Civil MDC



When designing a prestressed concrete section, it is important to check the shear capacity to ensure that the section can withstand the applied shear forces. Here are the general steps for checking shear in a rectangular prestressed concrete section:

  1. Determine the Design Shear Force: Calculate or obtain the design shear force acting on the section. This can be done by analyzing the loads and forces acting on the structure.
  2. Calculate the Shear Capacity: The shear capacity of a prestressed concrete section is determined by the contribution of both the concrete and the shear reinforcement. The calculation methods can vary depending on the design code being used. The most common methods are the truss analogy method and the strut-and-tie method.
  3. Concrete Shear Capacity: Calculate the concrete shear capacity of the section. This is based on the shear strength of the concrete, taking into account factors such as the concrete strength, aggregate type and size, and the section’s geometry. Design codes provide formulas or charts for determining the concrete shear capacity.
  4. Shear Reinforcement: Determine the shear reinforcement required to enhance the shear capacity of the section. The amount and arrangement of shear reinforcement depend on the design shear force, concrete shear capacity, and specific design code provisions.
  5. Shear Reinforcement Check: Calculate the contribution of the shear reinforcement to the shear capacity of the section. This involves determining the shear resistance provided by the shear reinforcement and comparing it to the design shear force. The calculation methods depend on the type of shear reinforcement used (e.g., stirrups, bent-up bars).
  6. Check Shear Capacity: Compare the design shear force to the total shear capacity, which is the sum of the concrete shear capacity and the contribution from the shear reinforcement. The total shear capacity should be greater than or equal to the design shear force.
  7. Modify the Design if Needed: If the shear capacity is not sufficient to resist the design shear force, adjustments may be necessary. This could include increasing the amount of shear reinforcement, increasing the depth or width of the section, or revising the prestressing tendons layout.

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