Considerations in Vertical Extension of Reinforced Concrete Structures

Abstract

ABSTRACT There has been an increasing tendency to undertake vertical extensions in a number of structures being renovated or improved. This development usually involves change and improvement of function of the structure. However vertical extension has been complicated by the fact that most of the original plans of these structures are missing. Moreover most of these were designed using older codes based on elastic analysis such as CP114. This paper explains how the buildings designed using the older codes based on elastic analysis have reserve strengths when extensions designed based on limit state design codes such as BS8110 and Eurocode 2 are added. It sets out considerations that have to be taken into account. These include: determining the strength of existing structures and of the soil. Investigating the capability of the existing structure to carry increased load and effecting the modification in the slabs, beams, columns and foundation design. The composite action of the new concrete that is added onto the old concrete is also considered.