Papers by Keyword: Reinforcement Ratio

Abstract: This paper deals with failure modes of a steel-concrete-steel sandwich loaded by pure in-plane shear. Current research together with the developed models imply that increase of reinforcement ratio leads to decrease of ductility and possibly to change a failure mode from yielding of steel in tension to crushing of concrete in compression which results in brittle failure. In order to give a reader basic information about in-plane shear behavior of a steel-concrete-steel sandwich, an analytical model is introduced. Japanese experimental program that researched a behavior of SCS panels with reinforcement ratio 2.3%, 3.2% and 4.5% is also shown. In addition to the effect of changing the reinforcement ratio, the experimental program also investigated the effect of the transverse steel plate on the ductility of test panels with a degree of reinforcement of 3.2%. The next chapter describes the methodology used by the author to model the individual parts of the model, the loads, and especially the method of supporting the model. This is followed by the presentation of the results of the analysis on the calibration and extrapolation models. Finally, a discussion is conducted on the agreement of the analysis results on the calibration models with the Japanese experimental results, followed by an evaluation of the analysis results on the extrapolation models. According to the results on the extrapolation models the critical degree of reinforcement at which a change in the failure mode of the structure occurs under in-plane shear loading is around 13%.

Abstract: Textile Reinforced Mortars (TRM) include a series of innovative strengthening systems suitable for conservation interventions since inorganic matrixes, instead of polymeric resins, are employed. Recent research supported the definition of guidelines on testing methods for TRM systems applied to masonry, but further investigation is needed to clear out the role played by the numerous factors affecting the strengthening capacity. In this study, an experimental campaign on basalt-fibre TRM systems was carried out. A series of tensile and single-shear bond tests are compared. Samples differ for fibre reinforcement ratio, textile layout and the number of textile layers, while the lime-based mortar matrix is the same for all specimens. For tensile tests, results show that, after a mortar-cracking phase, a third, substantially linear phase, during which the textile response is dominant, occurred for specimens failed both for textile tensile rupture and textile slippage. For shear bond tests, results showed that increasing the reinforcement ratio tightening textile mesh is not as beneficial as increasing textile layers, i.e. active bond surfaces.

Abstract: Fibre Reinforced Cementitious Matrix (FRCM) composites are becoming largely adopted for retrofitting masonry structures. These materials offer several advantages in comparison to Fibre Reinforced Polymer (FRP) composites, such as good resistance to fire and high temperatures, vapour permeability, possibility to be applied on wet surfaces, higher compatibility with the masonry substrate. However, the tensile behavior of FRCM materials is more complex compared to FRP composites, due to the limited tensile strength of the cement-based matrix. For this reason, FRCM materials require appropriate tensile characterization and, in this context, the use of non-conventional measurement systems, such as the Digital Image Correlation (DIC), can offer numerous advantages. This work presents an experimental study on the application of the DIC technique for the tensile characterization of Basalt Fibre Reinforced Cementitious Matrix (BFRCM) strips. Tensile tests were carried out on three series of specimens reinforced with one, two or three layers of basalt grid in order to investigate the effect of the reinforcement ratio on the tensile response of the composite strips. The test setup and the calibration of the DIC analyses are discussed. It is shown as the DIC allows obtaining detailed information on the tensile response, including the evaluation of the full strain field on the surface of the BFRCM strips and the location of cracks. Results are discussed also in terms of stress-strain curves and failure modes.

Abstract: In this study, confined masonry specimens with regular arranged openings are tested in order to study the influence of different enhancements of the columns on seismic failure modes. In particular, five brick masonry walls and three half-scale two-storey masonry structures are tested under quasi-static loads. The experimental results show that increasing column ratio improves the seismic behavior of the wall specimens to some extent, but an excessive reinforcement ratio of the columns decreases the ductility. The global failure mode of the two-storey masonry structures is modified by inserting iron wires in the mortar bed joints, improving the structural collapse resistant capacity effectively.

