Seismic Assesment of Simply Supported Vs Continuous Concrete Girder Bridges (Case Study of Selected Bridges)
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Date
2013-06
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Addis Ababa University
Abstract
Seismic evaluations of typical concrete girder bridges are conducted for two existing
simply supported bridges, which are common to the Ethiopian highway construction, and
for their counterpart continuous girder bridges. These evaluations are performed for an
approximate hazard level of 0.1g ground acceleration by performing linear modal
response spectrum analyses on three-dimensional analytical models. The results show
responses in the deck girder, reinforced concrete columns and bearings at the supports of
the girders. In general, the longitudinal loading of the continuous bridges results in larger
demands than the transverse loading. Consequently, the continuous nature of the deck
tends to transfer seismic demand to different structural components. Therefore, the
demands of piers for continuous girder bridges become larger. The simply supported
bridges sustain bearing deformations in the transverse direction which are of the same
value as the longitudinal response. These results suggest that both longitudinal and
transverse loading are significant and should be considered when performing seismic
assessment of these bridges. And also the modal response spectrum analysis result shows
that the contribution of higher modes in seismic response of the continuous bridges is
insignificant. Whereas it is noted that, the contributing higher modes should be considered
to obtain the seismic responses of simply supported girder bridges.
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Structural Engineering