Seismic performance of full-scale fire-exposed reinforced concrete columns produced by recycled concrete aggregate

Considering the ever-increasing industrialization, efficient use of limited natural resources has raised the issue of effective use of renewable energy. Even from the perspective of structural engineering, the demolition of structures due to earthquakes, urban transformation etc. results in waste materials, imposed on the economy. This sort of waste was reported as 170 million tons in United States of America (US) in 2003 [Cree et al, 2013]. and 17.3 million tons in 2008 in Canada [Canada Ministry of Industry, 2008]. In Turkey, for the next 20 years, approximately 6.5 million apartments are planned to be demolished within the scope of Urban Transformation Law (06/05/2012 - 6306). At the end of this process, it is assumed that approximately 500 million tons of debris [www.csb.gov.tr] will emerge. Planning for waste management becomes an important national policy, aiming to convert the waste materials as in input to create value-added products for the local economy, without creating a risk to the environment and human health. In recent years, developed countries such as US, Japan and the European Union, promote research on the use of concrete production with demolition waste, based on the theme of sustainability and reducing the carbon footprint of building materials. Therefore, in the next few years, the use of recycled waste in the construction of new buildings will be useful to ensure the economic and environmental sustainability. The waste management in Turkey is among the environmental protection policies, with increasing importance. In the scope of the project "The Assessment of Building and Demolition Waste", it has been aimed to eliminate environmental problems that will result from construction and demolition waste, contribution to the limited waste storage problems, and conversion of the waste to an economical benefit [Official Gazette, 12.01.2013-28586]. Studies on utilization of Recycled Aggregates (GDA) from demolition waste in new constructions led to the development of standards on this subject [EN 1262, BS 8500-2, DIN 4226-100]. In literature, there are studies demonstrating that the performances of reinforced concrete members constructed with GDA and DA are similar. However, it is also important to ensure the sustainability of GDA usage in concrete. During the service life of a structure, there might be risks such as, earthquake and fire. The number of structural fires between 2010 and 2015 was reported as 60.000 by Istanbul Metropolitan Municipality Fire Department. A similar situation is observed in many countries in the world [Hall, 2001]. In the majority of these fires, it is known that structural damage may be observed depending on the deterioration and thermal expansion of the materials such as concrete and steel rebar of the reinforced concrete structural elements, thereby adversely affecting the seismic performance of the structures. Research on post-fire performance of GDA which may risk the life of the residents and the fire safety of the structures is very limited. Turkey is located on one of the world's most active faults, and thus at high risk of earthquakes and fires caused by earthquakes. Therefore, for the life safety of the residents, who are living at the structures incorporating GDA, after fire, damage assessment must be immediately carried out by experts, the residual performance of the structure must be obtained and decisions should be given whether to repair, strengthen or demolish the entire structure. The purpose of the thesis, which has been the subject of very limited research in literature, is to investigate the post fire seismic behavior of reinforced concrete columns, constructed using GDA, by experimental techniques, and to contribute to the identification of the safest and the most economical process (repair, strengthen or reconstruct the structure) after fire.