The consultancy fee for structural design changes of reinforced concrete buildings in Oman

Abstract

Design changes in reinforced concrete buildings have for long time been a topic of prolonged arguments and frequent disputes due to their common phenomena of incidents in the construction industry. Although design changes in many cases are essential, clients, consulting engineers and contractors all have become increasingly worried about the negative parts that are associated with them. Design changes do not only affect the reliability of design but also increase the possibility of contractual disputes due to unpredictable delay and cost overrun on the original scope of work. While the cost of modifying the construction scopes is well defined in normal contract documents, but the fee of engineering changes is yet to receive more attention. Therefore this research has been developed with the aim to investigate such issues and to develop an alternative approach in evaluating the fee of altering the original scope of design work. Extensive study was performed at the initial stage of this research work in term of interviews, case studies and questionnaire survey in order to identify the sources, causes and impacts of design changes on reinforced concrete buildings as well as to establish corrective actions and preventive measures to minimise the avoidable ones. Frequency analysis and non-parametric statistical technique employed in this research to analyse the qualitative and quantitative data. It was found that engineering design changes are common in the industry and, in many cases, lead to excessive claims and disputes due to lack of appropriate and practical methods to assess their associated fee. Although there are various methods being used for assessing the fee of design changes, this study identified their limitations for practical use. Consequently, an alternative method for assessing the fee of the structural design changes has been developed in this research based on designing various type and complexity of low rise RC buildings. The developed method has been verified by a panel of experts by means of questionnaire survey and found to be practical, suitable and effective. Set of guidelines for improving consultancy design documents with respect to design changes and another set of guidelines for managing their claims have been also developed. These guidelines have been validated by panel of experts using Delphi technique. The result of the validation process provides encouragement to recommend the guidelines for practical implementation