Currently, commercial engineering quantity calculation software like Guanglian Da and Swell can only calculate quantities for model entities that have been created within the model. They are unable to account for non-entity projects that have not been modeled, such as plastering on beams, columns, and other components. While thin walls can sometimes substitute for plaster layers, there is a lack of association between components. This results in missing items during quantity calculations and prevents accurate identification of omitted items. Consequently, manual inspection of the engineering quantity calculation process is required item by item. This manual approach consumes significant time and effort from cost budgeting personnel, failing to improve the efficiency of quantity calculation and cost estimation. It also undermines the practicality of fully automated quantity calculation functions.
To address this issue, a semi-automatic engineering quantity calculation scheme based on the Revit model is proposed. The project is divided into various work tasks following the Work Breakdown Structure (WBS). Required resources for each task are manually configured and linked to the related components. The system then automatically extracts and calculates quantities and costs based on these configured resources.
Although this approach may increase the time required for quantity calculations to some extent, the entire process is conducted under manual supervision. This provides clear insight into the overall quantity calculation results and highlights any missed items, avoiding loss of control during the quantity calculation and cost budgeting process. It also eliminates the need for tedious manual checking for omissions.
The quantity calculation scheme for solid models extracts geometric attribute parameters—such as length, width, height, area, and volume—from Revit model components. Using calculation rules defined in the program, it computes quantities and costs. For components whose quantities cannot be directly or conveniently extracted from Revit, the method extracts geometric data from the attached solid model components. It then accurately calculates their quantities by applying system-defined calculation schemes. This enables the Revit-based engineering project planning system to work effectively even with incomplete models. For example, this method applies to plastering layers on components and steel reinforcement within concrete components, as described below.
(1) Component Plastering Layer
Revit does not support creating plaster layers directly on model components, making it impossible to extract plaster quantities from the model. However, plaster quantities significantly impact calculation results. Although some Revit plugins exist to generate plaster layers on components, they are time-consuming and cannot create plaster layers for all parts. This reduces the accuracy of quantity calculations and cost estimates.
In this system, geometric information about the components attached to plaster layers is automatically retrieved via the API. Calculation rules configured within the system then accurately determine plaster quantities. For example, consider a concrete rectangular beam with a length of 5700 mm and a cross-sectional size of 400 mm by 700 mm. The plaster quantity can be calculated using the formula: 5.7 × (0.4 + 0.7) × 2 = 12.54 m², representing the plastering area on the beam.
(2) Steel Reinforcement Bars
Revit allows the creation of concrete component reinforcement models using reinforcement system families or custom families to select appropriate reinforcement types. The quantity of steel reinforcement can be calculated based on the length and density of the steel reinforcement model. However, this method requires a high level of modeling detail.
The approach presented here does not extract steel reinforcement quantities directly from Revit. Instead, after obtaining geometric information of concrete components from Revit, the reinforcement ratio is input into the system. The system then calculates the steel reinforcement quantity based on the geometric parameters and the reinforcement ratio of the components.
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