Browsing by Author "Barbosa, André R."
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- Natural Hazards Challenges to Civil EngineeringPublication . Rodrigues, Hugo; Abrahamczyk, Lars; Barbosa, André R.; Shi, Haiyun; Ferreira, Tiago Miguel
- Post-earthquake field measurement-based system identification and finite element modeling of an 18-story masonry-infilled RC buildingPublication . Mohammed, Mohammed A.; Yu, Hanshun; Furtado, André; Barbosa, André R.; Moaveni, Babak; Varum, Humberto; Rodrigues, Hugo; Vila-Pouca, Nelson Saraiva; Wood, Richard L.This paper describes the system identification and finite element modeling of an 18-story unreinforced masonry infilled reinforced concrete building that was damaged following the 2015 M7.8 Gorkha Earthquake, Nepal, and subsequent aftershocks. The identification is performed using the ambient vibration data collected using broadband seismometers and accelerometers. The new apartment building was seismically designed using Indian Codes and Standards. At the time of the earthquake mainshock, its construction was complete as the building was being finalized for handover to the clients. Following the earthquake mainshock and aftershocks, most of the damage to the building was observed in the non-structural masonry infill walls, while minor damage was observed in the diaphragms and elevator core link beams on lower stories. The ambient vibration response of the damaged building was recorded using either: (1) fifteen accelerometers at different setups, or (2) three seismometers. The dynamic characteristics of interest are the modal parameters of the first few lateral and torsional vibration modes. The modal identification results from the two measurement systems are compared to provide insight into the uncertainty of the results. In addition, two finite element models of the structure are developed from the information provided in the design documentation of the building. The models are tuned to match the identified modal parameters and compared with each other. Special attention is placed on the stiffness of structural and non-structural elements.
- Seismic assessment of a school building in Nepal and analysis of retrofitting solutionsPublication . Rodrigues, Hugo; Furtado, André; Vila-Pouca, Nelson; Varum, Humberto; Barbosa, André R.Recent earthquakes highlighted the vulnerability of some infilled reinforced concrete structures due to the presence and distribution of the infill masonry walls. Buildings such as school buildings and residential buildings are typically not designed considering the contribution of the infill panels to the structure strength and stiffness, when these are subjected to earthquakes. The lack of consideration of the infill panel results in observed poor performance and structural collapses. This manuscript presents a numerical study of a school in Nepal, representative of those existent in the country. Non-linear numerical analyses were carried out to assess the seismic vulnerability in terms of peak inter-storey drifts. In addition, results will be presented and discussed in terms of peak inter-storey drift profiles and peak base shear. Results from a seismic vulnerability assessment of the pre-earthquake structure indicate that the presence of the infill panels in the original structures were responsible for the development a soft-storey mechanism, combined with torsion. Following the seismic vulnerability assessment, four different retrofit solutions were tested and compared with the results of the original structure to gain an understanding on the structural efficiency of each proposed solution. The retrofit solutions proposed revealed to be efficient and reduce the seismic vulnerability. The retrofit solution showing best results correspond to the ones in which reinforced concrete column jacketing was employed.
- Seismic performance of buildings in nepal after the gorkha earthquakePublication . Varum, Humberto; Dumaru, Rakesh; Furtado, André; Barbosa, André R.; Gautam, Dipendra; Rodrigues, HugoFollowing the strong earthquake of Gorkha, Nepal, on April 25, 2015, and a strong aftershock on May 12, a field reconnaissance of structural damage and structural collapses was performed around the affected areas, particularly in the region around the capital Kathmandu. The main goal was to develop detailed descriptions of the seismic performance of the Nepalese building stock. To achieve this goal, the field reconnaissance survey was carried out after the two main seismic events. In this chapter, a summary of the survey is provided, focusing on both recent reinforced concrete (RC) buildings and older substandard constructions. In addition, detailed descriptions of the observed damage to urban masonry building stock and rural vernacular constructions are provided. This chapter presents evidence from the field that justifies the observed seismic performance and enables the depiction of damage modes, which could be insightful regarding future efforts to develop earthquake-resistant constructions and strategies to improve the seismic behavior around the world.