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ICS 93.040
ROMANIAN STANDARD
STAS 1545-89 Classification index G 61
Replacing: STAS 1545-80
Previous editions:
ROAD AND STEET BRIDGES; FOOTBRIDGES
Loads
Poduri pentru strzi i oosele - Aciuni
Ponts Routiers Passerelles - Actions Validation date:
1989-08-31
1 GENERAL
1 Scope 1.1.1 This standard refers to the determination of value
for loads that must be considered when designing road and street
bridges and footbridges, made of metal, concrete, reinforced
concrete, prestressed concrete, masonry or wood. 1.1.2 The
provisions of this standard are also valid for combined bridges, as
concerns the road part, when calculating only the influences of
road trains. For the railway part and whenever the influences of
railway trains come into calculation, the provisions of STAS
1489-78 are considered. 1.1.3 For important bridges, for bridges
that have an unusual building characteristic, as well as for
bridges with special destination (mobile bridges, removable bridges
etc.), specific norms or specifications can be elaborated, in the
meaning of this standard, which are applied under the agreement of
all stakeholders. 1.2 The technical weights of the materials of
which the construction elements are made comply with STAS
10101/1-87. 1.3 The classification and the groups of loads, as well
as their charging and grouping coefficients, are those of STAS
10101/OB-87.
2 PERMANENT LOADS 2.1 Way weight 2.1.1 The weight of the way
encompasses: the weight of the road system intrinsically, that of
the hydro-insulation coping, and that of the equalizing or slope
concrete, the weight of the boarding and that of the sidewalk
elements (in case they are not included in the strength structure),
the weight of the road guard elements, etc. The weight of the way
is determined based on the sizes adopted in the design of the
technical weights of the elements it is made of. 2.1.2 The weight
of the way is considered to be evenly distributed on the
longitudinal and transversal way of the bridge. When sizing the
sidewalk consoles, the weight of the road guard is considered to be
an evenly-distributed linear charge along the bridges and applied
towards the axis of the fixing strip. 2.2 Strength structure weight
2.2.1 The weight of the strength structure includes: weight of the
bridge covering and of its support elements, weight of the bearing
elements (cross-bars, main beams, etc.), as well as the weight of
the bracings.
ASOCIAIA DE STANDARDIZARE DIN ROMNIA (ASRO),
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ASRO Entire or partial multiplication or use of this standard in
any kind of publications and by any means (electronically,
mechanically, photocopy, micromedia etc.) is strictly forbidden
without a prior written consent of ASRO
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STAS 1545-89 - 2 - The weight of the strength structure is
determined based on the sizes adopted in the design and on the
technical weights of the elements it is made of. 2.2.2 The own
weight of the strength structure is considered for calculation
purposes as a charge distributed according to the real variation of
the sizes of the sections. It is admitted that the own weight of
the strength structure is considered as an evenly distributed
charge only in the following cases: - for metallic bridges of
constant height, with an opening smaller than 100 m; - for massive
bridges with an opening below 30 m, provided that the length of the
haunches is net over 1/10 of the opening; - for wooden bridges,
irrespective of the size of the openings and of the building
system. 2.3 Displacement of soil 2.3.1 Displacement of soil is
calculated taking into account the physical-mechanic
characteristics of the earth. These characteristics are established
through tests in geo-technical laboratories. The normative values
of the geo-technical characteristics represent average reference
values determined based on a number of tests corresponding to the
importance, construction type, and surface it occupies, as well as
on the homogeneity degree of the earth layer considered. The
calculation values of the geo-technical characteristics to be used
for ultimate limit states are determined by multiplying the
normative values in question by a safety coefficient for the
material K0, which takes into account the variability of the tests
results, determined according to STAS 3300/1-85. The limit states
for calculation are defined in STAS 10100/0-75, STAS 10111/2-87,
and STAS 3300/1-85. The establishment of normative and calculation
values of geo-technical characteristics is conducted according to
STAS 3300/1-85. 2.3.2 When geo-technical characteristics and K0
coefficient, determined as above, are missing, for backfills of any
height, composed of non-cohesive earths, or for backfills with
heights of at max. 4 m made of low cohesive earths (sandy clays,
sandy dusts, clay sands, etc.), the following normated values of
the characteristics needed for displacement of soil calculation are
admitted:
- interior friction angle = 33 - volumetric weight of regular
humidity earth = 18 kN/m3 - friction angle between earth and
masonry:
(1)
In calculations at ultimate limit states, the limit values of
the interior friction angle are established by allowing it to have
a maximal variation = 5, according to the most unfavorable case;
higher values are adopted for cohesive earths. The limit values for
volumetric weights of earth are established by multiplying the
normated values by the charge coefficients, according to STAS
10101/OB-87. 2.3.3 For geo-technical characteristics of natural
layer earths in the situation when there are not a sufficient
number of fields or laboratory determinations, based on the records
of carried out drillings, the calculation values for the interior
friction angle and cohesion of STAS 3300/1-85 can be informatively
adopted. 2.3.4 When calculating directly founded infrastructures,
with the foundation insertion depth of less than 5 m, the load of
the foundation earth passive displacement is taken into account. An
exception to this is the slide stability check of wings, bearing
walls and anchorage blocks, for which it is allowed to take into
consideration the passive displacement, provided that the movement
corresponding to the passive displacement does not have unfavorable
consequences on the building exploitation. The insertion depth is
considered starting from the lowest level of the river bottom
(after scouring). 2.3.5 For construction elements (abutments,
bearing walls, etc.) fitted with console drains, it is considered
that the displacement of soil acts in the separation plan between
earth and drain, on the console and drains height.
