Design Data

Code

Design of Concrete Structures (CSA A23.3-19)

References

• Reinforced Concrete Mechanics and Design, 8^th Edition, 2021, James Wight, Pearson, Example 11-5

• Notes on ACI 318-11 Building Code Requirements for Structural Concrete, Twelfth Edition, 2013 Portland Cement Association

• spColumn Engineering Software Program Manual v10.10, STRUCTUREPOINT, 2023

• “Interaction Diagram - Tied Reinforced Concrete Column (Using CSA A23.3-14)” Design Example, STRUCTUREPOINT, 2017

• “Biaxial Bending Interaction Diagrams for Square Reinforced Concrete Column Design (ACI 318-19)” Design Example, STRUCTUREPOINT, 2022

• “Biaxial Bending Interaction Diagrams for Rectangular Reinforced Concrete Column Design (ACI 318-19)” Design Example, STRUCTUREPOINT, 2022

• “Biaxial Bending Interaction Diagrams for C-Shaped Concrete Core Wall Design (ACI 318-19)” Design Example, STRUCTUREPOINT, 2022

• “Biaxial Bending Interaction Diagrams for Spiral Reinforced Circular Concrete Column Design (ACI 318-19)” Design Example, STRUCTUREPOINT, 2022

• “Manual Design Procedure for Columns and Walls with Biaxial Bending (ACI 318-11-14-19)” Design Example, STRUCTUREPOINT, 2022

Design Data

f_c’ = 27.5 MPa

f_y = 400 MPa

Cover = 60 mm to bar center of the reinforcement

Column dimensions and reinforcement locations are shown in following figure.

Figure 2 - Reinforced Concrete Column Cross-Section and Reinforcement Locations

Solution

In a reinforced concrete column, the determination of the axial load resistance, P_r, and the biaxial moment resistance, M_rx and M_ry, involves a trial-and-error process for calculating the neutral axis depth and angle α. The neutral axis depth and angle are provided as an input (The neutral axis position crosses the vertical axis of symmetry of the section at 242.24 mm leading to c = 309.78 mm and an angle of α = 30.0º) for illustration.

The steps to calculate biaxial flexural strength of a reinforced concrete column for a given nominal axial strength and moment ratio of biaxial bending moments is discussed in details in “Biaxial Bending Interaction Diagrams for Rectangular Reinforced Concrete Column Design (ACI 318-19)” design example.

Figure 3 - Axial Load Resistance and Biaxial Moment Resistance Calculation Methods for a Reinforced Concrete Column