A 2nd level floor system of an office block is made up of a

Question

Task: Analysis and Design of Beam

A 2nd level floor system of an office block is made up of a 125 mm thick slab cast monolithically with stiff beams which are spaced L₃ (centre-to-centre) as shown in Figure 1. You are asked to design the beam in Figure 1 (a). In addition to its self-weight, the beam will carry superimposed dead and live loads on the slab strip (refer to Figure 1 (b) shaded area). The beams are supported by 400 mm x 400 mm columns as shown in Figure 1 (c). The density of the reinforced concrete can be taken as 2400 kg/m³.

(i) Determine the minimum required beam dimensions (b and D) in the nearest 25 mm that can safely carry its self-weight and the superimposed dead and live load and which will satisfy the durability and serviceability requirements.

(ii) Develop the bending moment and shear force diagrams using the simplified method in AS3600 (verify and show that the simplified method can be applied for this beam).

(iii) Design the necessary flexural reinforcement required for positive and negative bending along the length of this beam, i.e. exterior support, midspan and interior support.

(iv) Design the necessary shear reinforcement along the length of the beam.

(v) Draw the reinforcement detailing of the beam (include both flexure and shear), with appropriate sections.

(vi) Determine the total long-term deflection and the incremental deflection of the beam in the end span. You may assume Ψ_s = 0.7 and Ψ_l = 0.4. Check whether these deflections are within the limit specified in AS3600.

(a) General layout of the RC slab supported on beams and columns

(b) Sectional view of X-X

(c) Sectional view of Y-Y

Figure 1. Analysis and design of beams

Answer 1

The assignment mainly focuses on the Analysis and Design of Beam; consider the information and provide solution to each. 1) Find out the minimum required beam dimensions (b and D) in the closest 25 mm which can safely carry its self-weight and the superimposed dead and live load and that will please the durability and serviceability necessities. 2) Build up the bending moment and shear force diagrams employing the simplified process in AS3600 (Confirm and show that the simplified technique can be implemented for this beam). 3) Design the essential flexural reinforcement requisite for negative and positive bending all along the length of this beam, that is, exterior support, mid-span and interior support. 4) Design the essential shear reinforcement all along the length of beam. 5) Sketch the reinforcement featuring of the beam, having suitable sections.