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STAS 1545-89 - 3 - If the drain is not propped against the
console, it can be considered that the displacement of soil acts in
the separation plan between land and drain, only if the drain has
the height of the element taking over the displacement, or if the
level of the elements foundation block is at least 1.00 m lower
than the drain level.
2.4 Prestress forces
The strains produced by prestress forces are determined
according to STAS 10111/2-87.
3 TEMPORARY LONG-TERM LOADS
3.1 Charges produced by the weight of objects or installations
mounted on the bridge
3.1.1 The charges produced by the weight of objects or fixed
installations which are mounted on the bridge (pipes, wires,
cables, as well as the weight of the devices bearing them) are
added to the calculation distinctly from the strength structure and
way weight and are determined based on the real sizes adopted in
the design and on the technical weights of the materials they are
made of.
3.1.2 When determining the loads given by pipes, the weight of
the fluids running through them is taken into account, as well as
by the loads occurring due to their exploitation technological
process, including the ones for testing purposes. *
3.2 Annual thermal variations
Annual thermal variation means the difference between the
construction completion temperature and the average summer
temperature, determined based on the isotherm of the month of July,
respectively, the average winter temperature, determined based on
the isotherm of the month of January.
The isotherms of July and January are established for the region
where the construction is situated, based on the climatologically
map. When accurate data is missing, the following average values of
isotherms can be admitted:
- July isotherm: + 15 C - January isotherm: - 5 C
The construction completion temperature is considered to be the
one shown clause 4.7.2.
For strain calculation, the values of the isotherms above are
considered to be the maximal temperatures of construction
materials.
3.3 Concrete deformations in time
3.3.1 The load of concrete deformations in time is taken into
account for calculating bridges statically undetermined, of plain
and reinforced concrete, when calculating metallic planks
cooperating with reinforced concrete bridge coverings, and when
calculating all prestressed concrete bridges.
3.3.2 The concrete deformations in time the load of which shall
be taken into account for calculation are slow flow and
contraction.
3.3.3 The value and the effects of the loads of concrete
deformation in time upon the strains in structures of reinforced
concrete, plain concrete, prestressed concrete, and upon metallic
ones cooperating with reinforced concrete covering, are determined
according to STAS 10111/2-87.
3.3.4 For constructions of concrete and reinforced concrete the
effect of contraction and of slow flow can be assimilated by a
simplified calculation, with a temperature decrease t considered to
be:
- t = 20 C, for plain concrete bolts or reinforced concrete
structures with an average reinforcement percentage of 0.5 %; - t =
15 C, for reinforced concrete bolts and arches with a minimum
reinforcement percentage stipulated in STAS 10111/2-87 and for
reinforced concrete structures with an average reinforcement
percentage of 1.5 %.
3.3.5 When special measures are taken for reducing the
contraction by consuming an important part of it, until
construction completion, the t value can be reduced by 5 to 10 C,
depending on the size of the time interval from concrete placing to
construction completion.
3.4 Foundation settling and movement
3.4.1 The sizes of foundation settlings and movements are
established according to STAS 3300/2-85, taking into account the
physical-mechanic characteristics of earths.
3.4.2 When determining strains caused by the settling and
movement of bridges made of concrete, reinforced concrete, and
prestressed concrete, it is recommended to take into account the
slow flow effect of concrete,
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STAS 1545-89 - 4 - 3.5 Average-level hydrostatic pressure and
underpressure 3.5.1 The average-level hydrostatic underpressure of
waters is taken into account for:
- calculating the slide and overturn stability of elements with
foundation depths of less than 5 m (depth at which the land
insertion of the element is not taken into account); - determining
the effective field pressures; - establishing the bearing capacity
of land (according to STAS 3300/1-85).
3.5.1.1 When calculating the stability and determining the
effective field pressures, it is considered that the hydrostatic
pressure acts by reducing the own weight of construction elements
and of volumetric weight of earth on their steps.
3.5.1.2 When establishing the bearing capacity of the land and
the conventional calculation pressures, the hydrostatic
underpressure acts by reducing the volumetric weight of the
earth.
The volumetric weight of the earth below water , taking into
account the hydrostatic underpressure, is determined by subtracting
10 kN/m3 of the volumetric weight of the saturated earth.
