Comparison of cover meter and ground penetrating radar performance in structural health assessment: case studies

An essential step in the condition assessment of reinforced concrete structures and evaluation of the residual capacity is the determination of the arrangement and quantity of reinforcement as well as the geometry of the structural elements. The objective of this paper is to present the fundamentals in the application of two non-destructive methods, cover meter and ground penetrating radar, in the determination of the above structural features. A comparison of the two methods is presented and their capabilities, advantages and disadvantages are shown through nine case studies.

Formulation of Methodology for Structural Health Analysis and Monitoring of Marine Structures

The structural deterioration of marine structures depends upon various parameters such as their exposure conditions, oceanographic conditions, salinity, ballast water contamination, wind velocity and its direction. Structural health assessment of this marine structures are mainly corresponds to the corrosion of reinforcing steel embedded in the concrete. The present study is carried out to formulate the methodology for structural health analysis and monitoring of marine structures. The inspection reports and NDT test results helps to find the extent of spread of damages and level of deterioration of marine structures. Thus a protocol or handbook will give a clear information about particular type of distress and what should be the remedial measures for that distress. Thus, the most appropriate rehabilitation measures can be suggest.

Development of Scum Geometrical Monitoring Beneath Floating Covers Aided by UAV Photogrammetry

Floating covers are used on anaerobic lagoons at waste-water treatment plants for odour control and the harvesting of biogas. Scum is an unwanted by-product of the anaerobic digestion of raw sewage. This matter can form into a large mass of material, and when it floats to the surface and solidifies, it is called a scumberg to differentiate it from the scum which may still be in a semi-solid state. Given the continual inflow of raw sewage into the lagoon, the potential movement of the scum can deform the floating cover. One of the challenges pertaining to the structural health assessment of the floating cover hinges upon the difficulty in monitoring the development and geometrical profile of scum underneath the cover. The current measurement of scum requires the inspector to physically access the scum either from multiple discrete access ports within the floating cover or by using highly-skilled divers in the lagoon. In collaboration with Melbourne Water, a non-contact UAV-aided photogrammetry technique has been deployed to quantify the development of scum underneath the cover. It is shown that the digital elevation model obtained from photogrammetry correlates well with direct laser based measurements of elevation, and that cluster analysis can be used in conjunction with the digital elevation model to estimate the qualitative hardness level of the scum beneath the cover, thereby providing a viable alternative to time-consuming walk the cover type inspections. It is also shown that the total scum depth as predicted from the digital elevation model correlates well with the measurements taken through the access ports. This method could be a more effective alternative to current practice.