Shear Failure Behavior Research Articles

저하중용 후설치 세트앵커의 전단파괴거동에 관한 매개변수 연구

Post-installed concrete set anchors are installed after the concrete hardened. These anchors increasing usage in development of construction equipment and flexible construction. The anchor loaded in shearing exhibits various failure modes such as steel failure, concrete failure, concrete pryout, depending on the shear strength of steel, the strength of concrete, edge distance and anchor interval, etc,. In this study, the objective is to investigate the effects of the variations like anchor embedment depth, edge distance and concrete strength on experimental and finite element analysis of shear failure behavior of post-installed concrete set anchor for light load embedded in concrete. The results of embedment depth experiments show that concrete strength has much affection on the shallow embedment depth. Concrete strength has no much affection with anchor interval and edge distance parameter and both experimental results occurred same failure mode. By comparing the experimental results that occurred steel failure mode show that as strong as concrete strength are the displacement results are small.

An application of a cohesive fracture model combining compression, tension and shear in soft rocks

A cohesive fracture model considering tension, compression and shear material behaviour is implemented into the hybrid continuum–discrete element method, i.e. Universal Distinct Element Code (UDEC), to simulate possible multiple fracture in soft rocks. The fracture model considers both elastic and inelastic (decomposed to fracture and plastic) displacements. The norm of the effective inelastic displacement is used to control the fracture behaviour. Three numerical examples, including Mode-I, Mode-II and Mixed-mode tests, are conducted to verify the model and its implementation in UDEC. The model is subsequently applied to simulate uniaxial compression and Brazilian disc tests on soft rocks and the results are compared with experimental results. The results indicate that the cohesive fracture model is capable of realistically simulating the combined tensile, shear and mixed-mode failure behaviour applicable to geomaterials.

Shear Capacity and Failure Behavior of Steel-Reinforced High Ductile Concrete Beams

The shear behavior of six high ductile fiber reinforced concrete (HDC) beams is studied to investigate the influence of shear-span ratio and HDC mechanical property on the improvement of the shear failure mode and shear capacity of short beams. Four steel-reinforced high ductile concrete beams (SHDC) beams with different shear span ratios are tested under concentrated load at midspan. To study the effect of stirrups and steel on the shear capacity of short beams, two additional specimens without steel but one including stirrups are investigated. The main aspects of SHDC beams are discussed in detail, such as failure mode, deformability, and shear capacity. Test results show that the SHDC short beams keep high residual bearing capacity and great integrity when suffering from large deformation. It is revealed that HDC increased the shear ductility and improved the shear failure mode of short beams. A comparison with the shear equations of Chinese YB9082-2006 shows that the Chinese Code equation provides conservative estimation for HDC beams. This study proposes modifications to the equation for predicting the shear capacity of HDC beams.

Shear failure analysis of a shallow depth unsupported borehole drilled through poorly cemented granular rock

Adopting an appropriate failure criterion plays a key role in the borehole stability analysis. In this paper the induced stresses on a vertical borehole wall were calculated based on the elastic theory. Then, to predict the stability of a borehole drilled through a poorly cemented sand formation, failure envelopes in different failure criterion domains were derived using the results from a series of precise laboratory tests conducted on solid and hollow cylinder specimens. The mixture used in specimen preparation was designed to simulate the properties of the samples collected from depths up to 200m at a drilling site in South Australia. The hollow cylinder test apparatus was developed by modifying a Hoek triaxial cell. These modifications allowed observing the process of debonding of sand grains from the borehole wall during the test and consequently, acquiring a better understanding on the failure mechanisms of a borehole drilled through poorly cemented sand formations. Three well-known failure criterion domains; Coulomb, Drucker–Prager and Mogi, were considered versus the laboratory test data to investigate their capability to predict the shear failure of a borehole using the data from hollow cylinder tests. The obtained results showed the significance of selecting an appropriate failure domain for predicting the shear failure behavior of poorly cemented sands near the borehole wall. The results also showed that the Coulomb criterion is not well suited for predicting the borehole failure when there is no pressure acting inside the borehole. A failure envelope based on the Mogi domain was developed which can be used for the far-field stress states. The introduced failure envelope allows predicting the stability of a borehole drilled in poorly cemented sands.

