Han K,Gwak J-Y,Golparvar-Fard M,Saidi K,Cheok G,Franaszek M,Lipman R
Vision-based field inspection of concrete reinforcing bars
Abstract: Concrete reinforcing bars should be accurately placed in the positions shown on the construction drawings, adequately tied and supported before concrete is placed. These elements should be further secured against displacements within the tolerances recommended by project specifications. Ensuring compliance with contract documents and the building code applicable to the project under construction requires photographic documentation and close visual examination by field inspectors. Although inspection procedures are repetitive for every jobsite, the manual inspection methods are time-consuming and non-systematic. Moreover, the current practice of field inspectors walking into rebar cages and footings for close assessments can be a potential safety hazard on jobsites and can damage the integrity of the structure. To minimize the challenges of the current practice, this paper proposes a computer vision-based method for field inspection. In the proposed method, a field inspector can carefully walk around a rebar cage and take a complete collection of images from the underlying structure. Using a vision-based 3D reconstruction pipeline of Structure-from-Motion and Multi-view Stereo algorithms, a dense 3D point cloud model will be generated. Using an algorithm that maps and generates a density histogram of points, the locations and configuration of the rebars are identified. Finally, the spacings between rebars are calculated for field inspection. Experimental results on data collection, analysis, and visualization components of the proposed rebar inspection method is presented. These results show the promise of applying this low-cost approach in practice.
Keywords: Rebar mapping,field inspection,vision-based 3D reconstruction,concrete placement
Full text: content.pdf (2,283,278 bytes) (available to registered users only)
Juergen Melzner, Jochen Hanff and Jochen Teizer
Pattern-Based Generation of 4D-Schedules for Robust Construction Management
Abstract: The creation of construction schedules is a time-consuming manual process. While project planning depends on many tasks and parameters, the quality of schedules highly relates on the engineers' experience and the access to reliable, historical project data. While knowledge applied from software can assist an engineer, the main shortcoming of current tools is the separation in generating building information and construction process models. Proposed is a knowledge-based system that automatically generates 4D-schedules based on building information models. Patterns are used to generate a process model for repetitive work flows, such as placing formwork, reinforcing, and concreting. Pattern-enriched attributes, i.e. the topology of the building structure, are automatically applied to objects in the model. Resource allocation, such as varying the performance factors or the amount of work crews, becomes possible. Such analysis can still be evaluated and exported in the format of traditional Gantt-diagrams or color-coded 4D-schedules and the construction process model can be used for detailed scheduling, construction time control, and time-based quantity evaluations. The developed approach was validated for the concreting work of a 12-story tall office building under construction. Preliminary results indicate gains in accuracy and efficiency of the developed approach compared to the traditional scheduling process.
Keywords: 4D, Construction Schedules, Building Information Modelling (BIM), Simulation
Full text: content.pdf (3,844,450 bytes) (available to registered users only)
Sakamoto, S., Takeno, M. and Shirato, A.
Development of Reinforcing-bar Fabricating Robot
Full text: content.pdf (3,518,234 bytes) (available to registered users only)
Salim M D
A cad-integrated process planning system for the design,
fabrication and assembly of reinforcing steel
Abstract: The fast advancement of computer technology has greatly benefited the industry in general. In particular
manufacturing has embraced the benefits of computers to control production processes which is directly
interfaced with computer aided design and drafting software. The construction industry, on the other
hand, has yet to realii the full spectrum of potential gains that can be derived from the use of computer.
However, the construction industry is currently experiencing a marked increase in the introduction of
automated methods to improve productivity. One area where drastic improvements in productivity can
be expected through computer integrated system is the fabrication and assembly of reinforcing steel in
construction. This paper presents new concepts for feature-based design and process planning, a key
element of computer-integrated construction (CIC). The work discnssed in this paper includes the
establishment of feature based design within AutoCAD. It is integrated with a database and the LEVEL5
OBJECT software. AutoLISP programs were written to support the feature based detail design of an
object. LEVEL5 OBJECT combines expert system technologies and object-oriented programming.
Finally, the paper presents the CAD-integrated process planning system linked with a reinforcing steel
fabrication facility for automated fabrication operations.
Full text: content.pdf ( bytes) (available to registered users only)