4 TEMPORARY SHORT-TERM LOADS 4.1 Train charges 4.1.1 Street and
road bridges are calculated according to STAS 3221-86 for charges
produced by motor trucks type trains of, special vehicles on wheels
or roller belts, and streetcars, according to the charge class of
the bridge. 4.1.2 In special cases, when calculating the bridges
located on routs for heavy and overweight machinery, or the bridges
located in industrial premises, other vehicle trains or
non-standard isolated vehicles are taken into account than those
stipulated in STAS 3221-86, provided they be pointed out by the
bridge administration authority and under the approval of entitled
authorities. 4.1.3 Establishing strains in the bridge structures is
carried out by using concentrated charges, charges distributed on
reduced surfaces given by trains stipulated in STAS 3221- 86,
evenly-distributed charges (equivalents) provided for in Annex A,
tables 5 to 10. 4.1.4 For combined bridges, road and railway, the
elements subjected only to the influence of road charges are
calculated according to the provisions of this standard, as well as
to those of STAS 3221-86, while the elements subjected only to the
influence of railway charges are calculated according to STAS
1489-78, and 3220-89. The elements subjected to both charge
categories are calculated for the simultaneous action of both
trains, as the strains produced by one of them are reduced by 25 %.
The 25 % reduction is applied to the train producing the lowest
strain. 4.1.5 The charges of motor truck trains, railway trains,
and of streetcars, are considered to be dynamically applied. The
charges of special vehicle trains, on wheels or roller belts, are
considered to be statically applied. In order to take into account
the dynamic load of charges transmitted by vehicle trains, they are
multiplied by a dynamic coefficient , the value of which is
established depending on the train type, on the static system
adopted, on the material the elements to be calculated are made of,
and on its calculation opening. 4.1.5.1 The dynamic coefficient by
which the charges transmitted by motor trucks are multiplied
4.1.5.1.1 For metallic superstructures and their isolated elements
(stingers, cross-bars, etc.), the dynamic coefficient is considered
depending on the conventional calculation opening L (defined in
clause 4.1.5.1.4.), as shown in table 1.
Table 1
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STAS 1545-89 - 5 -
4.1.5.1.2 For metallic infrastructures, the dynamic coefficient
is considered identically to that of the minimal adjacent
opening.
4.1.5.1.3 For superstructures of massive bridges, the dynamic
coefficient is considered depending on the construction system and
on the conventional calculation opening L, as of table 2.
Table 2
In case 5 < L < 45 m, respectively 20 < L < 70 m,
the value of the dynamic coefficient is determined by linear
interpolation between the limit values concerned, stipulated in
table 2. 4.1.5.1.4 In table 1 and 2, L represents the conventional
calculation opening of the element, defined as follows:
- for girder calculation, L is the distance between the axes of
the crossbars; - for crossbar calculation, L is the distance
between the axes of the main beams; - for the calculation of slabs
and plainly-propped beams, as well as that of frames, arches, and
one-opening vaults, L is the calculation opening respective; - for
the calculation of slabs, beams, frames, arches, and continuous
vaults, for the calculation of bending moments in field, L is the
calculation opening of the respective field, while for the
calculation of bending moments and of reactions on the bearings, L
is the arithmetic mean of the adjacent openings; - for the
calculation of beams with consoles and joints (Gerber), for console
beams, L is the distance between the bearings of those beams, while
for independent beams, L is the distance between the bearings
points on the consoles; - for the calculation of the console
elements, L is the length of the console except for crossbar
consoles, where is admitted equally to the dynamic coefficient of
the respective cross-bar; - for frame girder, all the elements of
the girder are calculated with the dynamic coefficient
corresponding to the beam system and opening, except for web
members, to which the dynamic coefficient of the respective
cross-bar is applied; - for structures made up of main beams,
stringers, and cross-bars, if the continuity and cooperation of all
elements is taken into account, the calculation of stringers and
cross-bars is conducted by admitting for them as well the dynamic
coefficient of main beams, for strains originating in cooperation;
- for the calculation of one-direction armored plates, L is the
calculation opening of the plate; for the calculation of
two-direction armored plates, L is the smallest opening; - for the
calculation of the elevations of infrastructures made up of frame
structures, the dynamic coefficient is considered the one
corresponding to the calculation of superstructure reactions.
4.1.5.1.5 For wooden bridges, irrespective of the calculation
opening of the elements, the dynamic coefficient is considered as
follows:
- for directly-loaded = 1.3; - for indirectly-loade- for
traverse and ma- for main beams bea- for resistance bridg- for the
remaining e
4.1.5.1.6 For the calculatioboxes, the dynamic coeffminimal
adjacent opening.
Bridge construction system
Slab-covered bridges, on beams or in frames Arch bridges
Vaulted bridges way elements
d way elements = 1.2; in beams directly bearing the resistance
bridge floor = 1.1; ring the bridge floor through traverse beams =
1.0; e floor of wooden bridges with asphalt flooring = 1.1; lements
of these bridges = 1.0.
n of bearing devices, hanging ties, joints, bearing boxes, and
pressure beneath the bearing icient is the same as that admitted
for calculating the heaved or suspended structure for
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STAS 1545-89 - 6 - 4.1.5.1.7 The dynamic load is not taken into
account in the following cases:
- for the calculation of sank culverts and massive bridges with
an earth filing on top of at least 0.50 m; - for the calculation of
piles and abutments made of masonry or concrete; - for the
calculation of foundation systems and effective field pressures; -
for the calculation of displacement of soil caused by charge of
vehicle trains.
