Steel Slab Base Plates – Permissible bending stress (Pbet) selection for base plate bending under column load.

Introduction:
Base plates under steel columns act as short cantilevers between the column footprint and the compression on concrete. The plate is designed in bending, so we must select the correct permissible bending stress for the steel plate material.

Given Data / Assumptions:

• Mild steel or equivalent structural steel base plate.
• Permissible stresses expressed in kg/cm2 per traditional working-stress design.
• Concrete bearing pressure is treated separately.

Concept / Approach:

In working-stress design, the permissible bending stress for mild steel plates is typically taken around two-thirds of the yield stress. For fy ≈ 2500 kg/cm2 (≈ 250 MPa), 0.66 * 2500 ≈ 1650 kg/cm2, which is commonly used for base plate bending checks.

Step-by-Step Solution:

Verification / Alternative check:

Cross-check against codal tables for base plate design examples; values align with standard practice for mild steel under bending in working-stress format.

Why Other Options Are Wrong:

1500 kg/cm2 is conservative but not the common permissible; 1800 and 1890 kg/cm2 are higher than typical WSD value; 2100 kg/cm2 is overly high.

Common Pitfalls:

Confusing steel bending stress with concrete bearing stress, or mixing limit-state and working-stress numbers.

Final Answer:

1650 kg/cm2