Lightly Reinforced Concrete Wall Systems in India: Revisiting the Seismic Design Basis

Abstract

Indian construction industry, especially in the past few years, is evolving through a phase of transition towards modern innovative construction methods. Constraints in land utilization and challenges in the real estate industry resulted in finding ways for more effective space utilization leading to the change of focus from horizontally distributed to vertically distributed structures including tall buildings. Also, large-scale residential projects are being established involving mass affordable housing schemes. Under these circumstances, prominence is being given to the timely execution of projects and this marked the advent of innovative technologies in India. The use of tunnel form construction and aluminium formwork-based concrete construction systems in projects, especially residential buildings, has paved way for distributed monolithic reinforced concrete walls as the principal structural system. International codes have identified the benefits of using such systems under seismic actions with respect to the structural redundancy and overstrength achieved. These considerations have also been positively utilized by the codal provisions by allowing the design of these systems with less stringent detailing requirements and providing behaviour factors equivalent to ductile systems, or by reducing the seismic demand thus making the design of these systems more economic. Under mass affordable housing schemes, a reduction in the construction cost could achieve significant economic savings. In this context, this paper looks at the advent of new construction practices in India resulting in lightly reinforced monolithic distributed wall systems, the specific advantages of these systems under seismic actions and how international standards adequately take advantage of the structural redundancy and overstrength offered by these systems.