Emergence of Semi-Integral Bridges

Abstract

At the 73rd TRB Annual Meeting in January 1994 the paper “Semi-Integral Bridges: Movements and Forces” was presented. It described the attributes, limitations, and peculiarities of a presumably new bridge concept developed by the Ohio Department of Transportation. That presentation elicited a comment from an attendee at the TRB meeting about recent research on a Washington State bridge, a bridge that was later found to be based on this same concept except that it predated Ohio’s earliest prototype by more than 10 years. This discovery of the Washington State experience provoked a state and province inquiry about semi-integral bridge construction, an inquiry that revealed the startling fact that fully 26 state transportation departments have constructed one or more of these structures; some departments have been constructing them for more than 20 years, and two departments have been constructing them for at least 40 years. Another surprising indication of semi-integral bridge experience was the discovery that the design of more than 80 percent of bridges built by two departments are based on the semi-integral concept. Because semi-integral bridges are deck-jointless bridges that can be designed to operate well within usual stress limits, because they are suitable for most moderate-bridge-length applications, because they can be designed to resist the destructive effects of rigid pavement growth and earthquakes, and because so many departments have achieved favorable performance with them, it appears that interest in semi-integral bridges will continue to increase, as will their numbers. However, since the stability of some semi-integral bridges depends to a great extent on composite backfill-structure interaction, future applications of this innovative bridge concept will depend to a great extent on the development of suitable soil-structure interaction research to provide the necessary experimental background to guide future designs.

Design and Performance of Jointless Bridges in Ontario: New Technical and Material Concepts

“…Other jurisdictions have similar limits on the basis of their experiences with the performance of these types of structures. Integral abutment bridges to lengths of 240 and 120 m and semi-integral bridges to lengths of 135 and 90 m, in concrete and steel, respectively, are reported to have been built (13,14). The limit of 150 m for Ontario is based on the province's success and experience with integral abutment bridges of this length.…”

Jointless Bridges and Bridge Deck Joints in Washington State

“…Pertinent bridge data and condition observations are included in the tables. Field inspections were conducted to Beginning in the mid-1960s, the Washington State Department of Transportation ( WSDOT) introduced the semi-integral bridge as a replacement for the integral bridge (1,2,3). WSDOT continues to use semi-integral bridges for short-to-medium span bridges to eliminate bridge deck joints and reduce costs associated with joint maintenance.…”

“…WSDOT continues to use semi-integral bridges for short-to-medium span bridges to eliminate bridge deck joints and reduce costs associated with joint maintenance. A secondary consideration is improved aesthetics by eliminating staining associated with leaking expansion joints at intermediate piers (3).…”

Experimental investigation of soil‐structure interaction for the transition slabs of integral bridges

“…It was in that context that the concept of integral bridges was introduced in the 1990s. Integral bridges are monolithic structures, built without expansion joints and often without mechanical bearings [1], [2], [3], [4]. This leads to a lower lifetime cost because the initial construction costs are lower and because there are no mechanical devices, which require periodic inspection, maintenance and, occasionally, replacement.…”

“…For longer bridges, a transition slab is used to accommodate the larger movements occurring at the bridge ends, avoiding the formation of transverse bumps and dips as well as cracking of the pavement. In these cases, bridge design guidelines typically limit the maximum length of integral bridges to 60-90 m [1], [2] or, more precisely, limit the maximum displacement at each bridge end [5], which is more appropriate, particularly in the case of existing bridges where long-term deformations have ceased to increase. For longer bridges, indeed for larger movements at the bridge ends, solutions with expansion joints are required.…”