This section outlines some typical deformations and stresses of bridge due to single load case. The goal is to give an understanding of the bridge's behaviour under loading. Further, the results from single load cases will explains a result from a load combination which often raise a question in verification for concrete and reinforcement. The single load cases are given in characteristic values.
Tandem (deformation)
As example of tandem point load the figure blow shown a tandem in centre span 2. The tandem
wheel is located 1m from the right edgebeam (Lane 1). It gives 9mm vertical deformation DZ at
the edgebeam outer points. The brake of this tandem gives 6mm deformation DX in longitudinal
direction.
On the annotation of the figures one can read the loadcase number, analysis number, value entity, component and the unit (m).
Click on the images below for enlarging in 3000 pixels.
Figure: Bridge vertical deformation DZ due to tandem (m).
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Figure: Cross section deformation from the figure above (m).
Figure: Bridge longitudinal deformation DX due to tandem brake (m).
Figures below show deformation and stress of bridge subjected for settlement 10mm at centre pier 3.
The stress values and contours are shown for the two
centre spans only. The highlighted black lines indicate
the edgebeams and the piers.
ICDAS automate the deck in square shell elements to ensure the node results can be easily selected in straightness.
It should be note that in detail analysis the colours range in the contour are not enough for the assessment. The user need to select the node results as symmetric as possible with regarding to the longitudinal and transverse direction.
The tension stress SX at bottom of deck is 800kPa at the centre pier (red), and the compressions are -492kPa at the two neighbour piers (blue)
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Figure: Vertical deformation of bridge due to 10mm settlement at centre pier (m).
Figure: Stress SX at bottom of the two centre span due to 10mm settlement at centre pier (kPa).
Load combination factors in SLS and ULS
Refer to the text book Concrete Bridge using LUSAS
Basis and Smart Combinations in LUSAS
Refer to the text book Concrete Bridge using LUSAS
Verifications
Refer to ICDAS Design Basis and the text book Concrete Bridge using LUSAS for verification of reinforcement and concrete in SLS and USL load combinations.
