Time-dependent behaviour of widened reinforced concrete under-bridge

Abstract

A B S T R A C T R I~ S U M I~The paper reports on data acquired during 700 days of monitoring a widened reinforced concrete underbridge. The deck was monitored before, during and after widening and both portions of the deck, existing and new, were instrumented. Concrete strains were monitored by means of embedment and surface Vibrating Wire strain Gauges (VWG).Predicted creep, shrinkage, thermal and settlement strains were evaluated by means of a finite element analysis. The creep and shrinkage factors used were those from the simplified form of the B3 model [1]. Good agreement between calculated and measured longterm strains was observed at almost all gauge positions.From the analysis carried out, it was found that the stresses from the time dependent phenomena of creep, shrinkage and temperature, combined with those from the settlement of abutments, were greater than the magnitude of stresses obtained from the design live load.

Literature Reviews and Summary of Concrete Bridge Seamless Broaden Technology

“…In fact, the joining problem between the existing and new bridge also appears in foreign countries in the highway expansion, especially in the development period of road network construction in the developed countries. But the environment protection was not valued at that time, besides, the economic of developed countries such as the United States of America is strong and land resource is rich, the seamless solution isn't usually considered, and thus just a few researches were conducted combined with specific engineering [4,5,8,9]. The main measures in that period are structural modification, and the researches are mainly about the strengthening technology for the seam.…”

“…However, the differences between the existing bridge and new bridge in the design, construction, service and maintenance, which are caused by different construction time, always lead to the strain discordant and stress defects in the seam. The defects will lead to apparent cracking destruction phenomenon after seamless broaden, the cause including different base settlement, concrete creep and shrinkage, temperature effect, prestressed effects, and different design rules or standards [4][5][6][7]. According to the general code for design of Highway Bridge and Culverts (JTG D60-2004), all the above factors belong to bridge permanent or variable actions.…”

Numerical Analysis on Transverse Splicing Structure for the Widening of a Long Multi-Span Highway Concrete Continuous Box Girder Bridge

“…Currently, integral widening, in which the new section of the structure is made continuous with the existing one, is attractive because it avoids the complication of a movement joint that would often be below a running carriageway [ 1 ]. Under this scheme, the substructures of new and existing bridges are separated from each other, while their superstructures are transversely spliced together through structural connections and collectively subjected to overall stress, as shown in Figure 1 .…”

“…The interactions between the new and existing bridges are incurred by their different completion times, producing restraint stresses in the new and existing structures. For instance, the significant differences in their different completion times between the new and existing bridges would result in a series of deformation differences between them, including the longitudinal shrinkage and creep deformation of concrete, vertical foundation settlement, and so forth [ 1 ]. To be specific, the longitudinal concrete shrinkage and creep deformation of the new bridge are restrained by the existing bridge, which not only produces secondary structural internal forces but also causes overall transverse bending deformation in the widened bridge [ 2 , 3 , 4 , 5 , 6 ], as shown in Figure 2 .…”

Parsing on the Processing Methods of Seamline for Concrete Bridgewith Seamless Broaden Technology

“…In view of the design, construction, usage, maintenance between the old and new bridge, which is caused by different construction time, all lead to strain discordant and stress defects in the seamline. Besides the difference lead to apparent cracking destruction phenomenon after seamless broaden, the cause including different base settlement, concrete creep and shrinkage, temperature effect, prestressed effects, and different design rules or standards [1][2][3]. According to the general rules of the highway and bridge design, all the above factors belong to bridge permanent or variable function category.…”