Rehabilitation of reinforced concrete structures #3 Evaluation

 To the untrained eyes, an architectural drawing will look the same with the structural drawing. But there are huge differences between them. Do you know how to differentiate?

The next question when you suspect a deterioration of a reinforced concrete structures is how and what to evaluate? First, we must evaluate whether the damage is structural or superficial. The latter is not serious and a simple rectification can overcome the problem. It only affect the "cosmetic" of the structures. A crack on the wall may be due to the crack of the paint and does not affect the structural behaviour of the wall.

However, if the crack occur at the wall itself, then you might have a problem. But sometimes, it is quite hard for the untrained eyes to differentiate between the structural and superficial cracks. If you don't know what you are looking at, the cheapest way is to invite a friend (who is also a structural engineer) to you house for a lunch (or dinner) and ask for his opinions.

If you see something fishy with the crack, observe and record it behaviour such as the length, the direction it starts and propagates, the depth of the crack etc if you cannot find an engineer to do the inspection. This may help him to evaluate further.

Basically, there are three ways to evaluate the requirements for repairs. The first one,  is the visual inspections to see any abnormalities which then requires further evaluation and testing. The second is when a confirmed visual defects such as cracks, concrete spalling or exposed beam appearing; then a full investigation and evaluation are required. Finally a periodic testing which incorporates non-destructive testing (NDT) using specialised electronic instruments which is the safest way to check the strength of the structures.

Another important aspect of evaluation is to keep the records of construction particularly the structural drawing. It is a part of the construction documents that are typically filed before permits for construction are issued. This is important so that a thorough investigation can be performed properly. Some of these documents include:

• Design documents
• Structural drawings
• Site inspections records
• Laboratory test reports
• Maintenance reports

Next, schedule a site visit (with an engineer). Make sure you have the relevant documents ready. The engineer will visually inspect the damage. He will probably have a check list to record the inspection which includes cracks, discolouration or joint deterioration. A sketch may also be produced.

Dr. Ibrisam Akbar