A study on the horizontal expansion of existing reinforced concrete buildings
The great goal of this study was to investigate the possibility of extending horizontally the existing reinforced concrete buildings without destruction. The present study focuses on techniques, necessary materials and adequate equipment to be used for horizontally extending a building without being destructed. The investigation was undertaken on “L- Shape” existing reinforced concrete building to be extended for getting its structural design data, the building is 395m2. The additional part is 142.59m2, and as result the whole building is 537.59m2. It was found that non-destructive tests should be carried out in order to know present life of building to be extended which leads structure engineer to know how to design the additional part. Where new concrete is to be applied to an existing concrete surface, Surface roughening prior to cast new concrete against existing should be done to provide and increase adhesion between both two surfaces. It has been found that sika product as structural bonding agent should be applied between old and new concrete surfaces during casting of slabs and beams. The surface where Sika product is to be applied requires to be sound, dry, clean and free from ice, standing water, grease and oils; any coatings and all loosely adhering particles should be removed to achieve open textured surface. It has been found that there are two possibilities leading Structure Engineer how to treat columns located on side connecting old part and new part of building: (1) when beams and slab of new part have been designed as cantilevers, these columns will remain as they are. (2) When beams and slab of new part have been designed as having end supports, these columns must be strengthened in order to support both existing and new loads. The easy method for strengthening column is enlarging its section (i.e jacketing). It has been found that foundations of columns also need to be strengthened in the case of applying additional loads, widening and strengthening of existing foundations have been carried out by constructing a concrete jacket to the existing footings. In this project, the architectural and structural design have been done in order to ensure the avail of serviceability of additional part and its safeness for occupancy. It is believed that the horizontal extension of the existing building will increase the number of occupancies, resulting in proper land use in Rwanda.
Key words: building, concrete, columns, structural bonding,