고인성 섬유 시멘트 복합재료를 사용한 RC보의 전단보강효과

This paper presents the results of experimental investigations on the shear failure behaviors of reinforced concrete beams using ductile fiber reinforced cementitious composite (DFRCC). Total 10 RC beams of 150x300x1,000mm size were tested by 4-point bending under the displacement control. The main parameters of the experiment are surface treatment by grinding and preloading to the cracking point in the repair process. The load-displacement curves, diagonal tension cracking load, flexural cracking load, and shear strength were obtained. The test results showed that the DFRCC can be used effectively for restoring the shear strength approximately 99% to the original value under the condition that the appropriate thickness and surface treatment like grinding are assured. For further research, the specimens taken from real deteriorated structures will need to be tested after being repaired with DFRCC.

Interface Properties of Synthetic Rock Specimens: Experimental and Numerical Investigation

Abstract To support the development of centrifuge models to simulate seismic rock slope failures, potential model materials were subjected to direct shear tests to characterize the properties of the interfaces. Three synthetic rock materials were investigated: blocks cast out of a commercially available gypsum cement, blocks cast out of a Nevada sand/gypsum mix, and rock blocks with sandpaper glued to the shear surfaces. The materials were evaluated primarily on the consistency of the measured properties and the observed shear failure behavior. The laboratory direct shear tests were modeled numerically with the software package UDEC to observe how well the numerical results using joint constitutive models available in the software compare to the experimental results. The Coulomb slip joint model predicts the interface behavior well for the gypsum and sand/gypsum materials, which displayed basic elastic-plastic behavior during shear, and the Coulomb slip with residual strength model captured the peak to residual behavior observed in the tests on the sandpaper interfaces. The use of a different joint shear stiffness value for each simulation, corresponding to the measured laboratory value associated with each applied normal stress, clearly contributed to this excellent match; more general models utilizing a constant joint shear stiffness value applied to blocks that are subjected to different normal stresses may not display such close agreement with observed behavior.

Study on Dynamic Shear Resistance of RC Beams

The aim of this study was to investigate the dynamic shear failure behavior of RC beams under rapid loading through an experimental study and also to set up a strut-and-tie model with loading rate effect to predict the dynamic shear resistance of RC beams. Thus, rapid loading test with 24 RC beams with a shear span-to-deep ratio of 1.9 was performed, in which shear reinforcement ratio and loading rate were variable. All of the RC beams exhibited shear compression failure. Although the shear resistance increases with increasing loading rate, the influence of loading rate on the shear resistance clearly depends on shear reinforcement ratio. The strut-and-tie model with loading rate effect was finally developed, in which the thickness of the compression strut was formulated to be increased with an increase in loading rate. The developed strut-and-tie model was good agreement with the experimental results.

The tensile and shear failure behavior dependence on chain length and temperature in amorphous polymers

The tensile and shear failure behavior dependence on chain length and temperature in amorphous polymers are scrutinized using molecular dynamics simulations. A wide range chain length of alkane is tested under tension and shear with various temperatures. We find that the broken rate (the broken bond number to all polymer chain number ratios) under tension and shear increases with increasing chain length and temperature. For a given chain length and temperature, the broken rates under shear are always higher than those under tension at a same large strain. For a given chain length, the tensile and shear stresses decrease with increasing temperature. We propose three typical fracture mechanisms to effectively elucidate the ductile fracture response based on the predominance of chain scission process.

Experimental Study on Shear Failure Behaviors and Wear Resistance of Copper-Electroplated Graphite Compacts

This work examines the processing and some mechanical properties of copper-electroplated graphite compacts. Shear and wear tests were conducted. Natural graphite (NG) flakes were compressed to make graphite compacts. No polymer binder was added in the compact. For reinforcing and preventing the NG particles from peeling off, a copper layer was electroplated on the compact. The density of green graphite compact approached a limit when the forming pressure was higher than 100 MPa. The results indicated that the shear strengths increase 150% and the wear resistance is improved more than ten times because of the copper layer. The induced damage mechanisms were examined, and the influence of the copper layer on the damage is discussed.

