3rd Croatian Conference on Earthquake Engineering 3CroCEE

There are many cases around the world where vertical extensions of existing buildings are favored as alternatives to the erection of new buildings, which would entail demolishing the old structure as well. Such solutions with vertical extensions have certain benefits, but the design characteristics of the base structures and their condition after years of service urge careful consideration of the joint between the new and old structural members and how it affects the global performance of the entire system. The risk to human lives, as well as environmental, economic, and social implications – including pollution and carbon emissions contributing to the greenhouse effect – serve as a strong motivation for researching these connections. This issue becomes especially critical in regions prone to frequent tectonic activity, where errors in the design and execution of additional floors on existing buildings are often observed. The errors observed on-site during the execution and design of additional floors on existing buildings are notable. This paper will discuss the research needs for improving the seismic behavior of the structural detailing and subsequent modeling for structural analysis of this connection between the vertically added floors and the base structure, focusing on the reinforced concrete frame structure solutions. The connection between the new floor and the old structure might not be rigid as is often treated in the design phase, and the behavior of the joint in response to dynamic forces might differ from what is projected thus the joint might not be adequately addressed from a seismic behavior perspective. The treatment of this issue will be discussed taking into consideration the conditions in the on-site execution and the provisions of Eurocodes standards, namely the EC2 part 4.
Keyword: Vertical extention, joint connection,seismic behaviour,on-site execution.