A Study on Structural Response Behavior and Strength Evaluation Systems of Submerged Floating Structures with Tension Legs in Waves

(1)首先研究了具有张拉腿的海底隧道结构在不规则波浪中的弹性响应特性。首先，分析提出了一种基于弹性基础的简梁在规则斜波条件下动力响应的简化估计方法。然后，利用上述分析结果，结合不规则海浪谱，提出了不规则海浪条件下动力特性的简化估计方法。其次，提出了在极端波浪荷载作用下主体开裂破坏可靠度估计的极限状态模式。最后，通过在一些不规则海况条件下的1000m级具有张拉腿的海上隧道结构的数值算例，研究了方法的适用性。并对主体开裂破坏的短期响应特征和可靠度水平进行了数值计算。通过灵敏度分析，探讨了裂缝破坏的临界弯矩、最大弯矩期望值相关的弯曲刚度和系泊刚度对可靠性水平的影响。(2)其次，在线性长波理论和薄板理论的一些假设下，研究了有张腿支撑的水下浮体结构在规则波中的水弹性特性。在此基础上，数值研究了含沉板和张拉腿的浮式结构模型在规则波中的水弹性特性。其次，为了验证理论结果的有效性，对规则波中的基本模型进行了实验研究。在低频范围内，频率响应幅值的实验结果与理论结果吻合较好。最后，对某1000m级水下浮式结构进行了数值研究，该浮式结构采用双壳结构进行试验设计。根据分析结果，研究了结构挠度和弯曲应力的频响幅值特征。(3)为了研究三次重复应力作用下钢材料的疲劳行为，对其温度和滞回能量特性进行了实验研究。根据试验结果，考虑了疲劳寿命与这些行为之间的关系。(4)试验研究了预应变对完全重复应力下钢材料疲劳性能的影响。根据这些结果，考虑了疲劳寿命与温度和迟滞回线能量的关系。(5)作为海洋管道结构倒塌行为基础研究的一部分，采用非线性有限元方法数值研究了复合荷载和腐蚀部分减厚对弯矩和侧压力联合作用下圆管倒塌行为的影响。少

(1) The first research is concerned with the elastic response behavior of marine tunnel structures with tension legs in irregular waves. First, a simplified estimation method for dynamic responses under regular oblique wave conditions is analytically presented using a simple beam on an elastic foundation. Then, a simplified estimation method is presented for the dynamic behavior under irregular wave conditions by using above analytical results and combining irregular sea wave spectra. Next, the limit state mode is presented for estimating the reliability level for cracking failure of the main body under extreme wave loads. Finally, the applicability of the methods is investigated through numerical examples carried out for a 1,000m-class marine tunnel structure with tension legs under some irregular sea state conditions. And characteristics of the short-term responses and reliability levels for the cracking failure of the main body were numerically shown. Effects of the critical moment … More for cracking failure and bending and mooring rigidities concerning with the expected value of the maximum bending moment on reliability levels are also investigated by sensitivity analysis.(2) Next, the hydro-elastic characteristics of a submerged floating structure supported with tension legs in regular waves is investigated under some assumptions of the linear long wave theory and thin plate theory. Then, the hydro-elastic characteristics of a floating structure model with a submerged plate and tension legs in regular waves are investigated numerically. Next, in order to demonstrate the validity of theoretical results, an experimental study was carried out for a basic model in regular waves. It is found that experimental results for the frequency response amplitude were in good correspondence to theoretical results in the low frequency range. Finally, numerical studies are carried out for a 1,000m-class submerged floating structure whose was composed of double hull structure under trial design. From analytical results, characteristics of the frequency response amplitude for deflection and bending stress of the structure are investigated.(3) In order to investigate fatigue behavior of steel materials under triple repeated stress, characteristics of behaviors on temperature and hysteresis-loop energy are experimentally investigated. The relation between fatigue life and these behaviors is considered using these experimental results.(4) The effect of pre-strain on fatigue behavior of steel materials under perfectly repeated stress is experimentally investigated. From these results, the relation between fatigue life and behaviors on temperature and hysteresis-loop energy is considered.(5) As a part of basic study on the collapse behavior of marine pipeline structures, effects of combined loads and partially reduced thickness due to corrosion on collapse behaviors of circular tubes under combined with bending moment and lateral pressure are numerically investigated by using a non-linear finite element method. Less