도넛형 이방향 중공슬래브 뚫림전단 강도 및 파괴거동에 대한 실험적 연구

This paper presents the punching shear strength and failure behavior of biaxial hollow slab with donut type hollow-shaper. Until now, various types of slab systems which can reduce self-weight of slabs have been studied as the height and width of building structures rapidly increase. A biaxial hollow slab system is widely known as one of the effective slab system which can reduce self-weight of slab. According to previous studies, the biaxial hollow slab has weakness in slab-column connection compared with solid slab. And previous studies pointed out reduced cross-section area of concrete by hollows as the cause. It is assumed in this study that the shape of hollows and the location of hollow-shaper exert influence on the punching shear strength of biaxial hollow slabs. Therefore, donut type hollow-shaper which was suggested as the optimal hollow shape in previous study was used in this study. To verify the punching shear strength and failure behaviour of donut type biaxial hollow slab, punching shear tests were conducted. 4 test specimens were used for test parameters. One was conventional RC slab and 3 were hollow slabs. The test parameter was the area of critical section which were determined by the number of hollow-shaper around the column. The punching shear strength of the donut type biaxial hollow slabs are 87%~103% of solid slabs and superior to generic biaxial hollow slabs. And punching shear cracks occurred at the first perimeter line of donut type hollows.

Experimental and numerical research for the failure behavior of the clinched joint using modified Rousselier model

The ductile fracture of the clinched joint is studied by the experiments and simulations using a modified Rousselier model. Although tension failure has been successfully predicted by the classical Rousselier damage model, its predictive capability on shear failure is seldom discussed. The microstructure of the clinched joint reveals that the ductile fracture occurs in the neck thickness under the shear and tensile force. So this paper is mainly concerned with application of a modified Rousselier damage model developed by the Guo on the description of the failure behavior of the clinched joint. The three experimental specimens were designed in order to calibrate the damage coefficients kω and the initial void volume fraction f0. The material parameters of the modified Rousselier model were identified by an inverse method comparing the experimental results with the numerical results. The modified Rousselier model could capture both tension and shear failure behavior of the clinched joint. The numerical results and the experimental results indicate the Lode parameters in the new damage evolution model can capture the failure behavior and the evolution process during the clinching process.

An Experimental Study on the Shear Failure Behavior of Post-installed Set Anchor for Concrete

최근 콘크리트 구조물의 보수 보강 및 리모델링 시 구조부재를 부착시키거나 고정하는데 있어서 시공의 유연성 및 용이성으로 후설치 앵커의 사용량이 증가하고 있는 실정이다. 전단하중을 받는 앵커는 강재와 콘크리트의 강도, 연단거리, 앵커간격 등에 따라 다양한 파괴모드를 보이며 대표적인 파괴모드는 강재 파괴, 콘크리트 파열 파괴, 콘크리트 프라이 아웃 파괴 등으로 나타난다. 본 연구에서는 매입깊이, 앵커간격, 연단거리 및 콘크리트 강도를 변수로 한 세트앵커의 전단 실험을 통하여 콘크리트에 매입된 후설치 앵커의 전단 파괴거동에 미치는 영향을 규명하는 것을 그 목적으로 한다. 매입깊이 변수의 실험 결과 매입깊이가 얕을수록 콘크리트 강도의 영향이 큰 것으로 나타났다. 앵커간격 변수의 실험 결과 모두 강재 파괴가 발생하였으며, 연단거리 변수의 실험 결과 매입깊이 이하인 경우 모두 콘크리트 파괴가 발생하였다. 동일한 변수의 실험 결과를 비교해 보았을 때 콘크리트 강도가 클수록 변위가 상대적으로 더 작게 나타났다. Recently the use of concrete post-installed set anchors has been increasing because this constructing method is flexible and easy to attach or fix structural members when we repair, reinforce, or remodel a concrete structures. Depending on the shear strength of steel, the strength of concrete, edge distance and anchor interval, etc, the anchor loaded in shearing exhibits various failure modes such as steel failure, concrete failure, concrete pryout. In this study, the objective is to investigate the effects of the variations like anchor embedment depth, anchor interval, edge distance and concrete strength on the shear failure behavior of post-installed concrete set anchor embedded in concrete. The results of embedment depth experiments show that concrete strength has much effection on the shallow embedment depth. Steel failure occur to all results of the anchor interval experiments, but concrete is failed when edge distance experiments that less than the embedment depth. Through the comparision of the same parameters experiments results show that as strong as concrete strength are the displacement results are small.

