Issue 45

F. Brandão et alii, Frattura ed Integrità Strutturale, 45 (2018) 14-32; DOI: 10.3221/IGF-ESIS.45.02 29 Comparison between the results obtained by Earthquake 1 and Earthquake 2 During the application of Earthquake 1 and Earthquake 2 to the Nossa Senhora das Dores Chruch, directional displace- ments in the X, Y and Z directions and principal stresses are obtained, as well as the peaks of stress during the 30 s of seismic loading. Because the two earthquakes have different magnitude, different frequency content, different peak ground acceleration and because the peaks are also different between the three components of each earthquake, the re- sults obtained in the two analyzes show significant differences. In Fig. 22.(a) the maximum value of the directional dis- placements obtained in the two analyzes is reported while Fig. 22.(b) reports and compares the maximum and minimum principal stresses obtained during the two time-histories. The Earthquake 2, as expected, was the one that caused greater displacements and higher stresses. It can be interesting, anyway, to observe that in both cases the biggest displacements over the time-histories are obtained in the X direction (the transversal one), thus confirming the potential overturning of the main nave of the church. C ONCLUSIONS he paper investigated the seismic behavior of Nossa Senhora das Dores Church, an important heritage construc- tion within the historic city center of Sobral (Ceará State, Brazil). The work aims to contribute to the acquisition of knowledge about seismic the behavior of Brazilian heritage constructions. First, based on the available infor- mation, a refined 3D numerical model of the church was build. The elastic properties of the model, after a preliminary es- timation, were calibrated according to the results of an experimental investigation (environmental vibration testing aimed to evaluate the main frequency of the structure). Subsequently, the seismic behavior of this structure was assessed by per- forming linear time-history analyses according to two seismic scenarios: two natural records were considered. The re- sponse of the church under the two seismic events was analyzed in the linear field, this means that the obtained results do not account for the cracking and the crushing phenomena that may be activated during the seismic loadings. Consequent- ly, a more refined non-linear time-history analysis should be performed after a refined experimental investigation aimed at evaluating the properties of the materials needed to implement the non-linear material laws. Notwithstanding, the prelimi- nary results herein reported are able to highlight - even if from a qualitative point of view- the most significant elements that characterize the behavior of the structure during the earthquake identifying potential seismic vulnerabilities and defi- ciencies. By the analysis of the results of the time-histories, it was found, for example, that the church behaves as a com- bination of independent macro-elements (i.e. without a box-behavior) with first and second mode potential failures. De- pending on the earthquake (its magnitude, its PGA and its frequency content), the overturning of the main facade, of the lateral and central walls and pounding between the lateral tower and the confining walls is expected. This suggests possible retrofitting solutions that can be proposed to improve seismic performance, structural safety and construction preserva- tion. A CKNOWLEDGMENTS he authors would like to acknowledge the National Historic and Artistic Heritage Institute (IPHAN), the Paróquia de Nossa Senhora da Conceição in Sobral and the Laboratório de Reabilitação e Durabilidade das Construções (LAREB) for all support and useful information for development of this work. Francisco Brandão acknowledges the State University of Vale do Acaraú by research fellowship. R EFERENCES [1] Roca, P., Cervera, M., Gariup, G. and Pelà, L. (2010). Structural Analysis of Masonry Historical Constructions. Classi- cal and Advanced Approaches. Archives of Computational Methods in Engineering, 17(3), pp. 299–325. DOI: 10.1007/s11831-010-9046-1. [2] Fioravanti, M. and Mecca, S. (2011). The safeguard of cultural heritage: A challenge from the past for the Europe of tomorrow. Florence: Firenze University Press. [3] Bowitz, E. and Ibenholt, K. (2009). Economic impacts of cultural heritage – research and perspectives. Journal of Cultural Heritage, 10(1), pp. 1–8. DOI: 10.1016/j.culher.2008.09.002. T T