StiffWall®
Background
StiffWall® shear walls are designed to provide both lateral strength and
stiffness. Lateral strength is needed to resist horizontal loads due to
wind and earthquake forces. Properly designed and constructed
shear walls transfer horizontal forces to the next element in the load
path below them, such as other shear walls, floors, or foundations.
Lateral stiffness is needed to prevent the floors and roof from excessive
side-sway. When shear walls are stiff enough, they will prevent
floor and roof framing members from moving off their supports. In
addition, buildings with sufficient lateral stiffness will suffer less nonstructural
damage, further avoiding long-term degradation due to
cracking and water infiltration.
StiffWall® is manufactured to deliver the performance specifications of
the designer. Each component in the StiffWall® is selected to meet or
exceed both strength and stiffness requirements. The Steel Network
has optimized the design and fabrication of StiffWall® through a series of both component and full-scale
wall assembly tests, using state of the art techniques to measure performance. Simple connections
are recommended at www.steelnetwork.com to prevent sliding and uplift resistance.
StiffWall® is designed to carry loads concentrically from the point of applied loads to the foundation or
other termination point.
Planning Shear Walls
To develop an efficient shear wall layout several factors need to be considered:
- Shear walls should be equivalent in width and located symmetrically at all four exterior walls of a building,
- Provide interior shear walls when exterior walls cannot provide sufficient stiffness and strength,
- Provide interior shear walls when allowable span to width ratio for the floor or roof diaphragm is exceeded,
- Align shear walls vertically from the foundation to the roof diaphragm and strengthen areas to transfer loads when alignment is not
practical,
- The length of a shear wall dramatically influences the amount of allowable uplift loads necessitating greater widths for efficiency.
Stiff Wall® Design
Two StiffWall® systems are available; StiffWall® SW-R, a pre-assembled panel utilizing high-strength threaded rods in the wall cavity to provide
the shear resistance, and StiffWall® SW-S, a stick-build system that utilizes light gage straps on both sides of the wall for shear resistance.StiffWall® provides superior quality with high yield ASTM A653 steel and G-60 hot-dipped galvanized coating for long-term durability.
The stiffening effects of sheathing are not considered in StiffWall shear resistance values.
StiffWall® is specified using simple nomenclature indicating only essential design requirements for each shear wall element. The design is
ideal for job specific sizes with established load requirements.
Stiff Wall® Benefits That Add Value
StiffWalls are custom designed per project loading requirements. Simple attachments are made at corners through the innovative Boot system (examples here). Assembly instructions are available for installers here.
Templates are not required for hold-downs, eliminating unrealistic field procedures.
Flexible height, width and depth allow for maximum applicability.
Designed to satisfy maximum story drift requirements per IBC2000 and UBC 97.
Only mill certified high strength steel is used to maximize efficiency.
Plywood sheathing with fastener schedules and/or CMU shear walls are eliminated.
Inspection is limited to simple connections at corners.
Testing offered to verify calculations and exceed industry standards for sizes and loads.
Versatile design may be incorporated into steel, concrete and wood construction without additional costly parts.
Design flexibility, fast installation and maximum load carrying capacity.
Tested for multi-story application and capable of carrying loads present in 10 story buildings.
Studs inside the StiffWall® frame are spaced at 16” o.c. and manufactured for bearing and non-bearing wall studs.
Wall framing thickness (StiffWall® frame only) may vary from 3.5” to 8” in depth.
No welds or controlled inspections associated with welding.
Simplified anchoring system offers a practical attachment to foundations, through floors and at roof termination.
No reduction in shear wall capacity due to accidental holes or cuts in sheathing.
The SW-R (threaded rod system) is in the wall cavity to provide resistance to thermal conductivity and to facilitate smooth finishes.
The SW-S (strap system) is on the outside of the wall to facilitate electrical and pipe work in the wall cavity.
Pre-punched holes for electrical chase.
Allows 3 times the window space of plywood braced structures.
Distributed and delivered to the job site through local distribution.
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