Corrosion and service life
To ensure a long service life MultiPlate steel structures are provided with a
corrosion protection of high quality, the Duplex system consisting of hot-dip galvanizing
and epoxy coating. By additionally applying the epoxy coating on the zinc coated steel the
protection period is considerable increased. A synergistic effect is the result, i.e. the
zinc protects the coating from infiltration and the coating the zinc from corrosion
attacks.
Sufficient evidence of satisfactory long-term performance is now available with many years
of experience in Germany and even more in USA and Canada.The service life of MultiPlate
structures with a corrosion protection of the type Duplex system can be compared to the
service life of massive structures.
Hamco's own investigations on 30-40-year-old structures measuring the coating thickness(
here: galvanized structures only) showed no objections to the corrosion protection.
In the first 20 to 30 years no maintenance is required.End finish
Corrugated steel pipes are engineering structures, which itself do not fulfil any
high-standard design characteristics. The architectural integration in local landscape is
mainly determined by the design of the structure ends.
Dominating in slope design are bevel ends with collars of regular and irregular rocks or
paving. Facing of the bevelled ends can be an effective design detail.
Bevelled cut ends or vertical cut ends, in general are designed parallel to the centre
line of the road not considering the skew-no.. Considerable deviation of more than 90°
require a statical computation.
Cut end sheeting on an underpass profile
Cut end sheeting on an underpass profile |
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Statical
principle
The flexible embedded, corrugated steel pipe is a statical compound system consisting of
the flexible acting steel pipe and the supporting surrounding soil body (bedding body),
i.e. as a structural component the required soil construction shares in the carrying
capacity.
The stiffness of the pipe wall is restricted to allow the embedded pipe to deform
elastically and plastically under loading until a thrust line load is reached and soil
reaction pressures are formed.
In simple words, the size of the passive earth pressure is utilized, which resists the
deformation of the pipe. The flexible pipe is able to develop earth reaction pressures and
carry the load by means of normal forces without much requiring the bending resistance of
the pipe wall. The loads are mainly carried off in circumferential direction of the pipe
wall and may be neglected in longitudinal direction of the pipe wall. The small stiffness
of the pipe wall in this direction allows the pipe wall to accept large differential
settlements without influencing the carrying capacity. The transfer of normal forces of
the pipe wall is made with a shear joint, the ultimate strength of which was ascertained
in tests carried out by a recognized institute.
To ensure the described carrying behaviour the installation instructions specify the
statically required soil material characteristics of the surrounding bedding area.
Pipe size, pipe shape, corrugation, plate thickness and soil characteristics define the
carrying capacity of the corrugated steel pipe.
The static calculation with proof of permanent traffic loads and/or bridge classes are
made in accordance with the method Klöppel/Glock.
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Head wall for discharge
pipes for gravel |
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Horizontal bends in a
Multiplate structure |
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Assembly of discharge
pipe for gravel |
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more |
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