Papers by Keyword: Shear Failure

Abstract: Technical papers describing the temperature related degradation of concrete are abundant, and serious damages often occurred in concrete structures subjected to high temperature such as metallurgy factories, although such occurrences were seldom made public. Concrete structures in aluminum electrolysis plants are generally subjected to high temperature emitted from electrolysis cells and cyclic load of heavy vehicles. Besides, hydrogen fluoride emitted from cells and stray current through reinforcement may cause deteriorating effects. In the case of an electrolysis plant built in Niigata in late 1960's, a part of passageway slab collapsed within a year of operation. A few years later, mesh shaped cracks on operation floor and shear cracks on floor beams and columns were observed. And an overall investigation on floor beams of 4 smelter buildings was carried out to determine the extent of deterioration, in 1972. The residual strength decreased linearly with operation term. The extent of strength reduction in "t" years' operation that we named "Deterioration Factor" and limit of lifetime were estimated. Countermeasures to reduce cyclic load and to reinforce floor beams were then taken, as well as the application of the Deterioration Factor to the next electrolysis plant in Shikoku Island. Details of renewed design of S-Electrolysis Plant and degradation of concrete are discussed. These aluminum electrolysis plants in Niigata and Shikoku have stopped operation in 1985 due to the withdrawal of the refining company, and existing smelter buildings have been diverted to another use. Although this paper presents rather retrospective cases, the authors wish this would be still helpful as a case study on degradation in concrete structure due to elevated temperature.

Abstract: One of the fundamental elements applied in reinforced concrete structures are beams. Depending on the proportion of the dimensions and the way of imposing the load, two fundamental mechanisms of destruction are to be distinguished (brittle destruction caused by shearing the supporting zones or flexural destruction in the zone of the span). The present paper provides the results of the analysis of four reinforced concrete beams with the dimensions 4000×400×200 mm, reinforced with steel of varying ductility. The aim of this analysis was to reflect and to provide more detailed information about the phenomena observed in the course of laboratory investigations. The numerical models were constructed in compliance with the system ANSYS, applying volumetric elements Solid 65 and bars Link 8. In order to determine the relation σ-ε of the steel an isotropic model of strengthening according to Misses was implemented in the system ANSYS. The behaviour of concrete was represented making use of the material model Concrete. The parameters applied in the material models were obtained basing on laboratory tests of materials. The results of calculations have been quoted in the paper, as well as their comparison with the results of investigations carried out in the laboratory.

Abstract: Infilling rock joints widely exist in natural rock masses, and the shear failure of infilling rock joints plays an important role in the instability of rock masses. In order to study the shear failure mechanism of infilling rock joints, Particle Flow Code is used to simulate the direct shear test of infilling rock joints. The PFC models with different infilling thickness are established firstly, and then the procedures of PFC simulation are described. In the end, the shear failure process of infilling rock joints with different infilling thickness is simulated. Based on the PFC simulation results, it can be concluded that the shear failure mode changes with increasing infilling thickness, and the shearing of the infilling rock joint rarely gives birth to microcracks in rock due to the existence of the infilling material.

Abstract: The debonding behavior at the interface between carbon fiber-reinforced plastic (CFRP) sheet and concrete is a key problem for the application of FRP plate, which has been widely applied in the civil engineering for rehabilitation and retrofitting of conventional structures. This paper presents the nonlinear finite element analysis results of the CFRP-strengthened high-strength concrete member. On the basis of the test, considering of the bond-slip relationship, explicit finite element is used for simulating the shear failure of CFRP-strengthened concrete, obtain three-dimensional deformation development diagram, describe the failure mode and the relationship between the shearing bond behavior and concrete strength. The FE results coincide with the experimental results.

Abstract: 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.

Abstract: The paper presents some considerations on the experimental tests already carried out on a kind of shear reinforcement of masonry not yet still employed. Indeed that is the use of FRP (fibre reinforced polymer) mesh rebar externally connected to the masonry samples through steel joints to improve their shear performances. The study try to learn final information about the design with this kind of shear reinforcement optimizing the very large experimental investigation on masonry sample subjected to shear diagonal test

Abstract: Through the undamaged and damaged experimental study on frame joints strengthened with CFRP sheets, analyze and compare with two situations in stiffness, ductility, and energy consumption and etc. The results show that the carbon fiber reinforce damaged frame joint is mainly to change its damaged form, satisfied with strong joints, weak component of the design requirements, meanwhile it improves seismic behavior such as strength and stiffness degradation and energy dissipation.

Abstract: A new type of PBL shear connector gets more attention with the rapid development of steel-concrete composite structure. The PBL shear connector's static behavior and influence factors thereof are analysed through experiments. The PBL shear connector's force-transmission mechanism is discussed. The conclusions show that the thickness of perforate plate has significant impact of PBL shear connectors design bearing capacity, shear stiffness and ultimate bearing capacity. According to the thickness of perforate plate, the failure mode of PBL shear connector may appear to flexural and shear failure of perforate rebar, shear failure of perforate rebar or shear failure of perforate plate.

Abstract: Based on micromechanics, an elastic-plastic-brittle damage model of concrete beam reinforced with stick steel is proposed by considering the aggregate gradation curve algorithms and the heterogeneity. In the model, the concrete beam reinforced with stick steel is taken as a five-phase composite material that consists of the mortar matrix, coarse aggregate, bonds between mortar and aggregate, steel plate, and the adhesive layer between steel plate and concrete beam. Through the numerical investigation on shear failure of concrete beam reinforced with stick steel under external force, the results show that the model can clearly simulate microscopic plastic yield, and the initiation and extension of crack. The strength of the steel plate is relatively stronger, so it cant enhance the shear capability of the each side of the beam and the concrete beam bears the larger shear stress, which results that a large number of elements, from the supports to the load points, begin to yield. When the strain of the elements exceeds the yield strength, the elements will produce failure until the failure of the whole specimen. The final failure mode of concrete beam reinforced with stick steel is the shear failure.

Abstract: 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.