A System for Multi-Axial Subassemblage Testing (MAST)

小乔治·布朗地震工程模拟网络（NEES）项目是由美国国家科学基金会主要研究设备计划资助的一个项目。根据NEES计划，该合作协议将在明尼苏达大学双城校区建立NEES大型实验室地震工程研究实验基地。大学将设计、购买、建造、安装、调试和运行一个多轴组件测试系统（MAST），用于结构地震工程实验。该设备将于2004年或更早投入使用，并将作为国家共享使用的NEES设备站点进行管理，具有远程观测和远程操作能力，到2014年提供新的地震工程研究测试能力。该NEES设备站点将通过大学的阿比林连接连接到NEES合作实验室，具有千兆以太网功能。共享使用的获取和培训将通过NEES联盟进行协调。该奖项是对提交给项目招标NSF 00-6“NEES：地震工程研究设备”的提案进行同行评审的结果。Multi-Axial subassembly Testing （MAST）系统提供了一种综合的方法来模拟建筑物和桥梁在中、大地震中的结构反应，将大型结构测试与结构部件和系统的三维非线性分析联系起来。MAST系统可以对大型结构组件进行多轴循环和拟动力测试，例如梁柱框架系统、墙壁、桥梁和桥墩的部分。MAST系统由高性能执行器、十字头（用于顶部和底部反应表面的大型钢制焊接件）、带有六自由度（DOF）软件（控制系统）的数字控制器、液压分配系统和l型反应壁系统组成，该系统可为水平执行器提供横向负载阻力。MAST系统使用6自由度控制器通过8个执行器（4个垂直和2对水平正交执行器）来定位顶部十字头，以直接和可复制的方式应用真实的变形和加载状态。六自由度控制软件采用先进的控制技术，通过对八个十字头执行器的实时同步控制来定位十字头的位置。该系统不仅可以控制空间中点的位置，还可以控制空间中的平面。这一特点使得它可以应用双轴控制结构，如多湾子组合或墙壁。它还允许应用纯平面平移，以及应用梯度来模拟倾覆的可能性（例如，多舱框架或墙壁摇摆柱的轴向载荷梯度）。该系统可以对试验结构施加完整的六自由度载荷条件，从而提供了一种新的大规模试验能力，将增强地震工程界对复杂破坏状态的理解。MAST系统将位于明尼苏达大学双城校区土木工程系的结构工程实验室。该大学已承诺分担87.5万美元的费用，用于改善实验室基础设施，以适应MAST系统。明尼苏达大学将把MAST系统整合到其研究项目以及本科和研究生课程中，为研究人员、从业人员和行业专业人员实施MAST合作实验室，以促进MAST系统的实验、计算和技术转移方面，并为外部研究人员提供培训机会。

The George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Program is a project funded under the NSF Major Research Equipment Program. This cooperative agreement, under the NEES Program, establishes a NEES large-scale, laboratory earthquake engineering research experimentation site at the University of Minnesota-Twin Cities campus. The University will design, purchase, construct, install, commission, and operate a Multi-Axial Subassemblage Testing (MAST) system for structural earthquake engineering experimentation. This equipment will be operational by 2004 or earlier and will be managed as a national shared-use NEES equipment site, with teleobservation and teleoperation capabilities, to provide new earthquake engineering research testing capabilities through 2014. This NEES equipment site will be connected to the NEES collaboratory through the University's Abilene connection, with Gigabit Ethernet capabilities. Shared-use access and training will be coordinated through the NEES Consortium. This award is an outcome of the peer review of proposals submitted to program solicitation NSF 00-6, "NEES: Earthquake Engineering Research Equipment." The Multi-Axial Subassemblage Testing (MAST) system provides an integrated approach to the simulation of structural response of buildings and bridges in moderate and large-scale earthquakes, linking large-scale testing of structures with three-dimensional nonlinear analyses of structural components and systems. The MAST system enables multi-axial cyclic and pseudo-dynamic tests of large-scale structural subassemblages, such as portions of beam-column frame systems, walls, bridges, and piers. The MAST system consists of high performance actuators, cross heads (large steel weldments for the top and bottom reaction surfaces, a digital controller with six degrees-of-freedom (DOF) software (control system), a hydraulic distribution system, and an L-shaped reaction wall system to provide lateral load resistance for the horizontal actuators. The MAST system uses the six DOF controller to position the top cross head using eight actuators (four vertical and two horizontal pairs of orthogonal actuators) to apply realistic states of deformations and loading in a straightforward and reproducible manner. The six DOF control software employs advanced control technology to locate the position of the cross head through real-time simultaneous control of the eight cross head actuators. This system not only enables control of the position of a point in space, but also of a plane in space. This feature makes it possible to apply biaxial control of structures such as multi-bay subassemblages or walls. It also enables the application of pure planar translations, as well as the possibility of applying gradients to simulate overturning (e.g., axial load gradient in the columns of a multi-bay frame or wall rocking). With this system, a full six DOF loading condition can be imposed on the test structure, thus providing a new large-scale testing capability that will enhance the earthquake engineering community's understanding of complex failure states. The MAST system will be located in the Structural Engineering Laboratory in the Department of Civil Engineering on the University of Minnesota, Twin Cities campus. The University has committed to $875,000 in cost sharing for laboratory infrastructure improvements to accommodate the MAST system. The University of Minnesota will integrate the MAST system into its research program and undergraduate and graduate curricula, implement a MAST collaboratory for researchers, practitioners, and industry professionals to facilitate experimental, computational, and technology transfer aspects of the MAST system, and provide training opportunities for outside researchers.