Since regular building inspection is required for buildings aged over 30 years under Mandatory Building Inspection Scheme, time and cost become important considerations when performing building inspection. Passive infrared thermography (IRT) is a building inspection technique accredited by the Hong Kong Laboratory Accreditation Scheme. Compared to traditional detection methods such as visual inspection and hammer tapping tests, IRT could be used to detect debonds in construction materials in a non-contact and non-destructive approach. Commonly used hammer tapping test requires scaffolding to perform the task, which increases the inspection cost. IRT inspection is a ground-based inspection which can be used to perform large-scale inspection. This project aims to develop a new methodology for imaging and diagnosis of external wall debond of tall building envelop by embedding quantitative IRT survey images in as built building information model (BIM). Thermograms of the building envelop will be processed to portrait the debond shapes and quantify debond sizes. Processed data will be transformed in a processable format and imported into BIM for health diagnosis.
The proposed workflow consists of 5 modules:Module
1 – Thermal Image CollectionModule
2 – Laser ScanningModule
3 – Image RegistrationModule
4 – Image ProcessingModule
5 – Data Conversion and Importing into BIM
The development of Module 1, 2 and 3 are completed. For Module 1 and 2, the requirements of data collection of both thermal images and laser scanning are determined. Data collected were then used in Module 3 for image registration of the target wall of the building. Module 4 and 5 are in progress, which are developed to identify suspected debonds on walls and then converted into BIM objects for cost estimation.
Preliminary Research Results
Module 1 Thermal data collected
Module 2 Point cloud collected
Module 3 Image registration
Module 4 Debond image after processing
Module 5 Debond shown in BIM model