# Onsite Testing for Nonlinear Analysis of an Earthquake Damaged Historical Church in Italy
## 6 Conclusions  
A comprehensive study on the nonlinear seismic response of an historical masonry church was performed through a complex finite element model based on experimental measures. The results from the onsite testing (double flat jack test, video endoscopy and sonic tomography) and monitoring campaign (ambient vibration test) on the church of San Filippo Neri in Macerata were reported and implemented in an advanced numerical model. The ambient vibration test and the operational modal analyses successfully returned accurate information on the modal parameters of the church (natural frequency, modal shape vectors and modal damping of the first four modes of vibration), the result was used to refine the information on the different stiffnesses of the masonry by subdividing the model in several groups of elements, and to estimate the relevant influence of the soil-structure interaction through the semi-automated Douglas-Reid model updating method. The modal behavior of the updated numerical model is sufficiently close to the experimental values; it was not possible to further reduce the error by varying the most sensitive parameters. Additional effort is required to model other characteristics of the building (discontinuity due to the longitudinal crack, refinement on the mass distribution and flexible lateral constraints to model the influence of the lateral building). Static and dynamic nonlinear analyses were performed and compared to study the seismic behavior of the church. Both the analysis returned qualitative results in terms of capacity in agreement with the expected behavior and the complexity of the church. The quantitative outcome is sensitive to the dynamic behavior and choice of the control points. Once the qualitative behavior is established, the comparison of multiple control points becomes a fundamental aspect to take into consideration in the quantitative evaluation of the seismic capacity. The performed analyses prove the capability of the methodology that integrates onsite testing, ambient vibration testing with the sensitivity analysis and the model updating to tune up an advanced finite element model. The numerical simulation supported the intuitive detection of the critical locations, and it highlighted the relevance of local failure mechanisms over the global response of the systems. The methodology allows for the design of a minimal strengthening intervention to achieve a high level of safety compatible with both the need of protection and conservation of historical monuments. Refined numerical models updated by means of onsite experimental testing together with nonlinear analysis are capable to evaluate the present structural conditions, predict the behavior under severe events and propose accurate strengthening interventions that other simplified models and analysis are not able to achieve. The great efforts of this methodology are challenging the community thatstruggles to adopt onsite testing and dynamic identification in the model definition, as well as nonlinear analysis in the structural verifications of masonry constructions. Simpler tools and methods are commonly used in the professional practice; the effort is indeed less at the expense of the accuracy and the final interventions which often end up being invasive or, in worst cases, counter productive. This work intends to disseminate an appropriate scientific approach to conservation of historical masonry constructions and facilitate the interpretation of the results of nonlinear analysis. Supervision S.S. and C.B. ; methodology, S.S. and V.S. ; formal analysis, V.S. and C.S. ; investigation, V.S. and C.S. ; writing--original draft preparation, S.S. and V.S. ; writing--review and editing, S.S. and V.S. All authors have read and agreed to the published version of the manuscript. This research received no external funding. The authors are grateful to the Diocesi of Macerata and Da Gai Studio for the geometrical survey and the technical reports.