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“...On, K1S 5B6 Canada, Jeffrey. Erochko@carlet on. ca
c Department of Civil and Env. Engineering, Princeton University, E-208 E-Quad Princeton, NJ 08544, USA, rkn2@princeton.edu, imorris@princeton. edu
d Carleton Immersive Media Studio (CIMS), 1125 Colonel by drive, Ottawa, On, K1S 5B6 Canada, Mario.santana@carleton.ca eNepal Engineering College fBhaktapur Municipality gUNESCO Kathmandu Office h Khwopa Engineering College ‘National Society of Earthquake Technology
COMMISSION II
KEYWORDS: IT Documentation, Risk Preparedness, Nepal, Built Heritage, Natural Hazards, Capacity-Building, Digital Workflows for Heritage Conservation, 3D Imaging, Georadar, Photogrammetry, Electronic Distance Measurements (EDM), Computer-Aided Drawing.
ABSTRACT:
On 25 April 2015, the Gorkha earthquake of magnitude 7.8, severely damaged the cultural heritage sites of Nepal. In particular, the seven monument zones of the Kathmandu Valley World Heritage Site suffered extensive damage. Out of 195 surveyed monuments, 38...”
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“...the Conservation and Restoration of Monuments and Sites (The Venice Charter, 1964) in Article 16 states “In all works of preservation, restoration or excavation, there should always be precise documentation in the form of analytical and critical reports, illustrated with drawings and photographs. Every stage of the work of clearing, consolidation, rearrangement, and integration, as well as technical and formal features identified during the course of the work, should be included. This record should be placed in archives of a public institution and made available to research workers.”
In the case of the Kathmandu Valley, recording and documentation of the cultural heritage are as important as any other phase of conservation, from the repair, to alteration, to intervention work. Without documentation, important existing character-defining elements of the structures, in both a visual and structural sense, may be lost during restoration. It is particularly important to document these buildings...”
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“...collapsed monuments.
In general, the workflow for carrying out this research project is divided into two parts as described previously: documentation and structural investigation. Many of these workflows were also applied to the evaluations of the other sites.
For recording and documentation of Nyatapola Temple, multiple digital tools were used. Recent developments in computer and information technologies have resulted in a wider range of options to document heritage structures with high precision.
The digital workflow used for field work was as follows:
• Establish a local coordinate system oriented to Azimuth using the Total Station, measuring control points (Targets)
• Using 3D Scanning and Photogrammetry to record the state of conservation of the outer surface of the sites
• Panoramic Photography for referential purposes
• Incorporation of subsurface documentation from georadar survey into digital models
Figure 2. Nyatapola and Bhairavnath temples scan Point Cloud.
Figure 3. Accuracy of the...”
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“...in the doorway on all four-side wall also identified. High-quality orthophotos are generated from the close-range laser scanning and photogrammetric models. These orthophotos were used for mapping existing cracks in the wall (figure 12). Mapping of these cracks will then be introduced in the finite element modeling for assessing the existing performance of structure in future.
Figure 12. Mapping of existing cracks in structural wall
3.2.3 Geo- Radar Investigation
In addition to the surface documentation using laser scanning and photogrammetry, non-destructive techniques were used to investigate the inner composition of structural elements. For this purpose, geo-radar survey was conducted on the masonry walls (with a 900 MHz antenna) and plinth (with a 270 MHz antenna) of the Nyatapola temple. Georadar is a travel time tomography method that works by recording electromagnetic waves which are reflected at dielectric interfaces (different materials). Georadar allows the identification of morphology...”
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“...be used for further structural investigation of the seismic response of the temple.
Following the collection of geometric, morphological, damage, and other information on structural elements, a finite element analysis or combined discrete element analysis will be conducted to evaluate the seismic behaviour of the Nyatapola Temple in a separate study.
4. SCOPE OF ADDITIONAL WORK
In addition to the documentation and evaluation of Nyatapola Temple, the Carleton University - Princeton University team worked in collaboration with local Nepali colleagues to perform the following additional documentation and analysis work:
At Bhaktapur Durbar Square:
• Vatsala Temple - Georadar evaluation of the plinth structure to confirm excavation results, determine inner sanctum construction, and use this information to validate survey parameters (velocity and dielectric constant) and construction material reflections.
• Big Bell - Georadar evaluation of the supporting structure and photogrammetry.
At Dattatreya...”
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