| Today we are facing a global crisis of energy, and in offshore of China there lie many marginal fields that need exploiting urgently, yet guiding-pipe platforms aren't adequate for these shallow water fields. So it is necessary to develop some neotype platform that should be multi-function and mobility. In order to cater this purpose, a minitype of lightweight concrete platform with a single tank and five legs is designed.Aim for the topic-Study of Prestressed Lightweight Concrete Platform, from selecting style of the platform, to matching concrete material and admixture, to designing and building the model, to carrying out experiments of temperature field and stress performance, and analysis of finite element, some research work have been done as follows:1. Through analysis of geological and environmental conditions of China Bo-sea area, according to types of concrete platforms foreign existing, a new type of concrete platform is corroborated which is suitable for exploiting shallow-water oil fields of Bo-sea area. The tank model with scale of 1:5 is built and model test is carried out. By dimension analysis, resemblance between archetype and model is confirmed.2. In terms of construction features of concrete platform on offshore, some requirements for concrete strength, durability, and constructivity are approached. Being lightweight aggregate, the chemical mineral constituents and physical mechanics properties of lytag are analyzed. Meanwhile properties of haydite concrete using lytag as coarse aggregate are also studied. The influences on lightweight concrete qualities by introducing wollastonite and chemical admixtures are researched which proves the important roles of wollastonite and admixtures in construction of concrete platforms. In order to estimate Young's modulus of lightweight concrete more accurately than existing empirical formula, three regression equations are obtained in light of material properties test.3. Temperature is main load in the course of experiment. In order to analyze stress, strain and deformation under temperature effect, and prepare for measuring and processing data correctly, thermal results such as heat output and hear error caused by temperature-change are assayed, and difference among fact strain, creating stress strain and measuring strain often mixed up each other is discussed. Besides, this paper studied stress, strain and deformation of restraining and free structural member under the conditions of stabilize linear, stabilize nonlinear and unstable temperature field respectively. The quantitative relations of the three kinds of strains are analyzed, at the same time the expressions of deformation, stress and strain are derived under above restraint and temperature-change conditions. The problem under which conditions temperature-change will generate stress and which not is studied.4. By researching heat conduction of air interlayer, the coefficient of heat transmission expression of vertical space layer is derived in stable condition. Utilizing method of function extremum, it is proved that there lies minimum coefficient heat transmission in sealed vertical air layer, that is to say there exists the minimum theoretical equivalent conductivity factor. Furtherly, the equation of the most excellent thickness of air interlayer is obtained.5. In response to heat conduction test, air heat-insulation course is proved to work well, it reduces temperature difference of tank walls greatly and prevents cracks effectively. By establishing mathematic model and finite element model, steady temperature field of the tank is analyzed. And the calculating results are compared to the experimental ones, which agree with each other. According to the obtained conclusions, some problems should be paid attention to in practical applications are presented. .6. Through experiment study of tank model under prestress, water pressure, temperature action, external loads, and coactions of all the loads, stress characters of various parts of concrete tank are...
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