Most cracks in concrete structures occur as a result of one or more of the following actions: settlement of plastic concrete, volumetric change, and direct and flexural stresses resulting from applied load or support reaction. Therefore reinforced concrete structures always suffer from cracks problem. Cracks reduced the stiffness of a structure. Physical and Chemical/Biological method could be used to detect deterioration location of the structures.
The aims of this research are to detect the deteriorations and to estimate a residual stiffness of a reinforced concrete bridge structures in damage environment. The research was conducted experimentally by measuring its vibration response subject to mechanical exciter as physical test and Nuclear Magnetic Resonance (NMR) as Chemical/Biological test. The responses from both testing were converted to get the mode curvature of the structure using numerical approach.
The results show that (a) extreme cracks location are on the 17 meters span, (b) The cracks located at 1.7 meters from the left end are predicted as a bounding crack, (c) maximum curvature of the structure is 4.5 x 10-4 on continuous support, (d) the residual stiffness of the structure decrease around 9%, (e) The strength decreasing of the concrete can estimated using NMR, (f) the damage structure classification proposed could be used to evaluated and indicate a reinforced concrete structure for strengthening.