Papers by Keyword: Fatigue Load

Abstract: Through the experiment of eight lightweight aggregate reinforced concrete beams under static loading and fatigue loading with constant amplitudes, the deformation rule under fatigue loading was analysed, the rigidity calculation means and formulations of lightweight aggregate reinforced concrete beam under fatigue loading were also discussed.

Abstract: Based on the Palmgren-Miner linear cumulative fatigue damage theory, the blade root fatigue loads in different effective turbulence intensities were calculated and analysed. The results show that when the air density and the wind speed are constant, the blade root fatigue loads increase linearly with the effective turbulence intensity increasing, and the slopes increase linearly with the wind speed increasing. According to these results, the main source of the blade root fatigue loads under different wind conditions can be estimated to provide a theoretical basis for WTGS type selection in the special sites.

Abstract: The purpose of this paper is to present the results of observation of material degradation process in steel samples under combined conditions of static and cyclic dynamic loading, using selected electromagnetic NDT methods. To evaluate damages a Barkhausen noise observation, an AC magnetization, a magnetic flux leakage and eddy current method were used.

Abstract: In this paper, in combination with the specific conditions of light rail traffic volume, fatigue load spectrum parameters of light rail support are to be determined by background project light rail line 3 of Chongqing Caiyuanba Yangtze Bridge, through which the internal force history is then calculated. Three million constant amplitude fatigue loads that the test needs are finally determined through linear fatigue damage cumulative theory.

Abstract: Research on cement concrete under corrosion fatigue is mainly focused on experimental research which is difficult to reveal the physical mechanism of deformation and failure. Models for sulfate attack have been based on the different scientific fields of engineering, mechanics, physics, and mathematics. For this problem, the numerical solution of the cement concrete under the fatigue corrosion is established with establishing diffusion reaction equation basing on Fick's second law under the coupled action of corrosion fatigue and obtaining the stress-strain response

Abstract: To study the relation between stress and the Metal Magnetic Memory Testing (MMMT) signal Hp(y) of ferromagnetic structure, a material mechanics experiment using X60 pipeline steel specimens under tension load and fatigue load is performed. The results show: The value of MMMT signal in elastic stage is small under tension load, while the value of MMMT signal in plastic stage is large. In the process of static tension, the zero crossing point (ZCP) of initial MMMT signal curves shift to the fracture position, and there is only one ZCP of MMMT signal curve at the position of fracture area. In the process of low-load fatigue, the shape and distribution of MMMT signal curves are similar under different cycle numbers of fatigue load. The value of MMMT signal increases a little with the increase of cycle number of fatigue load, and then increases sharply when the specimen is to be fractured. There is only one ZCP of MMMT signal curve at the position of fracture area in the process of fatigue loading.

Abstract: This paper summarizes the results and discussion of experimental studies on corroded, reinforced concrete 4 point beam test specimens (120 mm x 200 mm x 1700 mm) repaired by external bonding of carbon fiber reinforced polymer (CFRP) composite laminates to the tensile face of the beam. The primary parameters investigated in this experimental study were distortion, stress distribution, and ultimate load capacity of the corroded reinforced concrete beams. The results indicate that the load capacity and the rigidity of repaired corroded beams by CFRP were significantly higher than the un-repaired, corroded beams. Beams with a low degree of corrosion damage, repaired by CFRP, were still able to demonstrate good mechanical properties after a short-term fatigue loading.

Abstract: This paper present results and discussions on an experiment study on the impact of corrosion ratio to the RC beams under fatigue and monotonic loads. Seven reinforced beams with the same steel type, concrete cover, steel diameter and ratio were test. The effect of corrosion ratio on flexural stiffness of these RC beams was discussed. Based on fatigue and monotonic test for these beams, the most investigated parameters in this experimental study were distortion, stress distribution, ultimate load of corroded reinforced concrete beams. The results indicate that the effect of corrosion ratio on flexural stiffness of RC beams is very obviously, curvatures of corroded beams increase monotonically with degree of corrosion. Fatigue loading has great impact on the performance of corroded RC beams; it can reduce the ultimate strength and ductility of the beams significantly as corrosion ratio increase.

Abstract: This paper is focused on developing fatigue-load model for highway bridges based on the measurements data of WIM (Weigh-in-Motion) in China. In this paper, based on the analysis of vehicle flow data collected from six toll stations on Jing-Fu Highway which is one of the busiest highways in China, spring festival index and month index of vehicle flow are obtained. The finite element models are established, and the vehicle flows are modelled by using Monte Carlo method as dynamic load applied on the nodes of the models. This paper presents a fatigue truck model for Jing-Fu Highway bridges, which may also be used for other highway bridges in China. In order to validate the model, strain time histories were obtained through field strain measurements for 3 existing bridges on this highway. In addition, comparison among the model introduced in this paper and the models in foreign codes as well as the models developed by other researchers is presented.

Abstract: In this paper, the feasibility of damage detection and characterization using the EMI technique on high cycles fatigue induced damage is investigated. Cyclic tensile load is applied on a lab sized aluminium beam up to failure. Piezo-impedance transducer in the form of PZT patch (lead zirconate titanate) is surface bonded on the specimen for crack detection. Progressive shift in admittance signatures measured by the PZT patch corresponding to increase of loading cycles reflects effectiveness of the EMI technique in tracing the process of fatigue damage progression.