Optimal Placement of Precast Bridge Deck Slabs with Respect to Precast Girders using LiDAR

Abstract

-Many bridges have been constructed using precast components because they offer faster production, lower cost, and more efficient construction compared to conventional in-situ construction. For coupled behavior of bridges slabs and girders, shear pockets on the deck slabs and shear connectors on the girders need to be properly connected. However, precast girders can be easily deformed once they are placed on sites because of their heavy weights, time dependent effects of creep and shrinkage, pre or post tensioning, etc. Once the girders are deformed, shear pockets and shear connectors may no longer match properly. This study proposes a technique which can automatically identify mismatches between shear connectors and shear pockets using LiDAR and identify the optimal placement of precast deck slabs with respect to precast bridge connectors. First, precast bridge deck slabs and precast girders are scanned using a LiDAR. Then, unnecessary noise data are removed using a DBSCAN-based algorithm. Afterwards, the dimensional features such as locations and sizes of shear pockets and shear connectors are estimated from the point cloud data, respectively. Finally, the optimal placement of deck slabs is identified to minimize the mismatches between shear pockets and shear connectors using the Levenberg-Marquardt (LM) method. To validate the effectiveness of the proposed technique, an experiment was conducted on a real precast girder. The experimental results demonstrate that the proposed technique can effectively and efficiently estimate the optimal placement of deck slabs with respect to precast girders.