Monitoring of shear cracking in partially prestressed concrete beams by distributed optical fiber sensors

Abstract

In the present paper, a novel technique is used to monitor shear crack patterns in Partially Prestressed Concrete (PPC) beams. The proposed technique is based on experimental data obtained in two PPC beams tested in laboratory and instrumented by Distributed Optical Fiber Sensors (DOFS). In general, DOFS are using to monitoring axial or flexural structural behavior. This is the first time that a DOFS is used specifically, in shear structural laboratory tests. The DOFS conform optical fiber grids fixed in the surfaces of the beams. The DOFS used in this study provide continuous strain data with high spatial resolution and cracks can be characterized. The continuous (in space) monitoring of the strain along the optical fiber, including the crossing of a crack provides additional information without requiring prior knowledge of the cracked zone. Preliminary testing results of two beams are showed in this paper. This information is used to obtain crack initiation and location at different load levels recorded during the tests. In the future, based on this experi-mental data, a method to obtain average shear crack angles and crack width produced by shear forces will be proposed.