Utilization of Ultra High Performance Concrete for Offshore Applications.

超高性能纤维混凝土（UHP-FRC）的发展被认为是结构工程材料应用中最有前途的技术进步之一。这种新材料具有卓越的机械和耐用性。利用纳米技术的颗粒填充概念更进一步生产出这种混凝土。这种新型混凝土的延展性、抗冲击性和能量吸收能力增强，使其成为高抗力结构的理想材料。本研究主要针对混凝土板在静态与冲击荷载作用下的受力特性进行研究。薄板的使用可以用作海上和核安全壳结构等大型重要结构的混凝土模板，或者可以连接到建筑物外部面板，以在未来生产更安全更可持续的结构屏蔽。 这种新材料已用于新的海上希伯伦重力混凝土平台的屋顶、底板和其他部分的不同部分。UHP-FRC具有出色的抗剥落、抗结痂和抗破碎性，使其成为飞溅区波浪力和海冰的理想材料。该新材料非常适合用于海上风力涡轮机结构应用。 UHP-FRC板的开裂、抗拉刚度和配筋率是任何海洋结构物的重要设计因素。本文对超高强度纤维增强混凝土板在落锤冲击载荷作用下的受力性能进行了试验研究、理论分析和数值模拟。将根据径向开裂、剥落、隧穿（结痂）和穿透的临界冲击能量开发四种分析模型。将使用随机减量（RD）方法确定试验前后受试板的动态特性。将确定测试板在不同节点处的固有频率、阻尼比、归一化RD和归一化挠度。在考虑了动态冲击因子（DIF）引起的弹性模量变化后，分别建立了准静态和动态两种情况下的临界冲击能量表达式。 一个数值研究正在开发使用混凝土损伤塑性本构模型适合大变形。在申请人的监督下，在Ryerson实验室进行了一系列实验室测试，以确定识别模型参数。应变率相关的损伤塑性模型是对Drucker-Prager强度假设的修正。拉伸和损伤参数将用于模型。开发的数值有限元模型将用于模拟的影响问题，使用显式动态分析技术。长期目标将集中在成功开发一种有效的薄板设计，用作重要结构的冲击防护。

The development of Ultra High Performance Fiber Concrete (UHP-FRC) is deemed as one of the most promising technological advances in material applications suitable for structural Engineering. The new material exhibits exceptional mechanical and durability properties. Concepts of particle packing using nanotechnology have been taken one step further to produce it. The enhanced ductility, impact resistance and energy absorption capacity of the new concrete makes it an ideal material for use in high resistance structures. The present research investigation will be focused on studying the concrete plate under static and impact loading. The use of thin plate can be used as a concrete form for thick mega important structures like offshore and nuclear containment structures or it can be attached to building exterior panels to produce safer more sustainable structural shield in the future. The new material has been used for different parts on the roof, base slab and other parts of the new offshore Hebron gravity concrete platforms. UHP-FRC has an excellent resistance to spalling, scabbing, and fragmentation, making it an ideal material for wave forces and sea ice for the splash zone. The new material is very well used for offshore wind turbine structures applications. The cracking, tension stiffening and reinforcement ratios of UHP-FRC plate are important design factors for any offshore structure. The impact loading of UHP-FRC plate under dropped weight will be investigated experimentally, analytically and numerically. Four analytical models will be developed based on the critical impact energy for radial cracking, spalling, tunneling (scabbing) and penetration. The Random Decrement (RD) method will be used determine the dynamic properties of the tested plates before and after testing. The natural frequency, damping ratio, normalized RD and normalized deflection will be determined for the tested plates at different nodes. A critical impact energy expressions will be developed after considering the change of the modulus of elasticity due to Dynamic Impact Factor (DIF) for quasi-static domain, and dynamic domain.  A numerical investigation is being developed using a concrete damage plasticity constitutive mode suitable for large deformation. A series of laboratory tests has been conducted at Ryerson lab under supervision of the applicant to determine the identification model parameters. The damage plasticity model under strain rate dependent is considered as a modification of the Drucker–Prager strength hypothesis. Tensile and  damage parameters will be used for the model. The developed numerical FE model will be used on the simulation of the impact problem using explicit dynamic analysis technique. The long term objective will be focused on the successful development of an efficient design of a thin plate to be used as a shield against impact for important structures.