CEMENT & CONCRETE COMPOSITES (Elsevier)
Bond behavior evaluation of deformed rebar dependent on lateral pressure confinement including various structural parameters
Farooq, U; Nakamura, H; Miura, T
CEMENT & CONCRETE COMPOSITES, Vol.119, 2021, MAY.
(https://doi.org/10.1016/j.cemconcomp.2021.103996)
Abstract
An analytical method based on Three-Dimensional Rigid Body Spring Model (3D RBSM) was proposed to evaluate the bond behavior of deformed rebar in RC structures dependent on lateral pressure confinement conditions. The method used voronoi mesh and beam element to model concrete and reinforcement respectively that was previously proposed by authors to simulate split failure only. In this study, applicability was extended to evaluate transition from split to pullout failure by extending proposed local bond model. It was confirmed that this simple beam element-based model can reproduce experimentally observed bond behavior dependent on various lateral pressure levels and frictional conditions. Most importantly, method can evaluate the internal cracking and stress distribution governed failure mechanisms dependent on confinement conditions. Meanwhile, in comparison to FEM and RBSM based models with 3D formation of rebar with rib, the proposed model is an efficient and economical alternative to evaluate confinement effects in RC members.
Mesoscale simulation of pull-out performance for corroded reinforcement with stirrup confinement in concrete by 3D RBSM
Avadh, K; Jiradilok, P; Bolander, JE; Nagai, K
CEMENT & CONCRETE COMPOSITES, Vol.116, 2021, FEB.
(https://doi.org/10.1016/j.cemconcomp.2020.103895)
Abstract
The confining effect of concrete cover and stirrups reduces the rate of bond deterioration due to corrosion. However, the large dispersion in recorded experimental data makes it difficult to clearly separate the influence of cover depth and stirrup confinement on bond degradation. This study utilises the discrete 3D Rigid Body Spring Model (RBSM) to conduct a meso-scale investigation regarding the effect of cover thickness and stirrup confinement on internal crack evolution and pull-out behaviour in corroded reinforced concrete models. The simulation scheme is divided into two stages. In stage 1, different degrees of corrosion are introduced, producing cracking in the cover concrete; in stage 2, the corroded main reinforcement is pulled out from the damaged concrete. 3D RBSM is advantageous because the concrete is randomly meshed to reduce mesh bias on crack propagation and the actual geometry of the deformed bars is modelled. The simulation results clarify that the presence of thicker cover delays crack initiation but increases the rate of crack opening. Stirrups do not have any significant effect on crack initiation but effectively restrict crack growth. An investigation of the internal stress in the simulation models shows that tensile stresses generated in stirrups during corrosion are responsible for reactionary confining pressure that restricts crack propagation. Load-displacement curves show reductions in pull-out capacity, stiffness and ductility with increasing corrosion damage. The relative influence of crack opening and stirrup volume on the rate of bond degradation with respect to average surface crack width are discussed and compared with published experimental results and an empirical equation.