Abstract: The development of marine economy brings with it a need for marine buildings and port structures that require concrete. If these buildings were built with sea sand concrete mixed with sea water instead of traditional concrete and replaced FRP reinforced steel, raw materials can be procured locally, saving time and cost. Based on the above considerations, 8 GFRP reinforced SS-concrete (concrete with sea sand and sea water) beams were prepared to understand their workability and strength as their reinforcement ratio increases. Results show that an increase in reinforcement percentage, leads to an increase in strength and decrease in bonding property. Based on these experimental results it is assumed that only the horizontal sections are feasible. Although GFRP reinforced SS-concrete failure is primarily due to brittleness, obvious signs such as fully developed cracks and large deflections can be seen prior to the failure. So in the design, the ductility of the GFRP reinforced concrete with sea sand and sea water can be assured through controlled load and reinforcement rates.

Abstract: In this study, ductility of members with ultra-high performance concrete was investigated using moment-curvature analysis for the verification of safety under large deformation of ultra-high performance concrete structural members. For the analysis of members with ultra-high performance concrete, mathematical stress-strain model was selected among the results conducted by other researchers on the compressive and tensile behavior of high strength concrete and fiber reinforced concrete. According to the investigation on ductility of members with ultra-high performance concrete, decrease of ductility was observed with increase of tensile strength of concrete under the same reinforcement ratio. Members with 2~3% of reinforcement ratio, which usually be used in the field engineering, show the decrease of ductility with increase of fiber volume fraction. As a results of parametric study, limitation of maximum reinforcement ratio ( or limitation of net tensile strain ) suggested by current design code is not safe when using ultra-high performance concrete.

Abstract: Bearing capacity tests of three reinforced concrete lining segments were carried out. The effect of the loading method and ultimate bearing capacity of the reinforced concrete lining segments and the maximum displacement and reinforcement ratio on the failure mechanism was analyzed based on the simulation results. The simulation results show that the yield load and ultimate load of the lining segments can be effectively increased because of the axial force effect. the loading method on the full surface was proposed. The the ultimate load and yielding load increase as the reinforcement ratio increase is radial distribution in the state.

Abstract: Finite element analysis is carried out on the dynamic splitting tensile mechanical properties of reinforced concrete with LS-DYNA. The impact of strain rate and reinforcement ratio on the dynamic tensile strength and failure mode of reinforced concrete is considered in the calculation. The result shows that the form of reinforcement and reinforcement ratio has a greater impact on the failure mode and tensile strength of concrete. The dynamic splitting tensile strength of reinforced concrete has a certain strain rate effect and its splitting tensile strength increases with the strain rate; the splitting tensile strength of reinforced concrete also increases with its reinforcement ratio.

Abstract: In this paper, using elastic-plastic fiber unit model for a continuous beam bridge structure and foundation to analyses the nonlinear seismic response of pier and pile foundation considering pile-soil interaction and the different types of seismic wave on the pile foundation and the pier dynamic response, focusing on the development of plastic zone and dynamic response of structure under different pile-pier reinforcement ration conditions. The results show that, with the pile pier reinforcement ratio increases, the response plasticity of pile and pier show a different trend; so pile-pier reinforcement ration is an important factor of dynamic characteristics for the bridge pier supported by group piles system; the pier reinforcement ratio not only impact on development of the plastic zone of the pier, but also impact on the pile. In addition, different types of seismic waves on the structure are different, the long-period seismic waves maximum, followed by inland direct seismic waves, plate boundary seismic wave minimum.

Abstract: Seven reinforced recycled-concrete beams were tested to study their flexural resistance considering the variations of the strength of recycled-concrete and the reinforcement ratio of longitudinal tensile rebar. The aggregates of recycled-concrete comprised the machine-made sand and the recycled coarse aggregate. The failure state of normal section and the flexural resistance of reinforced recycled-concrete beams affected by the strength of recycled-concrete and the reinforcement ratio were discussed. The results show that the failure states of reinforced recycled-concrete beams were similar with those of the ordinary reinforced concrete beams. The flexural resistance was controlled by the reinforcement ratio, and influenced increasingly by the strength of recycled-concrete with the increase of reinforcement ratio. The failure resistance of reinforced recycled-concrete beam can be calculated by the method for ordinary reinforced concrete beam specified in current design code GB50010-2010.