DEVELOPMENT OF CONCRETE LINK SLABS TO ELIMINATE BRIDGE EXPANSION JOINTS OVER PIERS

摘要

One of the primary factors affecting the durability of bridge structures is the use of expansion joints at bridge support locations. The inability of current joint systems to provide reliable and effective long-term leakproof performance generally leads to early leakage of chloridecontaminated water through those joints, thereby causing premature corrosion at girder ends and supporting substructures below. This problem is particularly evident in older-type multi-span bridges in which the girders are simply supported at the piers and are separated by expansion joints or paved-over joints. To address this problem, the Ministry of Transportation of Ontario has tried to eliminate the expansion joints during deck rehabilitation by using a number of approaches. This paper describes some of the systems that have been implemented in recent projects: (i) converting the simply-supported spans into a semi-continuous deck system by encasing the girder ends in a monolithic transverse concrete diaphragm, (ii) linking the simple spans by a thin concrete slab (flexible link slab) that spans between haunched beam sections on either side of link slab while keeping the girders discontinuous; and (iii) using a similar link slab concept except that the link slab is debonded from the girders for a longer length at each girder end. The paper discusses the relative merits of these systems from both technical and economic standpoints and provides examples of recent field applications of each system. The practical lessons that were learned and the field performance of each system to date are also presented.