Concrete, being the most widely used construction material, contributes substantially to global greenhouse gas emissions. To reduce the environmental impact of concrete structures, researchers have explored both material enhancement and structural optimisation. This study focuses on structural optimisation of reinforced concrete (RC) beams through topology optimisation (TO), a technique that efficiently arranges material within a given design domain. The proposed TO approach involves inclining stirrup reinforcements and introducing triangular voids that align with the stirrup angles, creating truss-like configurations within RC beams. Three such configurations, offering potential concrete volume reductions of 23–26%, are selected. Numerical analysis, considering the non-linear behavior of reinforced concrete is performed on six RC beams- three voided beams with truss configurations and three corresponding solid beams using Finite Element Analysis (FEA) software ABAQUS. All FEA results are compared against a solid RC benchmark beam designed per Eurocode 2 guidelines. Additionally, a parametric study investigates the effect of varying stirrup diameters. The findings lay the groundwork for advancing TO strategies in RC horizontal elements, even when using conventional materials such as 35 MPa concrete and 550 MPa yield strength steel. This research also envisions the development of an automated, resource-efficient design and manufacturing process, supported by a reusable automated shuttering system suitable for engineering firms and automated precast concrete production plants.