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Figure 6.23. Results of tests on simply supported beams without shear reinforcement subjected to distributed loads

6.2.2.4. Prestressed members without shear reinforcement

Four failure modes may be envisaged under combination of shear and bending within the extremity region for such elements:

1. Exceeding the tensile strength of concrete in regions uncracked in bending as described by expression (6.4).

2. Exceeding the shear resistance given by expression (6.2a) in presence of bending moments greater than the cracking bending moment.

3. Anchorage loss due to bending cracks within transmission length.

4. Snap back failure at cracking bending moment outside the transmission length, when the acting shear corresponding to the cracking bending moment exceeds the bearing capacity calculated with expression (6.2a).

The designer should verify all the four failure mechanisms described above with particular care to the snap back behavior.

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