Retrofitting of RCC Beams Using Steel Plates

Many of the building structure or any reinforcement concrete structure (super structure) damaged due to the extra load or frequent earthquakes. Retrofitting is used for small cracks and small damage of beams, columns, slabs and other RCC structures. Retrofitting prevent the complete replacement for existing structure using external materials. Mild steel plates with connection (bolt, rivet, welding) use in retrofitting, plates use 1,2and 3 layer in all face of beams The earthquake is serious problem for any structure. The building damages due to ground motion of soil by earthquake, settlement of foundation, improper maintenance, concrete related problems, increase loads at structure etc. The cost of complete replacement of building very high and if the building is historical reconstruction is not possible solution in this case we used retrofitting. For retrofitting design three beams. Cross section dimensions of beams are 100 mm ×150 mm. The total length of each beam is 1800 mm. Using M-25 grade of concrete. The mix ratio of M-25 is 1:1.4:2.95 of cement coarse sand, and coarse aggregate. The ratio of 20 mm and 10 mm coarse aggregates 60:40. The water ratio is 5.417 L for a beam. Fe-500, 2 numbers of 10 mm Ø steel bar provided in tension zone and 2 numbers 8 mm Ø bar in compression zone and also used Fe-415, 6 mm strips bar according to IS-456-2000. The strips bar provided 100 c/c in beams. The beams cast in wooden cost mould. The cast beams curing 28 days. The all beams tested in UTM applied point load. The load is applied until beam failure. After crack generated load from the specimen. Calculate the load and deflection and plot the graphs for each beam. Then used 12 mm thickness steel plate and 14 mm Ø bolts connection for retrofitting. In first retrofitting used one steel plate at bottom side and one plate at top of beam. In second retrofitting used two steel plates at bottom side and two plates at top of beam. In third retrofitting used one steel plate at front side and one plate at back side of beam no plates use at top and bottom side of beam. After retrofitting tested in UTM point load applied. Plot the graph between load and deflection.