Work Package 3

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Work Package 3

This WP explores the use of numerical and analytical modelling tools to study the seismic behaviour and dynamic capacity of masonry structures. Tools like rocking dynamics or macro-element modelling which are computationally efficient are to be validated on the experimental results (WP2) and tested under varying conditions (WP1).

Modelling masonry as a discontinuous medium is difficult due to the highly nonlinear material behaviour, formation of discontinuities after cracking, and occurrence of large displacements. Nonlinear behaviour can be considered, but dynamic analysis requires a large computational effort, meaning that simplified models are needed.

Rocking analysis, based on formation of macro-blocks from the remaining structure, is a possible approach to assess out-of-plane response. This approach is very sensitive to the seismic signal and boundary conditions, and has been validated with reference to a few tests. The reproducibility of the response of a single test is currently impossible for random input. In fact, the problem can only be treated using probabilistic theory. WP3a will serve, partly, to develop an enlarged probabilistic approach, to be validated against the large number of rocking tests to be performed on the shaking table.

Macro-element models have also been disseminated as an alternative to detailed models, since the number of degrees of freedom is largely reduced. Macro-element approaches have been developed to simulate the 3D response of masonry structures. These approaches were verified against a few tests, but will be now fully validated against the planned shaking table tests (WP3b), which will also enable calibration of out-of-plane backbone models (WP3c).

Aiming at the performance-based analytical assessment of heritage buildings to support intervention design, fragility analysis is to be performed (WP3d), based on incremental dynamic analysis (IDA) and using representative accelerograms obtained from the stochastic analysis in WP1b. Convolution of the probability density functions defined from experimental results, which is a novel procedure, and the displacement demand by IDA will provide the fragility curves that will also serve as input for WP4d.