A DENSITY APPROACH FOR DAMAGE IDENTIFICATION ON REINFORCED CONCRETE BRIDGE DECKS.

Abstract

This study presents structural damage identification using power spectral density (PSD) approach for reinforced concrete bridge decks at varied deck thicknesses. The effect of vibrations due to the applied load on the bridge decks were examined using finite element analysis (FEA) as coded in ABAQUS CAE software. AASHTO LRFD design equations were used to evaluate the loadings responsible for the intrinsic stresses generated in the bridge decks during their design period. An increasing decline in the internally resistive stresses was observed as the deck thickness was increased, which is consistent with experimental data. It was observed that the deck thickness has a great effect on the response to vibrations due to the applied loads. The 200mm deck thickness had more response to the effect of the applied load and vibration than the 225mm and 250mm deck thicknesses respectively. This is simply because the increase in thickness of the deck serves as a damper, hence reduces the frequency of excitation in the deck. Most bridge decks in reinforced concrete are generally of 200mm thick, hence, the cracking and frequency of maintenance. Thus, it is economically justifiable to justify increase in deck thickness to at least 225mm or 250mm in order to improve on durability, reduce deck cracks, maintainability, durability, and justify investment of funds. This will also reduce the effect of spalling of concrete and improve bond strength between concrete and the reinforcements.