Evaluation and comparison of strengthening methods to deliver a safe, efficient and economical solution

The challenges posed in the choice selection of strengthening methods to strengthen old existing buildings which might be exposed to external loads, poor concrete grade, poor construction and review in codes has been of concern recently. Through the various guidelines for building evaluation, strengthening and with innovative structural codes for design, building assessment and strengthening are carried out using newly developed technologies worldwide. Basically, there are two major categories of strengthening; local and global methods. Local method is focused at the element level on structural members which are deficient and need improvement to perform better. This method includes adding composites, concrete or steel on the surface of a structural member. They are all effective but also have their disadvantages, while the global method acts on the structural level. Its application will lead to obtaining the behavior of the entire structure. This method consists of addition of steel bracings, shear walls and infill walls. These methods equally have their effectiveness and disadvantages. In this study, strengthening methods were discussed considering its advantages and disadvantages where some application procedures were as well highlighted. The procedures for building assessment were also discussed. A coded decision selection program for strengthening methods were constructed which will help for selecting the best option from strengthening methods. Coded strengthening programs for fiber reinforced polymer (FRP) were also prepared and it gave the same result with the referenced FRP strengthening. Two case studies were carried out in other to compare the result with the coded decision selection tool. The cases studies were modeled and designed with structural software such as STA4CAD, CSi COL and Engissol structural software. The selection tool and the case studies gave the same result for the strengthening option. Both have shown that shear wall strengthening is the best option for strengthening the two investigated buildings. The economic evaluation of the materials used in different strengthening method studied, has shown that, shear wall is the least in the cost of strengthening. Therefore, shear wall strengthening method is cheaper, efficient and has significantly contributed to the overall strengthening and improvement of the performance of the considered building. Keywords: Strengthening, Performance, Global Strategy, Local Strategy, Ductility.