General
Lateral Systems
Little did we know when we introduced our first holdown in 1966 that our product innovations would lead us to solutions that can help hold together five-story buildings during an earthquake or allow builders to more easily retrofit structures and install larger window and door openings in homes. Our offering of lateral-force resisting systems, including Timber Portal Frame System and new Strong-Rod™ Systems, gives designers and engineers added design flexibility in timber-frame construction and the confidence that almost anything is possible.
A History of Testing, Innovation Drives Today's Performance
The Simpson Strong-Tie commitment to product design and testing over the years has resulted in us taking a whole-systems approach to building design. One of the key milestones that launched us down this path was the development of our first factory-built wood shearwall — the Strong-Wall®. Our prefabricated shearwalls improve the quality, consistency and performance of shearwalls in the field.
Strong-Wall® Site-Built Portal Frame System
The latest addition to the Strong-Wall family is our new Strong-Wall® site-built portal frame system (PFS). The PFS is a kit of parts that provides designers, engineers and builders in prescriptive markets with an easy way to meet code-required wall-bracing requirements for garage portal frames or other wide openings.
- Narrow wall width for wide openings
- Easy on-site assembly
- Cost-effective bracing solution
- Equivalent performance to longer braced-wall lengths
Strong-Rod™ Systems
Simpson Strong-Tie Strong-Rod™ Systems have become a popular continuous rod tiedown solution for light-frame, multi-story timber construction. Our Anchor Tiedown System for Shearwall Overturning Restraint and our Uplift Restraint System for Roofs address many of the design challenges specifically associated with multi-story buildings that must withstand seismic activity or wind events.
Strong-Rod™ ATS solutions address the many factors that must be considered during design to ensure proper performance against shearwall overturning — such as rod elongation, timber shrinkage, construction settling, shrinkage-compensating device deflection, incremental loads, bearing-plate bending, cumulative tension loads and anchorage.
Why Continuous Rod Tiedown Systems?
Seismic and wind events are serious threats to structural integrity and occupant safety. All timber-framed buildings need to be designed to resist shearwall overturning and roof-uplift forces. For one- and two-storey structures, connectors such as straps, hurricane ties and holdowns have been the traditional answer. With the growth in mid-rise, timber-framed structures, however, rod systems have become an increasingly popular lateral and uplift restraint solution.
Multi-storey structures present complicated design challenges. Frequently the structures have larger windows and door openings, providing less space for traditional restraint systems. For all these reasons there is increased need for restraint systems that can meet multi-storey structural demands without sacrificing installation efficiency or cost considerations.
Continuous rod tiedown systems are able to answer these demands by restraining both lateral and uplift loads, while maintaining reasonable costs on material and labour. Instead of using metal connector brackets as in a holdown system, continuous rod tiedown systems consist of a combination of rods, coupler nuts, bearing plates and shrinkage-compensation devices. These all work together to create a continuous load path to the foundation.
Tension Forces Resisted by Continuous Rod Tiedown Systems
Continuous rod tiedown systems are used to resist two types of tension forces — shearwall-overturning forces and uplift forces on roofs.
One type of tension force is a result of lateral (horizontal) forces due to a wind or seismic event. This force occurs at the end of shearwalls and its magnitude increases at lower levels as it accumulates the tension force from each level or shearwall above.
Anchor Tiedown System for Shearwall Overturning Restraint
A continuous load path is essential to a building's structural performance. Directing the diaphragm loads from roofs, floors and walls to the foundation in a prescribed continuous path is a widely accepted method to prevent shearwall overturning.
- High load capacities required for mid-rise timber construction
- Low deflection to help limit shearwall drift
- Steel tension elements of the structural lateral-force resisting system
- Backed by years of rod-system performance testing
Because timber shrinkage and settlement can create a gap between the steel nut and bearing plate as shrinkage accumulates up the building, take-up devices must be used with most timber structures greater than two storeys tall at each level to ensure optimum system performance.
