Strength reduction design method for reinforced concrete structures: Generalization

• Published in: Engineering structures 2022-05, Vol.258, p.114134, Article 114134
• Main Authors: Abra, Oumaima, Ben Ftima, Mahdi
• Format: Article
• Language: English
• Subjects: 3D stresses; Calibration; Computer applications; Concrete; Concrete piles; Concrete structures; Configurations; Design; Design parameters; Design standards; Design techniques; Failure mechanisms; Incompatibility; Lower bounds; Non-linear finite elements; Pile caps; Reduction; Reinforced concrete; Stiffening; Strain incompatibility; Strength reduction method; Structural members; Strut-and-tie method; Struts; Tension stiffening; Validation
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2022.114134

•An enhanced 3D strength reduction design approach is developed for reinforced concrete.•It is suitable for computer-aided design of complex reinforced concrete structures.•A new generalized calibration procedure to consider incompatibility is presented.•Important conclusions on the strain incompatibility and shape of nodal zones in 3D.•V&V examples demonstrate that the method provides lower bound solutions. This work presents a generalization and enhancement of a previously developed computational strength reduction design method (SRDM) for the design of complex reinforced concrete structures. The enhanced method SRDM-3D presented in this work extends the applicability of the original method to a more general 3D state of stresses and to different possible input tension stiffening and incompatibility laws, via a new calibration procedure. It also addresses the limitations of the strut-and-tie method initially developed and often applied to 2D geometries. Application of the developed method for simple 3D configurations allowed to obtain important results regarding the shape of nodal zones, incompatibility between concrete struts and reinforcement ties and conditions for the development of bottle-shaped struts for the general 3D framework of reinforced concrete structural elements. Validation examples presented at the end of the study on reinforced concrete pile caps demonstrate the robustness of the developed method, and its ability to provide a safe lower-bound design solution to different geometry configurations and different failure mechanisms. The developed method has the advantage of using a simple constitutive law and input parameters that are standard parameters required for design of RC structures.