4.1.5.2 The dynamic coefficient by which the charges transmitted
by railway trains are multiplied is considered according to STAS
1489-78. 4.1.5.3 The dynamic coefficient by which the charges
transmitted by streetcar trains are multiplied is the same as that
corresponding to the railway train circulated on welded
joint-tracks, as its value is established according to the
provisions of STAS 1489-78, depending on the circulation speed and
on the calculation opening of the element. 4.2 Centrifugal force
(for curved bridges) 4.2.1 For bridges located in curve with a
radius smaller or equal to 250 m, the load of the centrifugal force
exerted by motor vehicles and streetcars is taken into account. The
value of the centrifugal force produced by motor vehicles is
affected by the reduction coefficients stipulated in STAS 3221-86
point 2.2.9. depending on the number of arrays. For combined
bridges (road and railway), the size of the centrifugal force
transmitted by railway and road trains is cumulated, as the
dimension of the force transmitted by railway trains is determined
according to STAS 1489-78 provisions. The value of the centrifugal
force transmitted by streetcar trains is determined similarly to
that of the railway trains. Summing the effects of centrifugal
force on combined bridges is conducted according to STAS 3221-86
clause 2.5., observing the same provision as for vertical charges.
4.2.2 The value of the centrifugal force produced by the trains of
an array of motor vehicles is determined with the relation:
(kN) (2) 2= P
RC
127 where: the train circulation speed, in km/h, corresponding
to the geometrical characteristics of the curve where the bridge is
located; R the radius of the curve, in m; P the charge of the motor
vehicles train, in kN, multiplied by the dynamic coefficient. The
centrifugal force is considered applied at the height of the
conventional weight center of the vehicles heaving the horizontal
and perpendicular direction on the longitudinal axis of the bridge
(the way being oriented towards the exterior of the curve). 4.2.3
Special vehicles on wheels or roller belts are not considered as
transmitting centrifugal forces. 4.3 Charges produced by people
4.3.1 The bridge sidewalks outside localities are calculated for an
evenly distributed charge of 3000 N/m2 or for concentrated charges
of 1500 N set at 2.00 m intervals. 4.3.2 The charge of the bridges
with special vehicles on wheels or roller belts is not considered
simultaneously with the charge of sidewalks with people. 4.3.3
Footbridges and sidewalks of bridges within localities are
calculated for an evenly-distributed charge of 5000 N/m2
representing people agglomerations. 4.3.4 Bridges within localities
where people agglomerations can occur are checked for an
evenly-distributed exceptional charge of 5000 N/m2 covering the
carriageway and the sidewalks. 4.3.5 For charges produced by people
the dynamic effect is not applied. 4.3.6 Sidewalk sidebars and
consoles for bridges outside localities are calculated for a
horizontal displacement of 500 N/m applied at the upper level of
the current sidebar hand.
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STAS 1545-89 - 7 - The current sidebar hand is also checked at a
concentrated vertical charge of 800 N. 4.3.7 Sidewalk sidebars and
consoles of footbridges and bridges within localities are checked
for a horizontal displacement of 1500 N/m.
The current sidebar hand checked at a concentrated vertical
charge of 1200 N. 4.4 Inertia forces (for mobile bridges)
The inertia forces produced when mobile bridges move
horizontally or vertically or when they rotate are considered by
taking into account the mass of the elements which move or rotate
and the maximum linear or angular motion speed. 4.5 Displacement of
soil in type trains
The displacement of soil given by the calculation train is
determined by replacing the train by a layer of earth the thickness
of which is established according to the charge class of the
bridge, according to STAS 3221-86. 4.6 Vehicle braking 4.6.1 The
charge produced by the braking of vehicles is a force acting in the
plan of the way parallel to the longitudinal axis of the bridge.
4.6.2 The value of the braking force is established conventionally,
depending on the charged length L of the line of influence of the
reaction of the bearing considered as follows:
- for L 25 m: F = 0.3 P.B - for 25 < L 50 m: F = 0.6 P.B -
for L > 50 m: F = 0.9 P.B,
where: P the weight of the motor truck in the calculation train,
according to STAS 3221-86 B n/2 (approximated up to whole units),
where n is the maximum number of traffic lanes for the bridge. The
braking charge is not taken into account for special vehicles on
wheels or roller belts. 4.6.3 If streetcars also circulate on the
bridge, as well as for combined bridges (road and railway), the
braking force is established separately for the road part depending
on the respective number of traffic lanes, according to clauses
4.1.4 and 4.6.2 and for the railway or streetcar part according to
STAS 1489-78. 4.6.4 The braking force is calculated without dynamic
coefficient. 4.6.5 The braking force is considered to be
originating in all the arrays of vehicles running in the same
direction. 4.6.6 For the calculation of fixed metallic bearings and
the respective infrastructures, it is admitted that the charge
corresponding to a fixed hearing device is determined by extracting
of the whole braking force half of the charge produced by the
friction of the metallic mobile propping devices and dividing the
result to the total of the metallic fixed bearing devices.
