EVALUATION OF COMPRESSIVE STRENGTH DEGRADATION OF CONCRETE USING A MODEL BASED ON SURVEY DATA

The studies of the reduction in compressive strength of concrete structures built before 1975 through survey data at the construction site. The survey results were conducted on structures (columns, beams, floors) at different floors, and the specimens were tested to determine compressive strength (Ri, Rhttb, Rmin) according to the TCXDVN 239:2006 standard. Using the parabolic model to evaluate the influence of concrete strength at the floor positions, the results showed that the model was consistent with the data (R² = 1). On the other hand, the survey data also showed that the concrete strength of the columns was lower than that of the beams and floors and tended to increase with the height of the floors. This study clarified that the compressive strength of concrete in construction tends to decrease between floors, columns, beams, and floors, thereby providing appropriate solutions to upgrade the construction to ensure the structural safety of the construction when in use.