Evaluations of the stiffness and the ductility of reinforced concrete shear walls have been receiving added emphasis due to their importance in connection with the serviceability limit state design for tall buildings and the ductility design for earthquake-resistant building systems. In this thesis an investigation has been conducted into the effects of steel reinforcement and axial loads on flexural stiffness and curvature ductility of reinforced concrete structural walls. An analytical method of analysis is proposed first in this study for the determination of stresses and strains for a given moment-curvature relationship of reinforced concrete sections. The proposed analytical analysis is performed based on the close form integration. It is less approximate and the numerical errors c...[ Read more ]

Evaluations of the stiffness and the ductility of reinforced concrete shear walls have been receiving added emphasis due to their importance in connection with the serviceability limit state design for tall buildings and the ductility design for earthquake-resistant building systems. In this thesis an investigation has been conducted into the effects of steel reinforcement and axial loads on flexural stiffness and curvature ductility of reinforced concrete structural walls. An analytical method of analysis is proposed first in this study for the determination of stresses and strains for a given moment-curvature relationship of reinforced concrete sections. The proposed analytical analysis is performed based on the close form integration. It is less approximate and the numerical errors can then be reduced significantly, comparing to the numerical integration used in the traditional numerical methods for determining the stress and strain of moment-curvature curves.

Theoretical moment-curvature relationships for typical reinforced concrete wall sections with different steel ratios and different axial load levels are derived respectively. A new model is presented to describe the effects of steel reinforcement and axial forces on the stiffness and ductility of the flexural wall sections. It has been shown that the flexural stiffness of the sections can significantly be increased with the increase in reinforcement ratio in the section. Moreover, the curvature ductility of the sections can be decreased with the increase in the axial forces of the cross-sections.

A 3-point plot is then introduced to describe the proposed model. As the flexural stiffness and the curvature ductility can be evaluated from a moment curvature curve, the 3 point plot provides designers a convenient means of understanding the stiffness and ductility behaviour of the flexural structural walls with the effects of steel reinforcement and axial loads. Design formulas for calculating the flexural stiffness and curvature ductility of the structural walls with consideration of different reinforcement ratios and axial load ratios are derived. The formulas provide practising engineers a very simple and efficient means for the analysis of flexural structural walls, particularly in the preliminary design of shear-wall types of tall buildings.

The practical implications of utilising the enhancing effects of steel reinforcement and axial loads on the flexural stiffness and ductility in the design of structural walls are considerable. Economies could be achieved by recognising these enhancing effects. The research provides a basis for the development of more rational analysis and design of reinforced concrete, flexural structural walls.