Analysis of Compression Failure of Concrete by Three Dimensional Rigid Body Spring Model

Yamamoto

et al. 2017

ACT

Self Cite

In order to investigate the influence of crack through section, which is often generated under cyclic loading, on the shear behavior and strength of RC beam, an experimental method was attempted to introduce a 0.5 mm and 1.0 mm-wide pre-crack, respectively, in beam cross section. The two pre-cracked beams were tested and the shear behaviors were compared with a non-cracked one. As the experimental result, it was found that the section pre-cracks led to a significant degradation of shear strength. Secondly, the different shear behaviors between pre-cracked and non-cracked beams were simulated by 3-D RBSM, and the developments of shear resistances were decomposed into the shear contributions provided by beam action and arch action. Based on the decomposition result, it became clear that the arch actions governed the grades of shear strengths and the section pre-cracks played a primary role in inducing extra crack behaviors and obstructing the longitudinal compressive stress transfer in concrete.

Section: Numerical Methods and Modelmentioning

confidence: 99%

“…Moreover, beam elements are attached to concrete elements by zero-size link elements, which can provide a load-transfer mechanism between concrete polyhedron and beam element. The parameters and constitutive models applied in 3-D RBSM have been proposed in the work by Yamamoto et al (2008Yamamoto et al ( , 2014.…”

Section: Numerical Methods and Modelmentioning

confidence: 99%

Investigation of Influence of Section Pre-crack on Shear Strength and Shear Resistance Mechanism of RC Beams by Experiment and 3-D RBSM Analysis

Yamamoto

et al. 2017

ACT

Self Cite

“…Moreover, 3-D RBSM can also be used to investigate the stress-transfer mechanism at the meso levels (Yamamoto et al 2008, Yamamoto 2010. Furthermore, it is applicable to the simulation of uniaxial tension, uniaxial compression, localized compressive failure as well as 3-D effects, the triaxial stress state, dilatancy and confinement effect, which have been investigated in several studies (Yamamoto 2010, Gedik et al 2010.…”

Section: Experimental and Analytical Resultsmentioning

confidence: 99%

“…One normal and two tangential springs are defined at the integral point, which represents the center of the triangles. The effect of bending and torsional moment can be automatically evaluated in this model without setting any rotational springs since a rotation can be calculated by using the coordinates of two integral points (Yamamoto et al 2008, Yamamoto 2010.…”

Section: -D Rbsmmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Stirrups on the Shear Failure Mechanism of Deep Beams

Gedik

Yamamoto

et al. 2012

ACT

Self Cite

The purpose of this study is to clarify the effect of stirrups in deep beams by investigating the shear failure mechanism analytically by using the 3-D Rigid-Body-Spring Model analytical tool. The investigation of the analytical results of the internal stress state and 3-D deformations of deep beams were the key objectives of this study. Firstly, the applicability of the analytical tool on deep beams was confirmed by comparison of analytical and experimental results. Then, the stirrup contribution to load carrying capacity of deep beams was investigated and the shear failure mechanism based on the B and D region concept was clarified analytically. To achieve this, analytical results such as stress distribution, 3-D deformations, crack patterns and strain of stirrups were investigated. Three types of stirrup effect were observed in deep beams. In the a/d= 0.5 case, the peak load increase due to the confinement effect of stirrups. In the a/d=1.0 case, the stirrup contributes to the strut action that leads to an increase in load. In the case of a/d < 1.0, the D region is dominant. On the other hand, the peak load increases significantly with increases of stirrup ratio in the case of a/d > 1.5, in which the truss analogy is dominant rather than the strut action.

Mechanism of shear strength degradation of a reinforced concrete column subjected to cyclic loading

Furuhashi

et al. 2017

Structural Concrete

Self Cite

The purpose of this study was to investigate the mechanism of shear strength degradation of a reinforced concrete (RC) member under cyclic loading. First, the shear failure after flexural yield of tension reinforcing bars of a RC column designed as bridge pier under cyclic loading was simulated by the method of three-dimensional rigid-body-spring-model (3D RBSM) and the shear strength degradation was quantitatively evaluated by a numerical approach. Afterward, based on the shear resistant mechanism, the degraded shear strengths after each load cycle were decoupled into the contributions provided by beam action and arch action, with the use of the numerical local stress results. As the important finding, the mechanism of shear strength degradation due to cyclic loading of the RC column was concluded as with the increase of deformation level, the arch action first degraded gradually whereas the beam action maintained its original capacity; then after losing most capacity of the arch action, the beam action began to decrease rapidly, which caused the shear failure. K E Y W O R D Sarch action, beam action, cyclic loading, RC column, shear strength degradation | INTRODUCTIONIn the seismic design of a reinforced concrete (RC) member, one of the basic requirements is that brittle shear failure is prevented and the shear strength exceeds the shear demand corresponding to the flexural strength. 1-3Although a well-designed RC member under monotonic loading ordinarily suffers flexural failure and shows good deformation performance, if subjected to cyclic loading, the load-bearing capacity often decreases within a relatively small displacement ductility after the flexural yield of the tension reinforcing bars and ultimately shear failure occurs (called shear failure after flexural yield in this study). Because the deformation ability of a RC member under cyclic loading is significant in seismic deformationbased design, many researchers have investigated the influences of several factors such as web reinforcement ratio, tension reinforcement ratio, axial load, and shear span-to-depth ratio for the ultimate deformation ductility of RC members by numerical and experimental methods. [4][5][6][7][8] As shown in Figure 1, the reason for shear failure after the flexural yield of a RC member has been conceptually explained as that the shear strength degrades gradually with the increase of displacement level and ultimately becomes less than the shear demand corresponding to the flexural strength, which leads to a decrease of loadbearing capacity. Corresponding to this failure mode, the relationship between degraded shear strength and displacement ductility (also called the shear capacity degradation curve) was proposed for the first time by the ATC seismic design guidelines. 9