Development of Composite Yielding Dampers

结构的被动控制在技术上仍在发展，对系统行为、响应预测方法、设计指导和现场经验的理解不断加深。由于日本在保护结构免受地震和风力影响的创新被动控制措施方面的重大研究投资，有关被动控制系统的行为、设计和实施的宝贵信息正在开发中。日本最近发展的一种新型被动控制系统是一种屈服支撑阻尼器。屈服支撑包含一个具有大的延性能力和相对较低的屈服强度的单一钢板，该钢板被包裹在灌浆填充管中，但不与灌浆结合。该装置的关键概念是，屈服发生在外包钢板同样的拉伸和压缩载荷循环和系统具有稳定的滞回耗能能力。提出了一种新型的屈服装置，它建立在屈服支撑的经济优势的基础上，但允许定制屈服元件材料以实现特定的性能要求，并采用非粘性介质来限制屈服元件。这两个创新结合起来提供了阻尼器的受控屈服后斜率，即使在建筑框架可能显著屈服和软化的极端地震期间，该阻尼器也保持结构的自定心能力;提供了不侵犯现有专利的普遍适用的限制技术;消除了脱粘界面处的装置的高精度设计、细节设计和制造;降低了阻尼器成本;破坏性地震后易于维修/更换屈服元件;能够进行检查;并提供额外的摩擦阻尼，这可能有利于减轻风响应。这种新型装置被定义为复合屈服阻尼器（CY-阻尼器），CY-阻尼器的综合属性可以提供比现有装置显著的技术和经济优势。本文提出了一个将实验和分析相结合的研究方案，以研究CY阻尼器在建筑结构中的应用。拟议研究项目的主要目标是：（1）开发原型CY-阻尼器，（2）表征单个CY-阻尼器的结构性能并优化阻尼器性能，（3）确定具有CY-阻尼器的建筑框架在不同震级地震下的行为，（4）开发分析模型来描述CY-阻尼器和CY-阻尼系统的行为，（5）为CY阻尼器的性能化设计提供了指导。这些目标将通过与日本研究人员团队合作来实现，他们是该系统在日本的主要开发者。研究人员之间的专业关系和研究合作正在进行中，在拟议研究计划的所有阶段都将进行重要的资源和信息交流。提出了在反复荷载作用下的小型和大型CY阻尼器试验。研究的参数包括：（1）不同材料的应用，包括高强度钢和低强度钢或其他高性能材料的组合，（2）不同约束材料和板细长参数的研究，和（3）高周低幅疲劳下的长期耐久性。一个原型多层多间钢框架建筑将被用来促进现实的测试样本的发展，并允许不同的阻尼器设计之间的比较。与实验任务相一致，将产生与现有分析程序兼容并与实验观察到的响应相关的分析模型。将开发简化和实用的分析方法，包括等效线性化技术，以预测响应并制定实用的设计指南。

Passive control of structures is still evolving technologically, with increasing understanding of system behavior, response prediction methodologies, design guidance, and field experiences. Valuable information regarding behavior, design, and implementation of passive control systems is being developed in Japan due to their significant research investment in innovative passive control measures for protection of structures against both seismic and wind forces. One type of innovative passive controlsystem that has been developed recently in Japan is a type of yielding brace damper. The yielding brace contains a single steel plate with large ductility capacity and relatively low yield strength that is encased in a grout filled tube, but is not bonded to the grout. The key concept of the device is that yielding occurs in the encased steel plate equally for both tensile and compressive loading cycles and the system exhibits stable hysteretic energy dissipation capability. A new type of yielding device is proposed which builds on the economic advantages of the yielding brace, but allows tailoring the yielding element materials to achieve specific performance requirements and employs noncohesive media to confine the yielding elements. These two innovations combined provide controlled post-yield slope of the damper that maintains self-centering capability of a structure even during an extreme earthquake when the buildingframe may significantly yield and soften; provide a generally applicable confining technique that does not infringe on existing patents; eliminate high-precision design, detailing, and fabrication of devices at the debonding interface; lower damper cost; ease of repair/replacement of yielding elements after a damaging earthquake; enable inspection; and provide additional friction damping which may be beneficial for wind response mitigation. This new device is defined as a composite yielding damper (CY-damper).The combined attributes of CY-dampers may provide significant technical and economicadvantages over existing devices. A research program, integrating both experimental and analytical components, is proposed to investigate the application of CY-dampers for building structures. The primary objectives of the proposed research project are to: (1) develop prototype CY-dampers, (2) characterize the structural performance of individual CY-dampers and optimize damper properties, (3) determine the behavior ofbuilding frames with CY-dampers under varying magnitude earthquakes, (4) develop analytical models to describe the behavior of CY-dampers and CY-damped systems, and (5) provide guidance for the application of CY-dampers directed toward performance based design. These objectives will be achieved by working in collaboration with a team of Japanese researchers who are the primary developers of this system in Japan. Professional relationships and research collaboration are on-going between the researchers and significant resource and information exchange will take place throughout all phases of the proposed research program. Small and large-scale CY-damper tests under reversed cyclic loading are proposed. Parameters to be studied include: (1) application of different materials including combinations of high and low strength steels or other high-performance materials, (2) investigation of different confining materials and plate slenderness parameters, and (3) long term durability under high-cycle low-amplitude fatigue. A prototype multistory multibay steel frame building will be used to facilitate development of realistic test specimens and permit comparison between different damper designs. In concert with experimental tasks, analytical models will be produced which are compatible with available analysis programs and correlate experimentally observed response. Simplified and practical analysis methods including equivalent linearization techniques will be developed to predict response and develop practical design guidance.