Shear Behavior of Bamboo Reinforced Concrete Beams

This research work aimed to study the usage of Bamboo strips as shear reinforcement in reinforced concrete (RC) beams. Four beams were considered in this study. The flexural reinforcement for all beams was the same. As for shear reinforcement, one beam was reinforced with conventional shear reinforcement with spacing (s=180 mm), while the other three beams were reinforced with bamboo strips with three different spacings (s=180 mm, s= 90 mm, and s=60 mm). The beams were subjected to a four-point bending test to plot the load-deflection curve for each beam. Results showed that the beam reinforced with bamboo strips spaced at 180 mm has 30% higher shear capacity than the beam with conventional shear reinforcement at the same spacing. Also, as the spacing of bamboo strips decreased, the shear capacity of beams increased nonlinearly.

Effect of Equivalent Load Distribution on the Accuracy of Mapping the Reinforcement Load Deflection Curve in LTP

The formulations of tasks modelling embankments on soft soil, improved with columns and with reinforced load transfer platform (LTP), differ significantly. One of these differences is the distribution of equivalent load modelling part of the load carried by the LTP reinforcement and soft soil. This article analyses the influence of the nature of the load-modelling linear function, i.e., inverse triangular, uniformly distributed and triangular, as well as intermediate distributions. In total, 41 distributions of equivalent load were considered, and the results of the obtained deflection functions were compared with the measurement results of reinforcement deflection for 5 cases of experimental research available in the literature. A measure of the accuracy of mapping the reinforcement deflection curve was proposed as a relative error in relation to the deflection curve resulting from experimental measurements. Based on the analysis of the mapping error, it was determined that among the three commonly used distributions, the inverse triangular distribution shows the best fit in most of the analysed cases. However, not in every single case this is the distribution leading to a solution that best describes the behaviour of the geosynthetic reinforcement.

The Experimental Research on the Mechanical Characteristics of the Newly Designed Fuel Rod Supporting Structure of Spacer Grid

The fuel rod supporting structure of spacer grid is the key to ensure the horizontal and axial position of the fuel rod. On the purpose of improving the neutron economy and simplifying the manufacturing process of the spacer grid, the innovative curved dimple and arched spring have been designed, which could be directly punched from the strip of spacer grid. The mechanical experiments have been performed to acquire the deformation-load curves of dimples and springs on single strap and in-cell supporting structure, which could provide the load and residual deformation at 100% and 120% designed nominal deformation. It has been demonstrated that the designed in-grid cell has a relative stable load at the 100% nominal designed deformation and the test method of the single stripe is representative for the similar load-deflection curve between the spring and the in-grid cell.

Calculating Frictional Losses in Belleville Springs by Geometrical Interpolation

The use of Belleville springs has been proven to be beneficial in tackling the problems related to elastic interaction, creep, differential thermal expansion or in the isolation of seismic vibrations in bolted joints. Because of its high and easily variable spring rates, the use of these springs can also be observed in passive vibration assisted rotary drilling (VARD) tools. Because of relative movement of spring with respect to supporting surfaces and the mating spring surfaces, frictional losses in the spring take place during each compression and relaxation cycle leading to a slightly different load-deflection curve from what has been defined in the literature. The geometry of the spring combined with different stacking configurations complicate the study of frictional losses in these kinds of springs. This work presents a new method to calculate the displacement of different points of Belleville springs during its loading and unloading using geometrical interpolation method. The results of spring displacement are then used to develop a model to calculate frictional load as a function of spring deflection, which is used to analyse load-deflection curves of springs with different dimensional and frictional parameters. The developed methodology is used to plot and understand characteristics curves of four different kind of Belleville springs; High Load, Standard, Force Limiting and Force Adjusting Belleville springs by plotting the graphs for different free-height to thickness and diameter ratios. In the later section of the paper, the proposed methodology has been used to visualize the load-deflection characteristics of Belleville springs used in the p-VARD tool of the Large Drilling Simulator, one of the state-of-the-art drilling simulators at Memorial University of Newfoundland. Results show that understanding of the characteristic curves of different spring configuration helps to plan to drill with desired WOB using a p-VARD tool.