Under no circumstances can, the horizontal charge thus
determined, corresponding to a metallic fixed bearing device, be
inferior to that which would result if all bearings were considered
fixed. 4.6.7 For the calculation of the metallic mobile bearings
and the respective infrastructures, it is considered that they take
over 50 % of the whole braking force when metallic mobile bearings
have sliding friction, and 25 % of the whole braking force, if the
metallic mobile bearings have rolling friction.
Under no circumstances can, the metallic mobile bearings
devices, take over from the friction more than the friction force
calculated according to clause 4.9.2. 4.6.8 The piles that the
metallic fixed and mobile bearing devices are set upon are
considered to be charged with the sum of the forces transmitted by
each bearing device, calculated according to the provisions of
clauses 4.6.6, and 4.6.7, but no more than it would result if all
bearing were fixed. 4.6.9 For the calculation of the abutment it is
allowed to neglect the braking force of vehicles set on the back
fills. 4.6.10 For the calculation of bridges with simple-beared
superstructures or continuous ones fitted with neoprene bearings,
the strains produced by braking infrastructures is determined by
considering the rigidity of the neoprene bearings and the rigidity
of the piles.
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STAS 1545-89 - 8 - 4.6.11 For the calculation of the
infrastructure of bridges with straight beams, the breaking force
is considered to be applied at half of the bearing device height.
For the calculation of frame bridges, the braking force is
considered applied along the axis of the ruler.
For the calculation of deck bridges with arches or vaults, the
braking force is considered applied along the axis of the
key-structure. 4.6.12 For the calculation of superstructure
elements transmitting the braking force to the fixed bearings, the
friction of the mobile bearings is not taken into account. 4.7
Daily thermal variations
4.7.1 Daily temperature variation means the difference between
the isotherm of July and the maximum summer temperature,
respectively the difference between the isotherm of January and the
minimum winter temperature. The differences between the maximum
summer temperature and the isotherm of July, respectively between
the minimum winter temperature and the isotherm of January, are
established for the region where the construction is located, based
on the climatological maps. When establishing the temperature
variations of the building material, the following features shall
be taken into account: the thermal inertia of that material, the
size of the construction element, and the size of the surfaces
exposed to the influence of air temperature. When certain
calculation data is missing, the following maximum and minimum
temperature values can be admitted:
- for metallic bridges: + 50 C and 30 C; - for massive bridges:
+ 25 C and 15 C.
When establishing the minimum and maximum values shown above,
the distinct thermal inertia of metal and of concrete or masonry
was considered. 4.7.2 If there are no other indications, it can be
admitted that the construction completion temperature is + 5 C to +
15 C, depending on the season and the region where the construction
is located. 4.7.3 It is allowed to neglect for calculation purposes
the load of the temperature variation for sank culverts of any
kind, with a covering layer of at least 1.00 m thick, as well as
for vaulted ones with an opening L 15 m and the
arrow 4.7.4 For bridges made of concrete, reinforced concrete
and prestressed concrete, the extreme temperatures mentioned in
clause 4.7.1 can be reduced by 5 C each if the minimum size d of
the section of the element calculated, including the possible
covering in earth or other insulating materials, is d 70 cm. If the
minimum size of the section of the calculated element is a 20 cm,
the stipulated values are admitted. For minimum sizes of the
section of the calculated element, comprehended between 20 cm and
70 cm, the reduction of the values of extreme temperatures is
determined through linear interpolation, between 0 (for 20 cm) and
5 (for 70 cm). For framed concrete elements, the minimum size is
considered equal to the sum of the wall thicknesses if the surface
of the section of the holes is 50 % bigger than surface of the area
delimited by exterior profile of the element. In the opposite case,
the section is considered filled, taking the minimum exterior size
as the minimum size. 4.7.5 For calculation the following linear
dilatation coefficients t can be adopted:
- for metallic bridges, t = 1.2 x 10-5; - for metallic bridges
cooperating with reinforced concrete planking and concrete bridges,
reinforced concrete and prestressed concrete t = 1.0 x 10-5; - for
natural rock masonry bridges t = 0.8 x 10-5;
4.8 Temperature difference between construction elements
For metallic bridges with metallic planking or cooperating with
reinforced concrete planking, short-term temperature differences of
15 C between various elements of the structure, are taken into
consideration. For bridges of reinforced or prestressed concrete,
such differences are limited to 5 C. The elements considered are
selected in such a manner as to achieve the most unfavorable strain
for the calculated element, provided that their different heating
is possible from the building point of view. No temperature
differences between construction elements are allowed in the
calculation of strains produced by the annual temperature
variation. The temperature difference between elements of the
construction is considered simultaneously with the daily thermal
variations.
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STAS 1545-89 - 9 - 4.9 Friction of mobile bearing devices 4.9.1
The friction-produced charge in metallic mobile bearing devices is
added into the calculation as a horizontal force parallel to the
longitudinal axis of the superstructure, the load line of which is
located at half of the bearing devices height.
