![]() Bolted Top PlateĪs an alternate to the roof truss anchor, a bolted top plate may be used for the roof to wall connection (see Figure 5) however, anchor bolt spacing must be reduced (24 in. Additionally, the nail area available for the hurricane clip is limited by the thickness of the top plate. Often, the direct embedded roof truss anchor method of connecting the roof to walls is preferred over the bolted top plate and hurricane clip method, as it generally has greater capacity and fewer connections. In addition to being rated for uplift, the anchor must be rated for horizontal forces parallel to the wall (in-plane) and perpendicular to the wall (out-of-plane). The required anchor load capacity depends on the design wind speed as well as the roof truss span. ![]() 5) for standard hook requirements.įigure 4 shows a typical roof truss anchor cast into the bond beam of a concrete masonry bearing wall. See Steel Reinforcement for Concrete Masonry, TEK 12-4D (ref. If the wall was designed assuming Grade 40 and Grade 60 was used for construction, however, the 40 bar diameter lap splice may still be used. 1) for Grade 40 reinforcement and 48 bar diameters for Grade 60 reinforcement. Using allowable stress design, a splice length of 40 bar diameters is required by Building Code Requirements for Masonry Structures (ref. Reinforcement must be properly spliced to provide load path continuity. See Figure 1 for a summary of reinforcement requirements (ref. Longer shear segments are more effective and are recommended where possible or required by design. Each of the exterior walls on all four sides of the building and all interior walls designed as shear walls must have at least one 2 ft (610 mm) minimum section of wall identified as a shear segment to resist the high lateral loads. In addition to a continuously reinforced bond beam at the top of the wall around the entire perimeter of the building, vertical reinforcement must be placed throughout a wall to resist the high uplift loads and provide continuity, including: at corners and wall intersections on each side of openings wider than 6 ft (1,829 mm) at the ends of shear segments and where girders or girder trusses bear on the concrete masonry wall (refs. The reader is referred to references 7 through 9 for more information on preventing water penetration in concrete masonry walls. Note that water penetration details are not specifically highlighted in the following details. In coastal areas, corrosion protection is especially important due to the corrosive environment. Note that in order for connectors to provide their rated load capacity, they must be installed according to the manufacturer’s or building code specifications. Proper detailing and installation of mechanical connectors is necessary for maintaining continuous load paths. If one part of the load path fails or is discontinuous, building failure may occur. This allows wind uplift forces on the roof to be safely distributed through the walls to the foundation. ![]() A primary goal for buildings subjected to high winds is to maintain a continuous load path from the roof to the foundation. The critical damage to buildings in such events typically occurs due to uplift on the roof, resulting in the loss of crucial diaphragm support at the top of the wall. Connections between individual building elements-roof, walls, floors and foundation-are critical to maintaining structural continuity during a high wind event.
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