1.1 Components: Single Tees 8’-0” wide
Single Tee Many existing buildings utilize single tees, however as precast technologies have improved, manufacturers have realized that double tees are easier to produce, easier to transport because additional bracing is not necessary to hold them up, and the same distance can be spanned, with a shallower depth of the member. In fact, in the newest versions of the PCI Handbook, single tees are not included.
depth (in.)
INTRODUCTION
Design
36”
MANUFACTURE
DESIGN
1
Spans and Service Loads
TRANSPORTX+XASSEMBLY
In the diagrams to the right and on the opposite page, varying depths correspond to span lengths and capacity to support certain levels of service load. The deeper the single tee component, the higher the constructible span. In the lower diagram, each polyline boundary designates the possible safe service loads, depending on depth of the single tee, and the span. Typically, the longer the span, the lower amount of service load the member is able to support. Additionally, the higher the number of reinforcement steel bars used in the precast member, the higher the capability to hold a higher service load. These reinforcement bars also allow the single tees to span farther distances, but as a result of the spans being greater, less service load can be supported.
Increasing Safe Service Loads PLEASE NOTE: The load chart on the opposite page represents a double tee with no additional topping. By adding either a 2 inch or 4 inch topping of reinforced concrete, the span and safe service loads can greatly increase. This is more commonly used when a member needs to be able to support a certain amount of service load, but it cannot increase its span. The amount depth at which the component increases is very small, so this is a more viable option than producing a piece of much greater depth and span. For measurements of safe serviceable loads when using additional topping, please reference the PCI handbook.