A System for Multi-Axial Subassemblage Testing (MAST)

小乔治·E·布朗。地震工程模拟网络(NEES)计划是美国国家科学基金会重大研究设备计划资助的一个项目。这项合作协议根据NEES计划，在明尼苏达大学双子城校区建立了NEES大规模实验室地震工程研究实验场。该大学将为结构地震工程实验设计、购买、建造、安装、调试和运行多轴组件测试(MAST)系统。该设备将于2004年或更早投入使用，并将作为国家共享的NEES设备场地进行管理，具有远程观测和远程操作能力，以在2014年前提供新的地震工程研究测试能力。这个NEES设备站点将通过大学的Abilene连接连接到NEES协作室，具有千兆位以太网能力。共享使用准入和培训将通过NEES联盟进行协调。该奖项是对提交给NSF 00-6计划征集项目“NEES：地震工程研究设备”的建议进行同行评审的结果。多轴组合测试(MAST)系统将大型结构试验与结构构件和系统的三维非线性分析联系起来，提供了一种模拟中、大型地震作用下建筑物和桥梁结构响应的综合方法。桅杆系统能够对大型结构件进行多轴循环和拟动力试验，例如部分梁柱框架体系、墙、桥梁和桥墩。桅杆系统由高性能执行器、顶部和底部反应面的十字头(大型钢焊接件)、带有六自由度(DOF)软件的数字控制器(控制系统)、液压分配系统和L形状的反力墙系统组成，为水平执行器提供横向负载阻力。桅杆系统使用六自由度控制器来定位顶部十字头，使用八个执行器(四对垂直和两对水平的正交执行器)，以直接和可重复的方式施加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，通过实时同时控制八个十字头执行器来定位十字头的位置。该系统不仅可以控制空间中一个点的位置，还可以控制空间中的一个平面。这一特点使得可以对结构进行双向控制，例如多开间组件或墙。它还允许应用纯平面平移，以及应用坡度来模拟倾覆(例如，多跨框架柱中的轴向荷载坡度或墙体摇摆)。利用该系统，可以对试验结构施加全六自由度加载条件，从而提供了一种新的大规模试验能力，将提高地震工程界对复杂破坏状态的了解。桅杆系统将设在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875,000美元的费用，用于改善实验室基础设施，以适应桅杆系统。明尼苏达大学将把MAST系统整合到其研究计划以及本科生和研究生课程中，为研究人员、从业者和行业专业人员实施MAST合作实验室，以促进MAST系统的实验、计算和技术转让，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.