Development Of Networked Structural Laboratories

In the field of Earthquake Engineering, structural experiments are still important means for understanding behaviors of structures and their components. Due to the complexity of earthquake mechanism and the highly nonlinear performance of structures under extreme earthquake loading, experimental research has been a direct and effective way to study seismic performance of structures. As the scale and complexity of modern engineering structures increase, existing structural laboratories, even those large-scale ones, are facing increasing difficulties to satisfy various types of demands of experiments with their limited resources. The rapid development of internet technology provides a new opportunity. The mechanics of communication based on network can apply not only the function of data communication and sharing, but also real-time control and feedback among distributed laboratories.With the rapid development of internet technology, a networked structural laboratory is established through real-time control and feedback via network to connect distributed laboratories aiming at more efficient sharing of the resources and advance capability. Sponsored by the National Natural Science Foundation under the National Key Project"The modern method and system for remote pseudo dynamic testing of structures under earthquake simulation"(50338020) and"Real-time hybrid testing method and technology of dynamic damage on large-scale building and bridge"(90715036), some studies on the method for remotely collaborative hybrid dynamic testing of substructures and structural elements via network have been carried out. The main research achievements are summarized as followings:1. The concept of networked structural laboratory is further advanced and the framework of the networked structural laboratory system NetSLab is built. The system is composed of a relatively independent network communication platform and various application programs developed based on this network communication platform. Application programs could provide the interface with various different control systems of testing facility.2. From the remote testing point of view, a network communication platform NetSLab which is capable of transferring control and feedback data and signals among remotely located structural testing laboratories connected by Internet and facilitating data communication through firewall and network address translation is further developed. The communication platform NetSLab can apply powerful communication capacity. Dynamic unified data packet and generalized data communication agency are introduced to make data communication in a testing procedure become clear and simple, management and maintenance convenient, and further development by users.3. Aiming at the complicated network and commonly deployed firewalls in domestic, two communication frames are proposed for remotely collaborative tests to make sure NetSLab could apply widely. An on-line issue system is built to make testing process and result share with more researchers in the world via Web. The programming method based on NetSLab is introduced as a sample to remotely testing programmer.4. A framework based on the client/server concept is proposed for developing robust standardized application programs for remotely collaborative testing of large-scale structure systems. All the application programs are composed of four modules, named as control center, physical tester, virtual tester, and remote observer. ControlCtr plays as the server of the platform. It organizes the testing procedure, controls the testing progress and data communication among all participants, and stores or publishes the testing results. PhysicalTester operates the actual testing equipment to generate testing results. VirtualTester uses computation to provide restoring force of substructures instead of physical equipments. Observer monitors the process and shares the testing results without any interference of the test processing. It can join or quit a test at any time during testing.5. Aiming at different structural models, several remotely collaborative hybrid dynamic testing programs are developed with Visual Basic program language, such as SDOF-module for remotely collaborative testing of single story structures, MDOF-module for multiple degree of freedom system of shear type frames and Torsion-module for remotely collaborative testing considering torsional effects. Successful applications of several structural experiments among Hunan University, Tsinghua University, Harbin Institute of Technology and University of Southern California have verified the validity and efficiency of application programs and the collaborative capability of NetSLab.6. The communication interface between NetSLab and MTS system which is widely used in structural testing is realized by many ways, such as developing standard ActiveX control through Dynamic Link Library and making use of acquisition board control.7. Aiming at the lack of analysis function in networked structural laboratory system NetSLab, the communication interface between NetSLab and the finite element software OpenSees developed by University of California at Berkeley has realized to develop a hybrid simulation system using substructure technology. Several validated simulation tests have been conducted.In summary, the objective of this research work is to build an open and shared networked testing system which would allow for more collaborative hybrid tests through linking exiting facilities via Intranet or Internet and corresponding methods are proposed.