Fatigue design consideration in columns under wave cyclic loading Research Paper

Fatigue design consideration in columns under wave cyclic loading - Research Paper Example Studies reveal that there are significant calculations and estimations that need to be considered to determine the effects of wave conditions on these structures. The present study focuses on these factors, and the types of fatigues that are possible. This would bring into light the necessity for experts to consider an extensive study on the structures, the materials employed and the conditions of the waves such that effective measures may be applied in the process of construction. Introduction: Considering the issue of cyclic wave loading, it is necessary to understand that both cyclic strains and residual strains or strains that are permanent in nature are developed when a sequence of cyclic loads affect the underground soil. The permanent or residual strains stay behind at the end of each cyclic load reflecting a growing effect that gets accumulated with the effects left by earlier storms. Greater attention has been provided to evaluations of peak cyclic displacements that occur a long with a storm. However there are greater needs for studies on issues of permanent displacement. While considering these issues, it is also necessary to take into consideration the relationships among the properties of the soil, cyclic loading as well as well as the residual strains and the shear stress (Marr et al, 1981, pp.1129-1130). Concrete components used in offshore structures encounter forces of strong wave owing to frequent storms and are open to tremendously rigorous conditions of the environment leading to decay of steel that is fixed in the structure and worsening of the concrete material. Fatigue loading tests are conducted in this regard in order to obtain fatigue properties of column joints that are already stressed, the results of which can then be compared to those obtained from static loadings. Considering joints and columns in the offshore structures, it has been found that many types of offshore structures constituting concrete that is already stressed have be en built up with intentions to make use of the space of the offshore and to take advantage of the natural resources in offshore regions (Kiyomia et al, 1988, p.139). The present study focuses on the concept of fatigue design implemented in columns under cyclic wave loading. Literature Review: Kiyomia et al (1988, pp.139-140) in their studies had discussed about the determination of the conditions of waves for fatigue designs. According to them the waves of sea are an assortment of numerous sinusoidal waves reflecting different periods of time and amplitudes. Moreover, the conditions of the wave vary based on the site of the construction. The conditions of the waves at every location need to be estimated and assessed by statistical procedures by means of wave records. â€Å"The relationships between the numbers of waves and the wave heights are needed to determine the fatigue limit state according to the service life of the facility when using Miner's rule for calculating the fatigu e strength of the joints. To estimate the serviceability of the joints, the wave conditions, expressed as the number of waves and wave heights over a period of 1 month to 1 year, are needed†. A study considered by International Maritime Organization discussed that the likelihood of damages to fatigue designs owing to cyclic wave loading need to be taken concern of in the â€Å"design of self-elevating and column-stabilized units† (International Maritime Organization, 1990, p.72). Such analyses of the fatigue designs are required to be conducted with the studies based on the intended mode and the operations involved in the designs of the units. Also, the analysis needs to consider the life of the intended design and the convenience of individual structural