Modified compression field theory and disturbed stress field model on the simulation of the global and local behaviour of non-planar reinforced concrete walls under cyclic and dynamic loading

Hoult, Ryan [UCL] Saraiva Esteves Pacheco De Almeida, João [UCL]

The Modified Compression Field Theory (MCFT) offers an improved understanding of concrete behaviour by considering it as an orthotropic material and incorporating com-prehensive rotating, smeared crack models. Despite its widespread applicability and reliability, shortcomings have been identified, particularly in scenarios involving substantial reinforcement, high biaxial compressive loads, and minimal transverse reinforcement. The introduction of the Disturbed Stress Field Model (DSFM), an extension of MCFT, ad-dresses some of these limitations by incorporating discrete slip on crack surfaces, thus refining the alignment between principal stress and strain fields. This paper explores the implementation and suitability of MCFT and DSFM within the VecTor suite of finite element software for simulating the response of non-planar RC U-shaped core walls in quasi-static and dynamic tests. Blind prediction and postdiction analyses underscore the significance of modelling assumptions and emphasize the necessity of certain modelling approaches. Reducing the fourth mode Rayleigh damping from 10 to 2% significantly improved the simulated pre-yield displacement time-histories. Introducing strain penetration effects into the model enhanced local behaviour. For GM5, the maximum measured tensile base strain was 5.7%, compared to the simulated 5.3%. Peak displacements for the largest unidirectional ground motion were significantly underestimated at -79 mm compared to the measured -116 mm. Factors like base shear sliding likely contributed to the peak displacements, which the current model could not simulate. The study underscores the importance of MCFT/DSFM in accurately capturing structural behaviour and offers insights for future modelling endeavours in complex RC structures.