4. Importance of Selecting Proper Connectors and Fasteners for a Continuous Load Path
Buildings are exposed to numerous forces (loads), including those associated with wind events, floods, snow accumulation, and earthquakes. For a building to survive exposure to such forces, loads must be transferred through the building’s structure to the soils that support the building along what are typically referred to as load paths. Load paths consist of structural elements (e.g., beams, columns, bearing walls) and the components that connect these elements. In light-frame construction, structural elements are often connected with metal connectors and fasteners (fasteners include screws, bolts, and nails). Examples are shown in Figure 1.
Metal connectors are premanufactured components that are usually cut from flat steel sheets and formed into a shape to efficiently transfer loads from one structural element to another. The load capacities of metal connectors, often determined by the manufacturer through testing or analysis, are published for use by design professionals and contractors to meet the load requirements for their project.
Metal connectors and fasteners are important elements in transferring loads from natural hazards (e.g., flood, wind, seismic) through a building. Corrosion rates for metal are dramatically higher in coastal environments than in less harsh, non-coastal environments. Therefore, it is important to increase the corrosion protection for metal connectors and fasteners in coastal environments. See Section 6 for information on the causes of corrosion in coastal areas. Studies have shown that stainless steel and thick hot-dip galvanized (G185 or higher) metal connectors and fasteners improve corrosion protection. Selecting metal connectors and fasteners made of the same metal and either hot-dip galvanized or stainless steel will improve performance. See Section 8 for information on improving corrosion resistance.
Regardless of the metal that is selected, routine inspection is important to identify when replacement is necessary. See Section 9.2 for information on inspections.
Preservative-treated lumber, which is commonly used in many buildings, requires special attention when selecting connectors and fasteners. See Section 5.1.1.
