Utilization of Ultra High Performance Concrete for Offshore Applications.

超高性能纤维混凝土（UHP-FRC）的发展被认为是适用于结构工程的材料应用中最有前途的技术进步之一。这种新材料具有优异的机械性能和耐用性。使用纳米技术的粒子包装概念已经更进一步地生产出来了。新型混凝土的延展性、抗冲击性和能量吸收能力增强，使其成为高阻力结构的理想材料。目前的研究主要集中在静载荷和冲击载荷作用下的混凝土板。薄板的使用可以用作大型大型重要结构的混凝土形式，如海上和核围护结构，或者它可以附着在建筑外部面板上，以在未来生产更安全、更可持续的结构屏蔽。***新材料已用于新海上Hebron重力混凝土平台的屋顶、底板和其他部分的不同部位。UHP-FRC具有优异的抗剥落，结痂和破碎性，使其成为飞溅区波浪力和海冰的理想材料。这种新材料非常适合用于海上风力涡轮机结构。*** UHP-FRC板的开裂、拉筋和配筋率是任何海上结构的重要设计因素。本文对UHP-FRC板在落重作用下的冲击载荷进行了实验、分析和数值研究。将基于径向开裂、剥落、隧道（结痂）和侵彻的临界冲击能建立四种分析模型。将采用随机减量法（RD）确定测试前后的测试板的动态特性。测试板在不同节点处的固有频率、阻尼比、归一化RD和归一化挠度将被确定。在准静态域和动态域分别考虑动态冲击因子（DIF）对弹性模量的影响，建立临界冲击能表达式。***目前正在采用适用于大变形的混凝土损伤塑性本构模型进行数值研究。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。基于应变速率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。所建立的数值有限元模型将采用显式动力分析技术对冲击问题进行模拟。长期目标将集中于成功开发一种有效的薄板设计，用于重要结构的防冲击屏蔽。＊＊＊＊＊＊＊＊＊＊＊

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. ***********