Loadbearing facade units become part of the structure rather than having the structure support them. Perimeter columns are eliminated. This is a very efficient use of the high-strength concrete which is used for conventional precast cladding.
Basic design principles for loadbearing wall units are shown in FIGURE 1. Loadbearing units may have a window or other opening incorporated into them.
FIGURE 1 Design Principles for Loadbearing Facades
The location of vertical and horizontal joints is important. The doughnut configuration with the window enclosed in the panel is best. If another configuration must be used then weatherproofing of the facade needs to be carefully thought out, see FIGURE 2.
FIGURE 2 Location of Joints
It is best to use drained and vented joints with loadbearing facades - especially for high-rise structures. FIGURE 3 shows typical details.
Figure 3 Open-Drained Joint Details
Vertical loadbearing connections should be made panel-to-panel as illustrated in FIGURE 4. Connections are detailed to provide for ease of erection and grouting. Issues not resolved on the consultants? drawings will be dealt with by Hanson during the shop drawing process .
FIGURE 4 Typical Connection Details for Loadbearing Facades
As with all precast concrete the design should produce the most commercially attractive result consistent with the architectural and other customer requirements. Panel sizes should be maximised within the limits of transport, crane capacity and temporary support arrangements. Window openings can often be glazed, or at least have the frames installed, before the panels leave Hanson's factory.
Careful detailing and selection of surface finishes will minimise the effects of weathering.
Consult Hanson early in the design process.