Toward improving the performance of highway bridge approach slabs.

PDFTech ReportCFIRE 03-10DTRT06-G-0020Highway bridgesBridge approachesBridge decksPrecast concrete pavementsRotationPerformance measurementBridge abutmentsDifferential settlementUnited StatesNational Center for Freight and Infrastructure Research and Education (U.S.)Oliva, Michael G.Rajek, GregoryUniversity of Wisconsin--MadisonUnited States. Dept. of Transportation. Research and Innovative Technology AdministrationNTL-HIGHWAY/ROAD TRANSPORTATION-Bridges and StructuresNTL-HIGHWAY/ROAD TRANSPORTATION-Construction and MaintenanceNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionThe objective of this study was to quantify the amount of rotation that could develop between an approach slab, after base settlement, and a bridge abutment. A better approach-bridge transition could then be developed by using a ductile concrete to directly connect the approach slab with a bridge deck and lessen or eliminate the annoying \ue2\u20ac\u153bump\ue2\u20ac? as well as maintenance problems associated with approach slab deterioration. In the future, acceleration bridge construction could then use high quality precast approach slabs directly connected to the bridge with a ductile concrete strip.To quantify the problems associated with approach slabs, particularly cracking and rotations, an extensive analytical study was conducted. Parameters included in the study were: approach slab length, slab material, subgrade soil type, abutment height, and possible settlement trenches that may develop under the slab near its support on the abutment.From the analyses it was concluded that end rotation of the approach slab near the abutment varied depending on geometry of the approach slab, trench and abutment as well as with the stiffness of the soil and concrete used in the analyses. A maximum rotation of 0.0045 radians was computed from the analyses in a situation with a loose soil and a 4 ksi concrete approach slab but 0.002 radians could be used for normal design