Pre-cast Concrete Wall Truss Ledge Below-Grade Support
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Solution Overview
Problem
Conventional pre-cast concrete wall systems are not configured to support building floor structures below grade level, which is required in certain regions like the Southwest United States, where the floor structure needs to be recessed below grade for a uniform finished floor level.
Innovation Solution
A pre-cast concrete wall system incorporating a vertical truss ledge that projects above the upper bond beam to provide a support surface for floor trusses, with galvanized steel stud facings and insulated access holes for wiring and plumbing, and monolithic pouring for enhanced strength, allowing the system to support floor structures at a below-grade position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional pre-cast concrete wall systems are used with upper bond beam, then the wall structure is simple and easy to manufacture, but the wall structure cannot support building floor below grade level
Solution Approach 1:
The wall panel is segmented into distinct functional zones: footer beam at the bottom, upper bond beam at the top, and vertical truss ledge projecting from the bond beam. This segmentation allows each component to serve its specific structural purpose while maintaining overall system adaptability for below-grade floor support
Solution Approach 2:
The vertical truss ledge extends upward from the upper bond beam in a vertical dimension, creating a new support plane above the traditional bond beam level. This dimensional extension enables floor truss support at below-grade positions without complicating the horizontal wall assembly process
2Adaptability or versatility
If the wall structure is modified to support floor below grade, then adaptability improves, but manufacturing complexity increases
Solution Approach 1:
The vertical truss ledge is merged with the upper bond beam as an integrated concrete element, both formed and poured as part of the same pre-cast wall panel. This merging eliminates the need for separate components or field assembly, maintaining ease of manufacture while achieving below-grade support capability
Solution Approach 2:
The upper bond beam serves multiple functions: it provides the traditional top structural element of the wall panel and simultaneously supports the vertical truss ledge that anchors floor trusses. This multi-functionality allows a single manufactured component to address both traditional and below-grade support requirements
3Reliability
If vertical truss ledge is added to project above upper bond beam, then floor support capability below grade is achieved, but wall panel complexity increases
Solution Approach 1:
The wall panel employs composite construction with galvanized steel stud facings embedded in and bonded to the concrete vertical ledge and bond beam. This composite steel-concrete structure enhances the reliability and load-bearing capacity of the floor support system while maintaining a unified pre-cast panel design
Data Source
AI summary
A pre-cast concrete wall system that incorporates a truss ledge for positioning a building floor system at a below-grade location. The truss ledge is defined by a vertical wall formed as a continuation of the exterior wall of the wall panel extending from the footer beam to the upper bond beam and projecting vertically above the upper bond beam to provide a support surface for the building floor members. A floor truss system can be supported on the upper bond beam with the truss ledge forming a concrete below-grade surface externally of the floor trusses. Galvanized steel stud facings incorporating fold-up reinforcing bar supports are used on the interior surface of the vertical wall beams. Insulated access holes are formed through the vertical beams for the passage of wiring and plumbing behind the wall finish to be fastened to the stud facings.