Civil Engineering Reference
In-Depth Information
Lawver et al. (2000) investigated a 66 m three-span integral bridge. The bridge
was monitored during construction, and for several seasons. The bridge components
were found to have performed within design limits. The bridge abutments were
found translating laterally as a reaction to expansion and contraction of the deck.
The effect of temperature changes on the bridge was determined to be as large as
the live-load effects.
Barker and Carder (2001) evaluated the behavior of a 50 m integral bridge dur-
ing construction and subsequently over the period of three years in service. The
abutment movement and corresponding earth pressure, as well as the strains and
temperature of the deck were recorded. The observation indicated that the earth
pressure behind the abutment at the backfill stage was comparable to the earth-
pressure at rest. This pressure increased slightly above the at-rest value during the
expansion cycles, with relatively higher pressures recoded towards the top of the
abutment.
Xu et al. (2003) performed a numerical analysis of an embedded 12 m high in-
tegral bridge abutment to investigate the distribution and magnitude of lateral
earth pressure developed during thermal cycles. A ±10 mm cyclical horizontal
movement of the top of the abutment was simulated for several cycles. This analy-
sis indicated that the bending moments increased with the increase in the number
of cycles, but said increase became negligible after 20 cycles. The lateral earth
pressure behind the abutment increased approximately 20% during the same
cycles.
2.4 The Case of Rigidly Framed Earth Retaining Structures
The authors could not find any studies on the case of rigidly framed earth retain-
ing structures (RFERS) such as those presented in Chapter 1. This class of struc-
tures resembles that of the integral bridge abutment since it can also be subject to
cyclical thermal loading, however, three fundamental differences exist between
RFERS and integral bridges. First, RFERS generally retain soil on one side and
are free to move on the other, unlike integral bridges, which are braced by soil at
both ends. Second, while integral bridge abutments are generally analogous to
single story frames, RFERS are typically multistory structures. Finally, depending
on the aspect ratio of the RFERS, and given that soil is present on one end only,
the stiffness of RFERS can vary greatly.
