How to decide the reinforcement rods for a beam of span 30' Dimension of the room is 20'x30' and the beam is coming at the centre of rcc roof. Basement is load bearing stone masonry and walls are 9?

To determine the reinforcement rods for a 30-foot span beam, you should first calculate the loads acting on the beam, including both dead loads (weight of the roof, walls, and any additional fixtures) and live loads (occupancy, furniture, etc.). Use structural analysis methods to assess bending moments and shear forces, which are critical for sizing the reinforcement. Typically, a structural engineer would then specify the number and diameter of reinforcement bars (rebar) based on these calculations, ensuring that they meet the requirements for both strength and serviceability. Additionally, consider local building codes and safety factors in your design.