Curvature envelope area based rapid identification method of bridge distributional element stiffness using microwave interference radar

Abstract

The bearing capacity of a bridge mainly relies on its own stiffness, while, at present, it remains a challenge to identify the bridge stiffness rapidly. In this paper, a rapid and innovative identification method of bridge distributional element stiffness (BDES) is proposed based on microwave interference radar technology and curvature envelope area (CEA). The main contributions of the work are as follows: (1) Taking advantage of multi-point displacement synchronous measurement, the self-developed microwave inference radar makes possible the acquisition of rotation influence lines (RILs) through the measured multi-point displacement influence lines (DILs). (2) Based on the one-to-one accurate correspondence between CEA, moment envelope area (MEA) and stiffness (“point-to-point” matching), and using the essential relationships among CEA and rotation, the bridge stiffness can be derived by using the DILs and the MEA calculated from the calibrated moving load (“point-to-line” matching). (3) Due to the radar feature of synchronous observation over a large area and referring to the proposed stiffness identification method, the BDES of the monitored area can be further obtained (“line-to-surface” matching). The proposed bridge identification method was applied at a laboratory experiment to identify the BDES of a steel beam for both undamaged and damaged conditions, and the results support the feasibility of the proposed method in BDES identification.