Prefabricated Truss Segments for Lateral Load Transfer
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Solution Overview
Problem
Conventional building construction methods for lateral load-resisting wall segments are labor-intensive and prone to errors, leading to reduced lateral load-resisting capacity and increased risk of wall movement and failure due to the use of plywood nailed into diaphragms.
Innovation Solution
The development of prefabricated truss segments with truss plates and wood framing that can be easily assembled on-site, providing a stronger and more efficient means of transmitting lateral loads through a rigid framework, reducing the need for conventional shear walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plywood is nailed into diaphragms for lateral load resistance, then the wall segments can provide shear resistance, but the installation process becomes labor-intensive and error-prone
Solution Approach 1:
The wall segment is divided into modular components: pre-assembled truss segments with integrated plywood panels, standardized holdowns, and connection hardware. Each truss segment is a self-contained unit that can be manufactured off-site and assembled quickly on-site, eliminating the labor-intensive process of nailing plywood into diaphragms while maintaining lateral load-resisting capacity.
Solution Approach 2:
The truss segments, plywood panels, and connection hardware are pre-assembled and pre-positioned during manufacturing before delivery to the construction site. This preliminary assembly ensures proper alignment and connection, eliminating on-site installation errors and reducing labor requirements during construction.
2Ease of manufacture
If conventional nailing methods are used to attach plywood to diaphragms, then the wall segments can be assembled, but inaccurate nailing reduces lateral load-resisting capacity
Solution Approach 1:
Metal connection hardware and holdowns serve as intermediaries between the plywood panels and the diaphragm structure. These specialized connection elements provide reliable load transfer paths and are designed to work with the truss segments, ensuring consistent and accurate connection without relying on manual nailing precision.
Solution Approach 2:
The connection method is changed from mechanical nailing to a system using pre-engineered metal connectors and holdowns with standardized attachment points. This parameter change in the connection mechanism eliminates the variability and inaccuracy associated with manual nailing while maintaining assembly simplicity.
3Force
If plywood is nailed into diaphragms, then lateral loads can be transferred, but excessive wall movement occurs due to nail failure
Solution Approach 1:
The wall segment uses a composite construction combining wood truss members, plywood panels, and metal connection hardware. This composite system creates multiple load paths and connection points that distribute lateral forces more effectively, reducing stress concentration and minimizing wall movement while maintaining load transfer capability.
Solution Approach 2:
The design incorporates redundancy in the connection system with multiple holdowns and connection points distributed throughout the wall segment. This beforehand cushioning ensures that if one connection point fails or deforms, other connections maintain the structural integrity and prevent excessive wall movement.
Data Source
AI summary
The invention provides load-resisting segments (e.g., panels or frames for openings) for transmitting loads through a building structure. In the context of a wall, the load-resisting segments transmit shear loads downward to structural elements below the wall, such as to a building foundation. The load-resisting segments may comprise a truss configuration, i.e., an assembly of members forming a rigid framework. Each load-resisting segment can include web members and pairs of truss plates secured to sides of the segment to secure connections of the web members to each other and to other members. The wall segments can include beam-separation blocks that reduce truss plate failure by spacing apart the ends of two web members bearing against a chord or post to position the intersection point of the load paths of the web members with the load path of the chord or post. Some of the truss plates can include strips of material to provide additional resistance to tearing of the truss plate due to loads experienced by the truss plate. Some of the load-resisting segments, particularly frames for doors or windows, may include compression plates that prevent point-loading of studs or chords against transversely oriented members. For example, a truss frame may include compression plates between ends of its columns and surfaces of a header or sill structure.