Analysis of Displacement Influence Line Characteristics of Simply Supported Beam with Local Damage

According to energy principle, the influence line equation for displacement at any point of simply supported beam with local damage was derived. Based on the load symmetry positions' difference of influence line for displacement at mid-span point, a index that detects the local damage of simply supported beam without initial data was proposed. The influence line characteristics of simply supported beam with local damage were theoretically analysed. Through further numerical experiments, the sensibility of the influence line for displacement at mid-span point was analysed when a local damage is in different location of the beam respectively. The equations and numerical experiments show that the index peak appears in the damaged area and the additivity of multi-damage index is proved. Using the facile and accurate displacement information in engineering, this algorithm provides some reasonable suggestions for the damage detection and analysis of this kind of structure.