On the application of nonlinear analysis in the design and assessment of reinforced concrete structures

• Published in: Computational Modelling of Concrete and Concrete Structures pp. 8 - 21
• Main Authors: Červenka, J., Šmejkal, Filip, Červenka, V., Kurmann, Davide
• Format: Book Chapter
• Language: English
• Published: CRC Press 2022
• Edition: 1
• Subjects: Continuous Beam; Internal Material Length Scale; Reinforced Concrete; Model Uncertainty; Crack Band Model; Safety Formats; Finite Element; Material Model; Nonlinear Analysis; Pushover Analysis; Test Specimen Geometry; Diagonal Shear Crack; SDOF; Model Uncertainty Factor; Shear Reinforcement; Equivalent SDOF System; Fib Model Code; Large Finite Elements; Equivalent Dynamic Model; Partial Safety Factor; Non-linear Analyses; Pushover Curves; Reinforced Concrete Building; Crack Band
• ISBN: 9781032328454; 9781032327242; 1032328452; 1032327243
• DOI: 10.1201/9781003316404-2

after many years of being only an interesting research topic, nonlinear analysis of reinforced concrete structures is becoming a standard engineering tool that is used in the assessment of existing structures as well as in the design of new structures. This development has been significantly supported by the introduction of new safety formats for nonlinear analysis in the fib model code 2010. Currently the new version of the fib model code 2020 is being finalized. In addition, some of the methods proposed in the fib model code are being implemented in the new version of Eurocodes. The paper provides a summary of the most promising proposals of safety formats for the nonlinear analysis together with the crucial and very important issue of addressing the modelling uncertainty. Some critical and still not fully addressed issues related to the crack band model are discussed and demonstrated using examples of recent blind competition results. Two examples are selected and described in more detail to demonstrate the application of nonlinear analysis, global safety formats and uncertainty treatment in engineering practice. It is concluded that nonlinear modelling represents a very useful engineering tool that can provide better understanding in the structural behavior, expected failure modes and that suitable safety formats, consistent treatment of modelling uncertainties and solid engineering guidelines are needed for their application in practice. This chapter provides a summary of the most promising proposals of safety formats for the nonlinear analysis together with the crucial and very important issue of addressing the modelling uncertainty. It demonstrates the application of nonlinear analysis and the global safety formats to two examples from engineering practice. Additional important features of cracked reinforced concrete include the reduction of compressive strength, shear stiffness and shear strength degradation, often referred as a shear retention effect. The design condition in the standard design practice is applied to critical cross-sections and the load effect is obtained by linear analysis. The experimental data base for the calibration of model uncertainty for a particular material model or modelling approach should include results of experiments relevant to the considered resistance model. The nonlinear methods or constitutive models for concrete structures are usually implemented and used as a part of a software tool.