4.9.2 The maximal value T of the friction force is determined
with the relation: T = f. N (3)
where: f friction coefficient, the value of which is established
depending on the type of bearing device, as follows: f = 0.2 for
bearings with sliding friction f = 0.03 for bearings with rolling
friction; N the reaction transmitted upon the respective bearing
device, the moment the friction force is produced. For mobile
bearing devices made up of other materials (neoprene etc.), the
friction forces are considered according to the specialized
technical regulations in force.
4.9.3 The friction force T is considered for the calculation of
bearing devices and their anchorages, for the calculation of
bearing boxes and for that of the infrastructure.
4.10 Wind pressure 4.10.1 The charge produced by wind pressure
transversal to the bridge is considered to be an evenly-distributed
force, applied on the whole surface or only on certain sectors,
depending on which is more unfavorable to the element in
question.
4.10.2 It is allowed to neglect the wind load on bridges with
openings inferior to 20 m and heights inferior to 10 m above ground
or low water level.
4.10.3 The wind pressure transversal to the bridge is considered
to be loading with the following intensities on exposed surfaces
(including the aerodynamic coefficient):
- in the case of a bridge charged with vehicles: 1500 N/m2; - in
the case of a bridge uncharged 2000 N/m2;
4.10.4 The calculation surface, for which the provisions of
point 4.10.3. are considered applied, is the following: - the total
lateral surface in the case of bridges with plain web beams, as
well as for infrastructures higher than the low water level by 10
m; - 0.4 A, for bridges with lattice beams and two main beams,
where A is the total surface determined by the beams exterior
profile; - 0.5 A, for bridges with lattice beams and three or more
main beams.
The lateral wind pressure on piles with a height above the low
water level of less than 10 m, or ground level, is neglected.
4.10.5 The train is considered to have a surface of 2.0 m high for
bridges, and 1.8 m high, for footbridges, measured from the way
level, and a length determined according to clause 4.10.1.
4.10.6 The wind pressure along the bridge is considered as
follows: - for lattice beams, 60 % of the transversal pressure; -
for the infrastructure, the same intensity as the transversal
pressure.
The longitudinal pressure of the wind is not considered
simultaneously with the transversal one. For plain web beams the
longitudinal pressure of the wind is not calculated on the
superstructure.
4.10.7 For combinated bridges with metallic structure, the
structure opposed to the wind is determined according to STAS
1489-78.
4.11 Water pressure and underpressure from average level to
maximum or minimum level 4.11.1 The influence of water
underpressure from average level to maximum or minimum level is
calculated according to clause 3.5. 4.11.2 The plus difference due
to underpressure to the maximum level, or the minus difference due
to underpressure up to the minimal level, are considered separately
from the average level hydrostatic underpressure, depending on
which is most unfavorable case for the calculated element. 4.11.3
For infrastructures or bearing walls located in waters with large
depths (storage storage basins, for instance) or for the
infrastructures of bridges carried out in sea areas, the water
hydrostatic load produced by waves is also considered.
-
STAS 1545-89 - 10 - 4.11.4 For bearing walls located on the
banks of rivers or lakes with large short-term variation of water
levels, the difference of water pressures in the front and in the
rear of the bearing wall shall also be taken into account. 4.12
Vehicle crashes into curves or safety sidebars 4.12.1 The load of
vehicle crashes is taken into account as a transversal horizontal
force, applied to the upper level of the border or to the
mid-height level of the safety sidebar.
4.12.2 The regulated value of the charge Iz, produced by the
crashing of motor vehicles into borders, is considered according to
provisions in subclauses 4.12.2.1. to 4.12.2.3.
4.12.2.1 In the case of motor vehicle trains: - for train A 30,
Iz = 4000 N/m; - for train A 13, Iz = 3000 N/m; - for train A 10,
Iz = 2000 N/m;
The charge Iz is considered evenly distributed on any length, in
the most unfavorable position.
4.12.2.2 In the case of special vehicles on wheels or roller
belts: - for V 80, Iz = 50000; - for S 60, Iz = 40000; - for S 40,
Iz = 30000;
The charge Iz is considered a concentrated force, applied in the
most unfavorable position.
4.12.2.3 The crashing forces mentioned in point 4.12.2. are not
increased by applying the dynamic coefficient, and the calculation
values are equal to the regulated ones.
The vehicle crashing against borders or safety sidebars is
included in fundamental exploitation group I for sidebar and
border. 4.13 Ice pressure 4.13.1 The ice pressure is only taken
into account when calculating the infrastructure of bridges over
the Danube or over storage storage basins. This load is considered
both transversally and longitudinally to the bridge.
4.13.2 The static load of continuous ice filed Qs depends on the
thickness and extent of the ice field, on the gradient of
temperature into its mass, and on the resistance of crystal ice
against crushing.
4.13.2.1 For a width of the ice field (D) below 50 m, measured
to the opposite shore, the value of the horizontal displacement Qs
can be calculated with the relation: (kN/m) (4) where: t0 initial
temperature, average for the ice thickness, in degrees, which can
be considered equal to 0.35 of the air temperature at that date;
the relation between the increase of the temperature of the ice
field in the time interval S, and the size of that interval in
hours. This increase of the ice filed temperature can be equal to
0.35 of the temperature increase in the same interval; h thickness
of the ice field. 4.13.2.2 In the case of an ice field width (D)
equal to or beyond 50 m, the value Qs calculated with the relation
(4) is multiplied by a coefficient a, as in table 3.
