Research On BIM-based Direct Cost Control For The Contractor In The Construction Stage

Under the current situation of the construction industry,it is unwise to keep the original extensive management mode for most contractors in China.However,BIM(Building Information Modeling)which is being highly promoted by Chinese government provides favorable technical support for construction enterprises to operate better cost management.This paper focused on the contractor's direct cost control during the construction stage and tried to utilize BIM to improve the essential work of cost control that is keeping the expense within a reasonable range by taking correction measures according to causes of cost variances between the planned cost and the actual cost.Firstly,deficiencies existing in contractors' cost control were analyzed based on some researches and practical cases,and the main deficiencies includes unspecific cost plan,being quite difficult to collect actual cost data and loss of information to get accurate causes of cost variances;secondly,according to practical application of BIM and some related papers,advantages of BIM in improving cost control were studied.It proved that BIM is able to integrate building information in multiple dimensions,improve the efficiency and accuracy of quantity take-off and offer a visual management platform;thirdly,combing with the superiorities of BIM,a BIM-based framework of direct cost control available for contractors in construction stage was proposed.The framework uses BIM in the four main stages(comparison,analysis,correction and check)of cost control to deal with existed problems.After that,implementation methods of the framework were studied.At first,it is suggested that the cost baseline should be divided into two groups(one is for resource and the other is for subdivisional work)so that the baseline is specific enough.And necessary information must be added while creating the BIM model to ensure needed data for calculating cost baseline be able to be extracted from the model.Then,collect actual cost data and make them related to BIM,and work out cost variances which show differences of cost baseline and actual cost.Cost variances is also divided into two groups(one is for resource and the other is for subdivisional work)to provide sufficient data for variances analysis.Next,with the help of variances causes,reasonable correction measures are taken and BIM is used for making correction work more efficient and updating cost baseline automatically due to BIM's visualization and parameterization.Finally,the proposed framework and its implementation methods proved to be practical by utilizing them in a project,also,they proved to be more capable of providing more sufficient data for cost correction than the traditional EV(Earned Value)method.In addition,in terms of making cost baseline,BIM application improves efficiency and accuracy of quantity take-off and cost accumulation,and it helps to provide a more instructive cost baseline than the traditional ways.