Maximum bending moment in simply supported beam under offset point load.
Bending moment
$$ M_{B_{p_{max}}} = {{( P \cdot a \cdot b ) \over \left({ a + b }\right)}} $$
Calculate normal stress in simply supported beam due to bending caused by single force.
Bending stress
$$ \sigma_{bend_{p_{max}}} = {10 ^ 3 \cdot {M_{B_{p_{max}}} \over W_{y_{section}}}} $$