Structural condition assessment and retrofitting of Shital Niwas building (presidential palace)

Abstract

Shital Niwas, presently serving as the “Office of the President of Nepal”, is a 96-year-old palace located at Maharajgunj, Kathmandu. It is a Rana-era building mixing Malla architecture with European Palladian (also called neoclassical) style building with a central courtyard system. It suffered damage during 2015 Gorkha earthquake. The block surrounding the northern courtyard was severely damaged, so after the earthquake it was demolished. Significant part of the building that stands is still operational and accommodates critical functions, thus its seismic safety is important. Initially, damage assessment was conducted and damage grade was assigned as per EMS-98 classification. Low strength of mud mortar masonry, heavy weight of the walls and floors, presence of long unsupported walls under flexible diaphragms, high ratio of openings, and absence of earthquake-resistant features are some of the seismic deficiencies of present building. To reduce seismic risk, existing materials were characterized, the present performance of the building was evaluated and deficiencies were identified. Based on the deficiencies, different intervention options were investigated, and finally retrofitting with steel plates and carbon fiber reinforced polymer (CFRP) bands were selected after detailed analysis and design.