Evaluation the Seismic Retrofitting Methods of the Reinforced Concrete Frames
Seismic design did not used to be considered in pre-building codes. Consequently, existing old buildings do not have a proper lateral resistant structural system. Due to the historical value of some of these buildings, the economic cost of their demolition and reconstruction and their location in a dangerous seismic zone, many researches have been carried out to retrofit it, where several retrofitting techniques for mitigation seismic risk on structures have developed over the last three decades, going from more conventional techniques, such as bracing existing structures by adding new shear walls, steel bracing elements or jacketing the columns and beams to new and innovative technologies that involve energy dissipation systems, dampers and base isolation.
In Eurocode, the seismic retrofitting of existing building did not receive enough concern, for instance the behavior factor of the frames braced by Buckling Restrained Bracing is not mentioned, where bracing the frames with BRB is an effective and innovative way to improve the seismic capacity of structures.
These retrofit techniques are intended to reduce the overall seismic drift demand on the structure, while also enhancing its lateral load resistance, besides adding members, other techniques can be used such as reducing the seismic demand induced on the structure and removing particular components.
Since every building has a unique situation in terms of its seismic zone, function, importance and structural system, generalization specific seismic retrofitting technique may not be effective from an economic point of view, therefore four techniques of enhancing seismic capacity of an existing reinforced concrete building have been evaluated in this paper with changing different parameters of seismic zone. None linear Static Analysis (Push Over) has been implemented in order to obtain capacity curves, then seismic evaluation of the building's behavior has been carried out based on Equivalent Linearization Method in FEMA-440, by using ETABS software to estimate the effectiveness and eligibility of the implemented rehabilitation technique. First technique is strengthening the columns by jacketing and providing a cage of longitudinal and lateral tie reinforcement around the column and casting a concrete ring. Second one is mass reduction intention to modify the dynamic response of the structure. Third technique is bracing the R.C frames by conventional steel braces. Fourth one is Bracing by Buckling Restrained Bracing.
Szerkezet-építőmérnök mesterszak (MSc)