Floating Purlin Hanger for Thermal Expansion Management
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Solution Overview
Problem
As buildings grow larger and use longer metallic through-fastened cladding panels, thermal expansion causes the panels to lengthen, leading to structural stress and potential damage as the cladding and framing push in opposite directions, with existing solutions like thermal splices being time-consuming and costly.
Innovation Solution
A sliding or 'floating' purlin hanger system is introduced, allowing purlins to move slidably with respect to the roof trusses, thereby enabling the roof cladding to 'float' and accommodate thermal expansion without exerting damaging forces on the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long metallic cladding panels are used to reduce the number of joints and improve aesthetics, then the panel length increases, but thermal expansion causes excessive stress on the roof structure
Solution Approach 1:
The purlin hanger is designed with a sliding mechanism that allows the purlin to move dynamically along the roof truss in response to thermal expansion. The slot in the hanger body provides a guided path for movement, transforming the system from static to dynamic to accommodate dimensional changes without stress accumulation
Solution Approach 2:
The sliding purlin hanger acts as an intermediary element between the rigid roof truss and the metallic cladding panel. It mediates the thermal expansion by providing a controlled sliding interface, allowing the panel to expand while maintaining structural support and preventing direct stress transmission to the truss
2Stability of the object's composition
If traditional fixed purlin hangers are used to securely attach purlins to roof trusses, then structural stability is maintained, but thermal movement of long panels causes damage to cladding or structure
Solution Approach 1:
The hanger transitions from a fixed rigid connection to a dynamic sliding connection. The slot geometry provides guided movement while maintaining vertical support, allowing the system to adapt to thermal expansion while preserving structural integrity through controlled motion rather than rigid constraint
Solution Approach 2:
The invention converts the harmful thermal expansion force into a beneficial controlled sliding motion. Instead of resisting the expansion and causing damage, the system allows the panel to expand along the slot path, transforming a potentially destructive force into a manageable movement that maintains structural health
3Stress or pressure
If thermal splices are used to mitigate thermal movement, then thermal stress is reduced, but installation time and material cost increase significantly
Solution Approach 1:
The invention extracts the thermal management function from the cladding panel system and places it in the support system (purlin hanger). By moving the expansion accommodation mechanism from the panel joints to the support structure, the complex thermal splice operations are eliminated and replaced with a simple sliding interface
Solution Approach 2:
The sliding purlin hanger serves as an intermediary that handles thermal expansion at the support level rather than requiring complex splice details at the panel level. This simplifies the installation process by eliminating the need for precise thermal splice fabrication and installation while still providing effective stress management
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 effectively manages thermal movement of metallic cladding panels at low force levels, preventing damage to the cladding or roof structure, even with long panels, and eliminates the need for unsightly and costly thermal splices.
Implementation Method 1
Steel, like most materials, expands and contracts as it warms and cools. Metals in particular tend to have large coefficients of thermal expansion. Thermal expansion occurs in all directions.
Data Source
AI summary
The present invention relates to a roof mounting system for roof structures having purlins supported on roof trusses, the roof mounting system including a purlin hanger having at least one purlin support and mounting bracket for securing the purlin hanger to a truss in sliding relation.