<p>This paper presents a simplified displacement-controlled numerical analysis program, capable of tracing the nonlinear load-deflection behaviour of reinforced concrete (RC) beam-slabs using the grillage idealization, subjected to transverse loading. The program includes material nonlinearity by making use of a prescribed moment-curvature relationship, and the elemental stiffness matrix is updated iteratively at each deflection step. The moment-curvature relationship is first validated using experiments reported in the literature. The nonlinear numerical analysis program is validated using recent tests on RC beam-slab systems reported in literature. It is demonstrated that, with minimal input, the program accurately predicts the RC beam-slabs' load-deflection response with the experimental data. To estimate the load transmitted to the edge beams of RC beam-slabs, a parametric study is conducted by varying the governing parameters, such as beam strength and stiffness, across different aspect ratios of the slab. This paper establishes the need to introduce an additional correction factor to the yield line analysis when estimating the load transferred to the deflecting beams supporting a slab. It is found that, for a practical range of aspect ratio, the load transmitted to the short beam is usually underestimated using the yield line analysis. Further, it is also found that the load transmitted to the short beam is higher when the beams are shallow.</p>