BS6779-2-1991公路上车辆放置设备用护栏.第2部分放置设备用混凝土结构护栏规范

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发布时间：2022-06-25

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OIntroduction
1 Scope
0.1 This Part of BS 6779 specifies requirements for
This Part of BS 6779 specifies requirements for the
the design and construction of concrete parapets,
design and construction of in situ and precast
intended to provide specific levels of vehicle
concrete parapets which are designed to provide
containment on highways. These parapets are
specified levels of cont ainment for vehicles on
installed on bridges, retaining walls or other
highways. The requirements for minimum panel
structures.
length and for the prevention of composite action
Parapetsofmetal or of combined concrete and metal
with the main structure limit the direct application
are not covered in this Part of BS 6779.
in the case of bridge decks to those of 7.5 m and
0.2 The specification requirements are based upon
greater span. As they are of solid construction they
the results of tests on panels of 2.1 m and 3.0 m
also provide effective pedestrian protection without
lengths and it is considered reasonable to
modification.Parapets are to be prevented from
extrapolate to include panel lengths from 1.5 m
acting oompositely with the main structure by
to 3.5 m. Designers wishing to use panel lengths
dividing them into panels. Parapets designed to act
outside these limits will have to form their own
compositely as part of the main structure are
judgement as to making further extrapolation in the
outside the scope of this Part of BS 6779 as are
prestressed concrete parapets, parapets of metal
light of the individual circumstances.
construction and parapets of combined concrete and
0.3 The design of free standing panels and of panels
metal design.
having adequate shear transfer arrangements are
NOTE The titles of the publications referred to in this standard
covered.
are hsted on the inside back cover.
0.4 Containment levels are related to defined
vehicle impacts and normal and high levels of
2 Definitions
containment are specified. A low level of
For the purposes of this Part of BS 6779 the
containment, used in Part 1 of this series for the
following definitions apply.
design ofmetal parapets in certaincireumstances, is
not considered appropriate toconcrete construction.
2.1
Appendix A to Part 1 of this series outlines the
vehicle restraint system
derivation of design forces in relation to
an installation to provide a level of containment for
containment levels. The normal level of
errant vehicles to limit da mage or injury to users of
containment specified in BS 6779 is considered to
the highway
offer a reasonable level of protection under all but
2.2
the most exceptional cases.
highway parapet
0.5 The main objectives of the forms of parapet
a barrier at the edge of a bridge, or on top of a
defined in this Part of BS 6779 are:
retaining wall or similar structure,associated with
a) to provide specified levels of containment to
a highway
limit penetration by errant vehicles;
2.3
b) to protect highway users and others in the
safety fence
vicinity by redirecting errant vehicles with
minimum deceleration forces on to a path as close
an installation,provided for the protection of users
as possible to the line ofthe parapet and to reduce
of the highway, consisting of horizontal beams
the risk to the vehicle of overtopping the parapet
mounted on posts
and of overturning.
2.4
0.6 It is possible in the case of concrete parapets to
safety barrier
give theoretical design criteria to produce
an installation,provided for the protection of users
satisfactory designs. This is because the dynamic
of the highway, that is continuously in contact with
response of such rigid structures is relatively
its supporting foundation
predict able. In consequence full scale acceptanoe
2.5
testing, as required for metal parapets in
transition system
Part 1 of BS 6779; is not necessary.
an arrangement for connecting dissimilar and/or
different capacity protective systems
2.6
front face of a parapet
the face nearest to the traffic