18), comprising a body (2), in particular a wedge-shaped body, with an opening (8), wherein the screw receptacle (1) can be cast with concrete to form a concrete element (21) and a channel for inserting a screw is defined at least partially through the opening (8) of the body (2), so that the concrete element (21) and the body (2) can be connected to the support structure (18) by means of the screw in a force-fit manner.According to the invention, to improve force transmission between the concrete element (21) and the support structure (18), a lower surface (3) of the body (2), which faces the support structure (18) when it is attached, is formed at least partially with a rough surface (7), wherein the rough surface (7) preferably has a mean roughness depth of at least 1 mm, more preferably at least 3 mm, and in particular at least 5 mm. Furthermore, the invention relates to a method for the detachable attachment of a concrete element (21) to a support structure (18).