In-situ SEM mechanical testing of miniature bonded joints

A novel experimental regime is undertaken to investigate the peel and shear failure behaviour of adhesive joints with composite adherends. Identical single-lap joint specimens were manufactured using an aircraft grade carbon fibre composite material with a high strength, high toughness adhesive used to bond the specimens. Peel dominant conditions are produced through a three-point bend test, and shear conditions were achieved using a compressive lap shear test. A brief finite element study was carried out to verify the presence of peel dominant and shear conditions. The experiments were carried out under an SEM beam, allowing a novel in-situ analysis of the tests to be carried out, and has been used to identify damage progression during failure of the bonds. Post failure SEM analysis has been used to identify the wide range of failure processes under peel and shear conditions. Under peel conditions, a range of failure modes are produced, including; adhesive failure, thin layer cohesive failure, fibre tear and light fibre tear failure and importantly, mixed failure. Under shear failure conditions, only interface failure was observed, with cusps being the dominant visible feature on the failure surface.

Influence of Loading Rate on Shear Capacity of Reinforced Concrete Beams

This study aims to investigate the dynamic shear failure behavior of reinforced concrete (RC) beams under rapid loading through an experimental study and set up a strut-and-tie model with loading rate effects to predict the dynamic shear capacity of RC beams. Thus, rapid loading test for 48 RC beams was performed, in which shear span-to-depth ratio, shear reinforcement ratio and loading rate were variable. The RC beams exhibited diagonal tension failure, shear compression failure and flexural failure depending on the shear span-to-depth ratio and the shear reinforcement ratio. The influence of loading rate on the maximum resistance is more significant for the RC beams failed in shear than for those failed in flexure. The strut-and-tie model with loading rate effects was developed, in which the thickness of the compression strut was formulated to be increased with an increase in loading rate. The developed strut-and-tie model was in good agreement with the experimental results.

Shear failure behaviors of a web panel with local corrosion depending on web boundary conditions

In this study, the shear buckling behavior and shear failure mode of a locally corroded web were examined using nonlinear FE analysis, depending on the corroded web and web boundary conditions. Longitudinally corroded web panels and triangularly corroded webs were considered for quantitatively evaluating the shear buckling behaviors of the corroded web panel. For the longitudinally corroded web panels, the shear buckling strengths were only slightly reduced by about 9–16% depending on the corroded web conditions and web boundary conditions. Their diagonal tension field widened and became distorted with the pronounced shear–bent shape of the corroded web. In particular, in a web-flange separated boundary case, it is out-of-plane displacement and deformation exhibited different shear buckling modes, i.e., a diagonal tension field in its upper part and a large triangular lateral displacement in its lower part. On the other hand, the triangularly corroded web panels had only slight effect on the shear buckling resistance of the corroded web because this corroded model does not affect the diagonal tension field of web panel.

Shear behaviour of glued structural fibre composite sandwich beams

The shear behaviour of structural sandwich beams made by gluing together fibre composite sandwich panels in the flatwise and in the edgewise positions was investigated with a view of using this material for construction and building applications. The effect of the number and orientation of sandwich laminations on the shear strength and failure behaviour of glued sandwich beams is examined using an asymmetrical beam shear test. The results showed that the behaviour of the glued sandwich beams in the flatwise position is governed by the shear strength of the core while in the edgewise position by the shear strength of the skin. In the edgewise position, the skin carries almost 60% of the load but only 20% in the flatwise position. With increasing sandwich laminations, the glued sandwich beams in the edgewise position achieved over 200% shear strength than beams in the flatwise position. The presence of vertical fibre composite skins has resulted in a more ductile failure behaviour for beams in the edgewise position. The results of the theoretical and numerical evaluations on the shear strength of the glued sandwich beams using the shear properties of the skin and the core were in good agreement with the experimental results.

