Report - PEER - University of California, Berkeley

Non-linear substructuring was recently applied at ELSA allowing the assessmentof the performance of a six-pier bridge to be made with physical testing of two piersand on-line simulation of the remaining piers (non-linear numerical models) and deck(linear numerical model). A schematic representation of the test set-up is shown inFig. 6a). The bridge was tested for three input motion intensities corresponding toprobabilities of exceedance of 50, 10 and 2%, in 75 years (tests: 0.4xNE, 1.0xNE and2.0xNE). Recorded values of the maximum top displacement of the piers are shownin Fig. 6b). Detailed description and analysis of the results can be found elsewhere(Pinto, 2004).5.3 Other Potential Applications of PSD Testing with SubstructuringSubstructuring in pseudo-dynamic testing offers a series of possibilities, which canreduce costs of the experimental set-up and give way to the simulation of earthquakeresponse of large-structures (long or tall) that would be impossible to accommodate ina laboratory (for example the case of bridges). Testing of isolation and dissipationdevices with the structure simulated numerically and testing of a base isolated system(structure and dissipation or isolation devices) with online testing of the structure andwith the devices tested apart from the structure have already been done at ELSA forbuildings and bridges. Another interesting field where substructuring can beconsidered is SSI. On-line numerical simulation of the soil or structure behaviourscan be achieved. There are also challenging objectives for geographically distributedPSD testing, continuous PSD testing and fast PSD testing (to cope with strain-raterequirements) and coupling of PSD and shaking table facilities.Need and relevance to performance based seismic design of some of the abovementionedpossibilities and features might seem debatable. However, it is importantto note that the tendency is to perform more reliable and accurate experiments and tomove from element/sub-assemblage to systems testing (physical and hybrid), whichencompasses the objectives of PBSD.6. CONCLUSIONSA series of tests performed at ELSA in support to the development and calibration ofthe Eurocodes and in support to the assessment and re-design of existing vulnerablestructures have been presented. Focus has been placed on the issue of the definition oftest protocols aiming at the assessment of the structure performance for differentlevels of the input motion. A performance-oriented test protocol would require severaltests for different levels of the input motion. However, this may be unrealistic becausesequential tests on the same structure would lead to unrealistic damage accumulation.A test protocol considering input motions corresponding to serviceability and lifesafetylimit-states with a subsequent test to derive ultimate capacity appears to be themost appropriate. It is underlined that a ‘serviceability test’ is indispensable tocalibrate loss functions required in performance and risk-based design and assessmentapproaches. Non-structural elements must be also included in the test models.291