Papers by Keyword: Failure Process

Abstract: Arch dam’s failure is a super nonlinear irreversible process. We can find the damage mechanism from research of it and get a more reasonable and perceive safety factor. It analyses overload of the highest RCC arch dam of the world and shows dam’s failure process by water specific gravity overcharge method and water-level overcharge method. It gets overload safety factor from study on arch dam’s failure process and also gives the reason that why different methods get different safey factor.

Abstract: According to the problem of mine water bursting frequent accidents when Mine into the deep mining. Based on the theory of fluid-solid coupling, accounting for the effect on permeability by damage and stress. Analysis of influence factors what hydraulic fracturing process, fracture propagation pattern, and influencing factors including shape and magnitude of inlet hole, stress conditions, and specimen strength were investigated. Hydraulic fracturing is not only a natural action but also an artificial method to alter rock structure. Application of rock failure process analysis software coupled seepage-stress F-RFPA2D, numerical simulated rock water pressure to cause crack rupture instability process, research the fracture law of the rock on water pressure and vertical loading. Combine similar physical experiment model, contrast analysis of two broken results and stress-strain curve, reveals instability mechanical behavior of rock hydraulic fracture process. Obtain deep mining in the process of mine water seepage and water extrude, overburden rock crack up, expand, water seepage, water extrude, instability rupture process rules. numerical simulation results and experimental results has good uniformity, for disaster of the mine water extrude has immeasurable prediction practical.

Abstract: This paper introduces an example on AE monitoring and ultrasonic wave velocity measurement of concrete (C20). Experiment on AE characteristic of the full failure process of concrete is carried out on the pressing machine. AE sensors can be surface mounted. A system (the 8-channels, high-speed acquiring and analyzing AE signal), called HUS (Hyperion Ultrasonic System), was employed to acquire and record AE characteristics. AE signals were recorded during loading (fracture propagation) subject to the uniaxial compressive loading until failure. Using a simplex location algorithm allows AE event location from first arrival times to be determined by the AE sensors. The mechanical properties of concrete and acoustic emission characteristic, including the full stress-strain curves, AE counts, and AE rate and ultrasonic wave velocity, were obtained. The relations among AE counts, AE rate, stress levels, ultrasonic wave velocity and time are analyzed in detail. This paper reports AE observations made with an array of this new high-fidelity. Crack initiation and crack propagation due to the uniaxial compressive loading were monitored for AE activity and compared with visual observation. Meanwhile, stress changing influence the wave velocity of concrete; with the initial crack expands, up to the rock sample failure, the wave velocity falls gradually. Some insight into the percentage of AE events that must actually be detected to describe the health of concrete sample was gained.

Abstract: In this paper, the bond length effect of FRP plate on bonding performance and the distribution patterns of the stress in FRP plate was investigated using 3D Realistic Failure Process Analysis (RFPA^3D) code to study the debonding mechanism of the FRP plate bonded to concrete block. Numerical simulations show that the progressive debonding of FRP plate bonded to concrete occurs in the concrete on the condition of different bond lengths can be divided into four stages: elastic-deformation stage, elastic-softening stage, elastic-softening-debonding stage and softening-debonding stage. It is also show that the interfacial bond strength and the global slip of FRP-to-concrete increase with the increase of the bond length.

Abstract: The impacting action of flood destroyed dramatically the rural buildings. In this paper, the rural building was analyzed numerically to investigate the destruction of rural building due to the flood impact. The rural building was discretized into 7950 8-node block elements and 4098 Goodman elements to simulate the brick and mortar respectively. The rule impact loading of flood on rural building was calculated using the criterion of gravity similarity according to test results. Finally, the stress, the displacement and the failure process of the rural building are studied. Firstly, the mortar element locates on the wall between the door and the window failure and more and more mortar and brick elements failure with the increasing loading. Finally, the right wall was damaged because the door and the right window decreased its stiffness. Because the failure mortar and brick elements decrease the stiffness of the structure, the displacements of the rural building increased nonlinearly with the increasing loading.

Abstract: To investigate failure mechanism and toughening features of fiber reinforced concrete (FRC) with different reinforced fibers, meso-level numerical simulations have been conducted on FRCs incorporated with steel, glass and polypropylene fibers, respectively (which were named as SFRC, PPRC and GRC). The complete failure process of crack initiation, coalescence and development, interaction and final break have been simulated. By analyzing the failure patterns of specimens, also the spatial and temporal distribution of acoustic emission and loading - step curves, it can be concluded that both peak strength and toughness of SFRC and GRC can be greatly improved. However, for PRC, the improvement of peak strength is little while its toughness can be enhanced significantly.

Abstract: Realistic Failure Process Analysis (RFPA3D) was used to simulate the concrete-filled rectangular steel tube columns which are subjected to axial loads. The ultimate bearing capacity and the load-strain figures were presented. The Numerical simulation results were verified by experimental data of the paper [5]. Meanwhile, the development process of crack in the specimen was described. The whole failure process of rectangular steel tube columns was reproduced. The failure principles of concrete-filled rectangular steel tube column were discussed deeply.

Abstract: Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Fitness considerations for long-life implementation of aerospace composites include understanding phenomena such as fatigue, creep and stress corrosion cracking that affect reliability, life expectancy, and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined; furthermore, SI takes into account service duty.

Abstract: As the implementations of the western development in China, more and more tunnels will get through the western mountains in China. In order to economize the construction costs, a new type of underground structural form called branching-out tunnel must be applied. The failure process of the branching-out tunnel under lateral overload action is also greatly complicated, which is related with the depth of the mountains, the branching-out angle, the in-situ stress field, the thickness of the middle wall and so on. This paper uses the 3D-physical model of geo-mechanical model tests to study the stability and failure process of this complicated structure, especially the part of the middle wall. The physical model is built up in a new kind of analogy material. In the process of the whole experiments, different lateral pressures imposed on both of the lateral planes of the physical model. According to different lateral pressures, we have attained the change of the stress and displacement field and looked into the failure process of the pivotal positions in the branching-out tunnel. We also use finite element method analysis software RFPA (Realistic Failure Process Analysis) to simulate the whole failure process of the branching-out tunnel. Finally, we have got the load-bearing safety reliability of this complicated structure through comparative analysis of physical modeling and numerical simulation.

Abstract: A numerical method from the mesoscopic point of view is proposed to describe the fracture process of concrete. At mesoscopic level, concrete is considered as a three-phase composite consisting of mortar matrix, coarse aggregate and interfacial transition zone (ITZ) between them. According to the grading of coarse aggregate obtained from sieve analysis, the random aggregate models with polygonal aggregates were generated by Monte Carlo random sampling principle. In this work, the tensile cracking is assumed to the only failure criterion at the mesoscopic scale; and the stress-separation law based on the fictitious crack model is adopted to allay the sensitivity on mesh size in the softening regime. The nonlinear finite element method is used in the simulation of concrete under bend loading. The influence of the shape of aggregate on the macroscopic response of concrete is also investigated. Numerical results show that the strength of the specimen with circular aggregate is higher than the specimen with arbitrary polygonal aggregate. The predicted bending strength agrees well with experimental data.