4
J. Bujnak et al.
Fig. 1 Recommended permissible deflections
For greater speeds within the range 80 ≤ v ≤ 200 km/h as it can be seen in Fig. 1
from EN 1991-2 [2], the permissible deflections δ stat result from expression
d stat ≤ L/(15 v − 600)
(1)
The upper limit L/2400 for 200 km/h is the permissible deflection which has
taken during many years for designing bridges for high speed lines with satisfactory
results. For speed superior to 200 km/h, the dynamic study is obligatory. Determined
values should be minimally δ stat ≤ L/2400. Such limitations should guarantee that
the dynamic stresses due to actual trains at speeds smaller than or equal to 200 km/h
remain smaller than the stresses calculated with the LM 71 loading scheme, including
the dynamic factor. At the very high speeds in excess of 200 km/h, this check has to
be supplemented by dynamic calculations under actual traffic in order to cover any
resonance or excessive vibration of the girder.
The supplementary limitations on the displacement of deck ends beyond bearings
due to traction and braking are required for safety and comfort reasons of higher operational velocity, as indicated in Fig. 2. The relative longitudinal displacement δ 2 shall
not exceed 5 mm for continuous welded rails without rail expansion devices or with
a rail expansion device at one end of the deck and 30 mm for rail expansion devices
at both ends (Fig. 2a). For vertical traffic actions produced by non-classified model
LM 71, the longitudinal displacement δ 3 shall not exceed 8 mm when the combined
behaviour of structure and track is taken into account (Fig. 2b). The vertical displacement of the upper surface of a deck relative to the adjacent construction or another
deck abutment δ 4 due to variable actions shall not exceed 3 mm for a maximum line
speed at the site of up to 160 km/h and only 2 mm over this value (Fig. 2c). These
J. Bujnak et al.
Fig. 1 Recommended permissible deflections
For greater speeds within the range 80 ≤ v ≤ 200 km/h as it can be seen in Fig. 1
from EN 1991-2 [2], the permissible deflections δ stat result from expression
d stat ≤ L/(15 v − 600)
(1)
The upper limit L/2400 for 200 km/h is the permissible deflection which has
taken during many years for designing bridges for high speed lines with satisfactory
results. For speed superior to 200 km/h, the dynamic study is obligatory. Determined
values should be minimally δ stat ≤ L/2400. Such limitations should guarantee that
the dynamic stresses due to actual trains at speeds smaller than or equal to 200 km/h
remain smaller than the stresses calculated with the LM 71 loading scheme, including
the dynamic factor. At the very high speeds in excess of 200 km/h, this check has to
be supplemented by dynamic calculations under actual traffic in order to cover any
resonance or excessive vibration of the girder.
The supplementary limitations on the displacement of deck ends beyond bearings
due to traction and braking are required for safety and comfort reasons of higher operational velocity, as indicated in Fig. 2. The relative longitudinal displacement δ 2 shall
not exceed 5 mm for continuous welded rails without rail expansion devices or with
a rail expansion device at one end of the deck and 30 mm for rail expansion devices
at both ends (Fig. 2a). For vertical traffic actions produced by non-classified model
LM 71, the longitudinal displacement δ 3 shall not exceed 8 mm when the combined
behaviour of structure and track is taken into account (Fig. 2b). The vertical displacement of the upper surface of a deck relative to the adjacent construction or another
deck abutment δ 4 due to variable actions shall not exceed 3 mm for a maximum line
speed at the site of up to 160 km/h and only 2 mm over this value (Fig. 2c). These