RETROFITTING OF THE MAIN BUILDING OF I.I.T., ROORKEE

Abstract

The present study deals with the retrofitting of the main building of IIT, Roorkee which lies in zone IV. The building has Roman style architecture with large columns. The building is in brick masonry with cavity wall construction having two brick panels and the cavity is filled with the soil. It has a dome on the front of the building. In this study, the safety evaluation of walls, columns and dome have been carried out for the earthquake forces as per the code of practice IS: 1893 (Draft Code). The safety of walls has been evaluated by considering the respective tributary areas. The forces in different walls and columns have been distributed in the ratio of stiffness. The analysis for the dome has been carried out using STAAD III software, modelling it as a lumped mass system. The safety of walls is checked in out-of-plane bending, in-plane shear and compression. The safety of columns is checked in compression, in bending due to lateral loads and the combined effect of compression and bending. The safety of dome is also checked in compression, in bending due to lateral loads and the combined effect of compression and bending. The results obtained after the analysis are compared with the permissible value of compressive stress and shear stress. This comparison shows that the walls are unsafe in out-of-plane bending. Columns and dome are safe for earthquake loads. Two alternatives have been described for retrofitting of the walls: (i) application of welded wire mesh, and (ii) anchoring of the two panels of wall. The diameter of the wire mesh and spacing of the anchors have been estimated for this purpose. The columns have strengthened and their ductility improved by providing steel reinforcement. Retrofitting of masonry arches has also been suggested in the from of tie rods. Another alternative to this is I - section at the top of arches. Integrity of the building has also been improved by prestressing.