Table 3
D m
50...75 75...100 100...150 > 150
a 0.9 0.8 0.7 0.6
4.13.2.3 The interval S (hours) shall be large enough (4 to 6
hours) for the air heating registered to be able to get transmitted
to the whole ice mass and produce the corresponding thermal
dilatation.
4.13.2.4 The ice thickness, in meters, is considered equal to
0.8 of the largest thickness ever recorded in the storage storage
basin or in that section of the river flow.
-
STAS 1545-89 - 11 -
4.13.2.5 When needed records are missing, for a width (D) of the
ice field of 50 to 150 m and over 150 m, the values of the compact
ice layer displacement can be admitted, as in table 4.
Table 4
Thickness of ice field m:
0.5 0.7 1.00 1.20 1.50 Width D m Qs kN/m
50...150 over 150
70 70
150 100
250 150
350 200
550 250
4.13.2.6 The maximum thickness of the crystal ice layer on the
lower Danube is approximately 0.70 m. 4.13.2.7 Since 8/9 of the ice
thickness is found below water level, the displacements will be
considered at 0.4 h under water, a level which is established
within the allowed hydrological limits, in the most unfavorable
position. 4.13.2.8 The static load of the ice force-flow field,
gathered in front of the infrastructures The Ps component of the
ice-flow field acting horizontally, perpendicularly onto the bridge
infrastructure, is calculated with the formula: (5) where: is the
surface of the ice field; p1 is the friction force of the water
current to the interior surface of the ice-flow field; p2 is the
impulse force of the current on the exterior border of the ice-flow
field; p3 is the component of the own weight of the ice-flow, after
the current slope; p4 is the friction force pf the wind on ice-flow
surface; and are the angles between the normal on the bridge
infrastructure, and the direction of the current, of the wind. The
measures p1, p2, p3, p4 are considered equal to: p1 = 0.5 v2
p2 = 50 v2
p3 = 920 h.i. p4 = 0.002 w2 (6) where: v is the speed of the
current underneath the ice, equal to 0.8 % of the measured speed of
the free current, at the time of ice-flow accumulation (m/s).
For v 0.1 m/s, it is admitted that p1 = p2 = p3 = p4 = 0
w is the wind speed at an incidence angle 45 135 and a 1%
insurance (m/s); h is the thickness of the ice field defined as in
clause 4.13.2.4.; D is the average length of the ice field, along
the water flow (m/s); i is the water flow slope.
4.13.3 The dynamic displacement due to the construction being
hit by the isolated ice-free flow
The maximal displacement per width unit of the bridge
infrastructure is: (7) where: Rc is the compression strength of the
ice (without considering the local crushing), which is 450 kN/m2; h
is the thickness of the ice-flow; k2 is a coefficient that takes
into account the partial contact of ice with construction, equal to
0.6 for the initial stage, respectively 0.8 for the maximal
ice-flow level.
-
STAS 1545-89 - 12 - 4.13.4 The vertical load of vertical
elements pulling out The vertical load Fv, which is transmitted to
the isolate piles and to the groups of piles by the ice field, in
case the water level increases, is determined by the formula: (kN)
(8) where: h is the thickness of the ice field, in m; d is the
diameter of single piles or of groups of piles, in m. 4.13.4.1
Relation (8) is applicable in case there is a continuous ice field.
4.13.4.2 The column and the groups of piles around which the
continuous ice filed is produced for a radius of at least 20 h are
also considered isolate piles. 4.13.4.3 If the lighting between
piles is less than 1 m, the pulling out of load is calculated for
the entire group of piles. 4.13.5 The loads due to ice, determined
according to these provisions, are recommended to be stipulated and
checked by means of observations, in nature, extended to a period
of time as long as possible. 4.14 Snow charge Snow charge is
generally not taken into account for bridges. In special cases,
when there is a chance that snow charge happens at the same time as
train charge, as is the case of covered bridges, the provisions of
STAS 10101/21-78 are applied for determining the size of the
charge. 4.15 Charges that occur when installing superstructures
into consoles or other similar operations When establishing charges
that occur for the installation of superstructures into consoles or
other similar operations such as superstructure alterations or
strengthening works etc., the provisions of clause 4.16.1 and
4.16.2. shell be taken into account. 4.16 Charges originating in
element transportation, execution, and installation 4.16.1 The
charges that act upon the structure and each of its elements during
transportation, execution, and installation (own weight, scaffold
charge, equipments people etc.) are determined for each element and
specific execution stage, by taking into account the effective
respective situation and the provisions of this standard, as well
as of those of STAS 10101/1-78. 4.16.2 The own weight of elements
installed by crane or other hoisting machineries is multiplied by a
dynamic coefficient: = 1.2 for heavy elements G 200 kN = 1.1 for
heavy elements G > 200 kN. The own weight of hoisting
machineries used for installing the elements is multiplied by the
same dynamic coefficients.