Modeling and robotic handling of a snap-fitting box buckle

Modeling and robotic handling of a plastic box buckle is discussed in this paper. The closing mechanism of the box buckle is simulated to determine the characteristic of the nonlinear load-deflection curve. An intelligent end-effector was designed and manufactured to handle the assembly with a robot. The closing force is measured by a built-in load cell and its values are processed by a micro-controller. The intelligent end-effector can be used in a robotic system, which deals with different snap-fit applications.

Experimentally Effectiveness of Shear Carrying Capacity of Reinforced Concrete Rectangular Beam by using Rectangular, Triangular and Spirally Stirrups.

This paper presents a study of shear behavior of reinforced concrete beam. Generally, shear reinforcement of concrete beam consists of rectangular shape stirrups. when replacing the traditional stirrups by continuous spirally and triangular shape stirrup’s the increase shear carrying capacity of spirally shape stirrups. The spirally shape stirrups reduce the labor cost as well as crack pattern. In this research paper the theoretically shear carrying capacity of rectangular shape stirrups as per design IS456:2000 and experimental shear carrying capacity of rectangular shape stirrups is obtained and that value compared to the spirally and triangular shape stirrups. The present experiment carries 27 beam having cross section 700mm x 150mm x 150mm each set consist 9 beam of rectangular, spirally and triangular shape shear reinforcement with spacing 70mm, 90mm, 110mm. all the beam was tested using four-point loading after 28 days curing. The test result include shear carrying capacity, load-deflection curve, crack pattern. Take a test after 28 days the spirally shear reinforcement improved shear carrying capacity as well as ductility of beam compared to the rectangular and triangular shape stirrups. Hence spiral shear reinforcement shows better result as well as crack performance also deflection at mid span.

Comparison of different approaches for determining the residual post-cracking strength index of fiber reinforced concrete for bridges

In Canada, there are different approaches to evaluate the performance of fiber reinforced concrete (FRC) for bridges based on the residual post-cracking strength index (Ri). They involve different combinations of test methods ASTM C78, ASTM C1399, and ASTM C1609. The aims of this study were to assess all possible (existing and new) methods to determine the Ri values, and capture the major differences between the current Canadian Highway Bridge Design Code (CHBDC S6-14) and the City of Winnipeg specification’s approaches, as a case study. Flexural tests (ASTM C78, ASTM C1399, and ASTM C1609) were performed on 60 FRC beams (100 mm × 100 mm × 350 mm) prepared from concrete provided by four ready-mix concrete suppliers according to City of Winnipeg’s bridge deck specifications for a project built in Winnipeg. The results showed that all the methods implemented herein for calculating the Ri of FRC gave comparable results. However, by using Method V, all required parameters (first peak load and residual loads at specified deflections) could be directly extracted from one load–deflection curve obtained from ASTM C1609. In addition, when using this method, the Ri can be calculated for each specimen, which enables quantifying the magnitude of variation from average values. Since this approach also requires fewer number of specimens, reducing time and cost of testing, it has been adopted by the City of Winnipeg in bridge specifications for FRC.

Study on toughness and toughening mechanism of cement-based fiber materials

In order to improve the character of common cement mortar which are brittle and easily cracked, andtotake advantage of the local materials, abandoned fishing nets was used toform get the cement-based fiber materials. In this study, the influence of the amount and length of abandoned fishing nets on the mechanical properties of cement mortar and its mechanism were discussed. Four different lengths of abandoned fishing nets were adopted under four kinds of dosages to mix with mortar and make a total of 16 test blocks. Then the flexural strengths of the prepared test blocks were tested, and the load-deflection curve of the test block was obtained. The results showthat the residual strength after the test block after which reachesthe peak load in the flexural test generally increases with the increase of the fiber content and the length of the fiber, but when the dosage and length increase to a certain range, the influences becomecomplicated. The crack propagation simulation byAbaqus further revealed the reinforcement mechanism, and it can be concluded thatthe bridging between the fiber and the matrix has a great influence on the character toughness.