Mouse ears or curtains on brickwork jointing. These are the small projections which occur when the horizontal and vertical joints intersect A good bricklayer is constantly observant, looking for flaws in the bricks he or she is laying and discarding materials that may affect the quality of finish. Brickwork can be knocked and nudged by other workers nearby, so check the work frequently to maintain plumb and level. Be critical of your own work and aim to constantly improve your own standards, and employers and customers will always be happy to give you work. As previously mentioned, one-brick walling is brickwork built to produce walling with a width of 215mm the length of one brick. This means that bricks can be laid across the wall as well as in line with the wall. The bricks laid across the wall are called headers, and the bricks in line with the wall are called stretchers, because of the relevant faces of the brick showing in the finished wall. The half-round joint is also commonly referred to as a bucket handle joint. This is because the shaped handle found on old metal buckets was used to form joints in the past.

The simplest building system consists of only two components. One component is a floor, a flat, horizontal surface on which human activities can take place. The FIGURE 1.1 Vertical section through a one-story building with basement shows location of some major components. (Reprinted with permission from F. S. Merritt and J. Ambrose, Building Engineering and Systems Design, 2d ed., Van Nostrand Reinhold, New York.) other component is an enclosure that extends over the floor and generally also around it to provide shelter from the weather for human activities. The ground may serve as the floor in primitive buildings. In better buildings, however, the floor may be a structural deck laid on the ground or supported above ground on structural members, such as the joist and walls in Fig. 1.1. Use of a deck and structural members adds at least two different types of components, or two subsystems, to the simplest building system. Also, often, the enclosure over the floor requires supports, such as the rafter and walls in Fig. 1.1, and the walls, in turn, are seated on foundations in the ground. Additionally, footings are required at the base of the foundations to spread the load over a large area of the ground, to prevent the building from sinking (Fig. 1.2a). Consequently, even slight improvements in a primitive building introduce numerous additional components, or subsystems,

moisture conditions* T  100
F 100
F  T  125
F 125
F  T  150
F Dry 1.0 0.8 0.7 Wet 1.0 0.7 0.5 *Wet and dry service conditions are defined in a Table 10.29 footnote. 1. Two or more split-ring or shear-plate connectors aligned with the direction of the load. 2. Two or more bolts with the same diameter, loaded in shear, and aligned with the direction of the load. 3. Two or more lag screws of the same type and size loaded in single shear and aligned with the direction of the load. When fasteners in adjacent rows are staggered but close together, they may have to be treated as a single row in determination of Cg. This occurs when the distance between adjacent rows is less than one-fourth of the spacing between the closest fasteners in adjacent rows. The group-action factor is necessary because of the following characteristics of a joint with more than two fasteners in a row: The two end fasteners carry a larger load than the interior fasteners. With six or more fasteners in a row, the two end fasteners may carry more than 50% of the load. With bolts, a small redistribution of load from the end bolts to the interior bolts occurs due to crushing of the wood at the end bolts. If failure is in shear, a partial failure occurs before substantial redistribution of load takes place. 10.14.5 Geometry Factor The NDS specifies minimum edge distance, end distance, and spacing required for full design value for bolts, lag screws, and split-ring and shear-plate connectors. The NDS also tabulates nominal design values for these fasteners based on the minimum distances. When the end distance or the spacing is less than the minimum required for full design value but larger than the minimum required for reduced design value, nominal design values should be multiplied by the smallest applicable geometry factor C determined from the end distance and spacing requirements for the type of connector specified. The smallest geometry factor for any connector in a group should be applied to all in the group. For multiple shear connections or for asymmetric three-member connections, the smallest geometry factor for any shear plane should be applied to all fasteners in the connection. The NDS also outlines geometry factors for timber rivet connections loaded perpendicular to grain. 10.14.6 Penetration-Depth Factor Nominal lateral design values for lag screws, wood screws, nails, and spikes are based on a specific penetration into the main member, as established by the shank TABLE 10.31 Group-Action Factors (a) For bolt or lag-screw connections with wood side members*