27.1 General
A corbel is a short cantilever projection which supports a load bearing member and where,
a) the distance between the line of the reaction to the supported load and the root of the corbel
PART 6 STRUCTURAL DESIGN — SECTION 5 CONCRETE: 5A PLAIN AND REINFORCED CONCRETE
is less than (the effective depth of the root of the corbel); and
b) the depth at the outer edge of the contact area of the supported load is not less than one-half of the depth at the root of the corbel.
The depth of the corbel at the face of the support is determined in accordance with 39.5.1.
27.2 Design
27.2.1 Simplifying Assumptions
The concrete and reinforcement may be assumed to act as elements of a simple strut-and-tie system, with the following guidelines:
a) The magnitude of the resistance provided to horizontal force should be not less than one-half of the design vertical load on the corbel (see also 27.2.4).
b) Compatibility of strains between the strut-and-tie at the corbel root should be ensured.
It should be noted that the horizontal link requirement described in 27.2.3 will ensure satisfactory serviceability performance.
27.2.2 Reinforcement Anchorage
At the front face of the corbel, the reinforcement should be anchored either by:
a) Welding to a transverse bar of equal strength — In this case the bearing area of the load should stop short of the face of the support by a distance equal to the cover of the tie reinforcement, or
b) Bending back the bars to form a loop — In this case the bearing area of the load should not project beyond the straight portion of the bars forming the main tension reinforcement.
27.2.3 Shear Reinforcement
Shear reinforcement should be provided in the form of horizontal links distributed in the upper two-third of the effective depth of root of the corbel; this reinforcement should be not less than one-half of the area of the main tension reinforcement and should be adequately anchored.
27.2.4 Resistance to Applied Horizontal Force
Additional reinforcement connected to the supported member should be provided to transmit this force in its entirety.