Analysis On Applicable Conditions Of Variation Valuation Principles Under Multiple-impact Factors

Variations in construction are considered common during the project execution which varies in origins such as design change,on-site conditions change etc.It could be as consequence of Employer’s decision to rectify or improve the flaws and defects in design or Contractor’s proposal for design optimization.However,a number of variations have tremendous impacts on both cost and time schedule,which has already been the focus of dispute and attention of Employer and contractor.It emphasizes the importance of management on variation cost assessment.On the basis of analysis on the current application status of the three variation cost principles in China and other countries,the thesis points out the existing questions in actual applications,namely,the choice of three principles on the basis of presence of same or similar contract rates i.e.referring to the same rates set out in contract schedules;similar price rates or building new reasonable rates without considering the variation work characteristics or work conditions and extent of similarities of varied work to contract work.The thesis further analyzes the types,reasons and scopes of various factors affecting execution of variation works that are summarized into three categories consisting of time,technical workmanship and system,which transforms the factors to index analysis framework.With the introduction of AHP analysis model,a Tiered Decision Model on Variation Cost Principles is built to include Objective Level,Standard Level,Sub-standard Level and Plan Level,which is analyzed by any professional expert by assigning comparative weight to indexes with a number between 1 and 9 by comparing with one another to form comparison matrix.The indexes at the same level are compared to generate a weighting order.After the availability of all levels of indexes in sequential order,a general weight order will be generated to support the plan decision and choice.At the end,the model is applied to actual cases which achieve a result basically conforming to the real situation.The Analysis Model on Variation Cost Principles provides a mechanism to transform the decision process mainly built on the Employer or Engineer’s subjective judgment to a decision analysis built on procedural,systematic and multi-party participating mechanism,which establishes an objective standard to allow participation of multi-parties and provides a reference and useful tool able to reduce the disputes on variation cost valuation and claims.