Post Local Buckling Behavior and Ultimate Capacity of H–section Beam
Abstract This paper presents a study on the ultimate capacity (maximum strength and plastic deformation capacity) of a thin–walled H–section beam. An experimental study is adopted by subjecting beams under cyclic loading to a large range of deformations with large depth–thickness ratios, which are over or close to the limit value of the current standards. The objectives of the present paper are to reveal the post local buckling behavior and to propose a handy method to evaluate the ultimate capacity. Instead of the commonly used parameter of width and depth–thickness ratio, the normalized thickness ratio WF developed in this study based on the author's previous studies can be regarded as the major parameter to evaluate the ultimate capacity. The relationship between WF and ultimate capacity is examined. The improved criteria for assessing the maximum strength and plastic deformation capacity of an H–section beam is proposed using normalized thickness ratio WF and is shown to be in good agreement with the experiment results.
Monotonic and hysteretic model for H-shaped beams incorporating deterioration behavior owing to the local buckling
Abstract To investigate the collapse behavior of steel frames under the random earthquake, it is essential to grasp the hysteretic behavior of beam members. However, in the large-deformation region, the behavior of beams is difficult to be captured precisely because of the local buckling of the flange plate and the web plate. This paper presents a method to obtain the monotonic curve and the hysteretic curve efficiently for H-shaped beams subjected to bending moment. 96 models for H-shaped beams were designed and analyzed under the monotonic and cyclic loading using finite element analysis. Parameter study was implemented to grasp the influence of width-to-thickness ratio, shear span, and the beam depth. Depending on the numerical analysis, a monotonic model was proposed which can obtain the monotonic curve precisely and efficiently. Consequently, through combining with the modified Ibarra-Medina-Krawinkler hysteretic model, the accuracy for predicting the hysteretic behavior of beams was verified through comparing with the numerical results.
Prediction of a representative point for rail temperature measurement by considering longitudinal deformation
Monitoring rail temperature is very important for determining the safe running speed of trains and to prevent buckling. In general, the maximum variation of the internal rail temperature can be >7 ℃ depending on the point of measurement. However, there is as yet no sufficient information about how to predict the measurement point to represent the thermal deformation due to temperature distribution. In this study, the authors report a new point, called the representative measurement point, at which the rail temperature can be measured. This point considers the average deformation of the rail through structural analysis by adopting experimental and actual rail temperature data. The authors designed and installed a measurement system similar to an actual rail environment. Using the system, various data were acquired (internal/surface rail temperature and weather data) for 10 months. On the basis of these data, an analysis was done to calculate the average deformation point through thermal analysis. Finally, the representative measurement point was proposed as the position at which the average deformation point converges regardless of weather or seasons. The authors believe that the method described herein is advantageous in that it could be used in a high-accuracy temperature-monitoring system and for predicting thermal deformation and buckling.