Re-defining failure envelopes for silicon carbide composites based on damage process analysis by acoustic emission

A silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composite is a promising candidate for a fusion DEMO blanket. To develop design codes in practical use of them, strength anisotropy is an important issue to be clarified and therefore this study aimed to evaluate the failure behavior of the SiC/SiC composites to provide a strength map. For this purpose, detailed tensile, compressive and in-plane shear failure behaviors were evaluated by the acoustic emission (AE) technique for a plain–weave (P/W) chemically vapor-infiltration (CVI) SiC/SiC composite. The AE results distinguished damage accumulation processes by separately discussing localized variations of power within a time series by wavelet analysis. Of particular emphasis is that matrix cracking occurred prior to the proportional limit stress (PLS) by both tensile and compressive tests. This is because the rough-surface of SiC fibers resulted in the strong frictional stress at the fiber/matrix (F/M) interface, showing linearity in the stress–strain curve beyond the actual matrix cracking stress (i.e., possibly no sliding of the fibers at the F/M interface). In this paper, an updated failure envelope was provided by referring the true matrix cracking stresses as more realistic and reasonable failure criteria.

Shear Failure Behavior of Y-Eccentrically Brace in RC Frame Structures under Earthquake Action

In order to study the mechanical characteristics and the shear failure behavior under earthquake action, a single-storey single-span RC frame structure strengthened with Y-eccentrically brace were designed and manufactured to be 1/3 scale. The pseudo-dynamic testing method was carried out under El-Centro earthquake action with different peak acceleration adjusted by Code for Seismic Design of Buildings in mainland China. The testing result indicates that RC frame structure strengthened with Y-eccentrically steel brace presents perfect seismic performance under strong earthquake action, at one time, the seismic performance maybe affected by the length of outsourcing steel at the joint between energy dissipation element of eccentric steel brace and RC frame beam. The joint should be considerably designed to make sure that shear failure can firstly occur in energy dissipation element.

Experimental characterization of interlaminar shear failure in sandwich structures under three-point bending

We applied an improved six-step phase-shifting method in digital photoelasticity to an adhesively bonded aluminum/epoxy/aluminum sandwich structure in order to study interlaminar shear failure behavior. Before and after three-point bending, a self-balanced thermal residual shear stress appeared on the interface because of the difference in thermal expansion coefficients between aluminum faces and epoxy core interlayer. At the beginning of loading, the shear stress in the core layer distributes continuously and forms shear bands tilting at a 45° direction. It then joins with the upper and bottom aluminum faces in order to realize the shear load transfer. As the bending load increases, the maximum interface shear stress occurs near the supports and a partially debonded region appears at the interface. The interfacial shear stress in the partially debonded region decreases rapidly until a shear failure occurs. A load–flexibility curve of the vibration-damping–type sandwich structure agrees well with the theoretical prediction of a laminated beam.

Comparison of 3D four-directional and five-directional braided SiO2f/SiO2 composites with respect to mechanical properties and fracture behavior

Mechanical properties of three-dimensionally (3D) four-directional and five-directional braided quartz preforms reinforced silica (SiO2f/SiO2) composites were compared. Mechanical properties tests were carried out under various loading conditions, including tensile, flexural and shear loading. The mechanical testing results indicated that the tensile strength, flexural strength and shear strength of the 3D five-directional braided SiO2f/SiO2 composite was superior to that of 3D four-directional braided SiO2f/SiO2 composite; especially the tensile strength (increased by 24 percentage points). Both 3D four-directional and five-directional braided SiO2f/SiO2 composites exhibited graceful failure under loading. Shear failure behavior between these two composites differed entirely, because of the existence of the 5th yarns in 3D five-directional SiO2f/SiO2 composite. The fiber placement in the preform strongly affected the mechanical property and failure behavior of the composite. 3D five-directional braided SiO2f/SiO2 composite had better strength and toughness than 3D four-directional braided SiO2f/SiO2 composite.