Manual quantity takeoff using two-dimensional (2D) drawings and personal knowledge is error-prone and time-consuming. Theoretically, quantity can be automatically calculated from building information model more quickly and reliably by extracting geometric data and semantic attributes of building elements. Specific construction classification systems embedded in mainstream modeling software for building information modeling (BIM) make it difficult for countries adopting different systems to calculate quantity directly. This paper proposes a BIM-based quantity takeoff code mapping (BQTCM) method to solve the above issue, and develops a quantity takeoff code mapping plug-in (QTCMP) on a BIM modeling software based on the proposed BQTCM method to obtain an accurate bill of quantities directly and efficiently. Moreover, by conducting a statistical analysis and examining a case study, this paper verifies the accuracy and efficiency of quantity takeoff attained from the proposed BQTCM method and QTCMP.
<p>In traditional three-dimensional (3D) printing, large-size 3D print machines, restricted print sizes of structural components and unstable printing quality limit its application in construction engineering. This paper proposes a mobile 3D printing technique for construction engineering. In this technique, a mobile 3D printing construction robot (M3DPC-Rob) is developed that takes advantage of a movable platform and flexible mechanical arm to cover the printing range of ordinary residential buildings. In order to locate the robot accurately in outdoor environments, an outdoor positioning and navigation method based on reflective columns is proposed. Furthermore, a quality control process is developed and modified to improve the quality of the printed line width. The results of a case study reveal that the outdoor navigation and printing quality control techniques of M3DPC- Rob show sufficient and steady accuracy that meet the requirements of construction engineering.</p>
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