5 EXCEPTIONAL LOADS
5.1 The crashing of ships and boats against the piles of bridges
over navigable water flows 5.1.1 For bridges over navigable water
flows or possible to become navigable, at the calculation of piles,
the load of ship and boat crashing is taken into account. 5.1.2 The
value of the forces transmitted by the crashing of ships and boats
is established based on special specifications.
-
STAS 1545-89 - 13 - When these are missing, the following
relations for determining the crashing force Q can be used:
- along the axis of the bridge: Q = 10 (Lv 20), kN (9) for ships
shorter than 150 m; Q = 10 (2 Lv 170), kN (10) for ships longer
than 150 m;
- transversally to the axis of the bridge: Q = 10 (2 Lv 40), kN
(11) for ships shorter than 150 m; Q = 10 (4 Lv 340), kN (12) for
ships longer than 150 m. where: Lv is the length of the ship or
boat. 5.2 Seismic charges Seismic charges for the calculation of
road bridges are established according to the seismic zonation STAS
11100/1-77 and to specific technical regulations in force. 5.3
Charges produced by the destruction of fixed installations The
charges produced by the destruction of fixed installations are
those which occur when pipes break and certain parts of the bridge
are flooded with the liquid leaking from the pipes, or due to the
breaking of wires of the electrical installations, or cables, etc.
The size of these charges is determined based on measurements or on
values communicated by the authority managing these
installations.
__________________
-
STAS 1545-89 - 14 -
ANNEX A
EQUIVALENTS FOR TYPE TRAINS A10, A13, A30, S40, S60, V80
A.1 The equivalents for trains of the types A 30 and V 80 are
shown in tables 5 and 6
Table 5 Translation NOTE all the values written wit a dot (e.g.:
72.0..; 88.0...)
Charge length
L m
Triangular influence lines with the vertex located on:
the middle of the opening the quarter of the opening the edge of
the opening
Train type:
Equivalents, kN/mh a coma (e.g.: 72,0 ...) in this table are to
be read with
-
STAS 1545-89 - 15 -
Table 6
NOTES
1 - The correction coefficients of the influence lines of the
moments of continuous beams with section constant to the openings
relation between the extreme and middle from 1:1 to 1:2 do not
exceed the limits specified in table 6 for the corresponding
sections. 2 The equivalents in table 6 are only used for
approximate calculations and drafts. Translation NOTE all the
values written with a coma (e.g.: 30,0 ...) in this table are to be
read with a dot (e.g.: 30.0...)
Charge length
L m
Shape of the influence limit for correction coefficient with
the
values:
Shape of the influence limit for correction coefficient with
the values:
Charge length
L, m
Equivalents for train type A30 kN/m
Equivalents for train type V 80 kN/m
-
STAS 1545-89 - 16 - A.2 The equivalents for train types A 13 and
S 60 are shown in tables 7 and 8
Table 7
Translation NOTE all the values written with a coma (e.g.: 61,8
...) in this table are to be read with a dot (e.g.: 61.8...)
Charge length
L m
Triangular influence lines with the vertex located at: middle
of
the opening quarter of
the opening edge of the
opening any point
Train type:
Equivalents, kN/m
-
STAS 1545-89 - 17 -
Table 8
NOTE The equivalents in table 8 are only used for approximate
calculations and drafts. Translation NOTE all the values written
with a coma (e.g.: 23,4 ...) in this table are to be read with a
dot (e.g.: 23.4...)
Charge length
L m
Shape of the influence line for correction coefficient with the
values:
Shape of the influence line for correction coefficient with
the
values:
Charge length
L m
Equivalents for train type A 13, kN/m
Equivalents for train type S 60, kN/m
-
STAS 1545-89 - 18 -
A.3 The equivalents for train types A 10 and S 40 are shown in
tables 9 and 10
Table 9
Table 10
NOTE The equivalents
Triangular influence lines with the vertex located at:
Charge length
L m
middle of the opening
quarter of the opening
edge of the opening
any point
Train type:
Equivalents, kN/m
Shape of the influence line for correction coefficient with the
values:
Equivalents for train type A10 kN/m
Charge length
L m
Transalation NOTE all the values in these tables written with a
coma in table 10 are only used for approximate calculations and
drafts.
(e.g.: 47,5; 0,75 ...) are to be read with a dot (e.g.: 47.5;
0.75...)
-
STAS 1545-89 - 19 - A.4 In tables 6, 8, and 10, the correction
coefficient v is determined with the relation:
where: is the surface of the influence line with curve-shaped
contour of length L; is half of the value of the product between
the length L of the influence line and the largest ordinate of the
influence line with curve-shaped profile. In tables 5 to 10 for the
values of the intermediate lengths of the influence lines, the
equivalent charges are determined by linear interpolation. In the
case of charge lengths of 10 m and longer, for the influence lines
with parabolic profile and of the same type as the curve-shaped
triangle stipulated in tables 6, 8, and 10, the equivalent charges
are admitted to be determined by the relations:
- for A 30 trains: k = k + (1 ) 1.7 - for A 13 trains: k = k +
(1 ) 1.115 - for A 10 trains: k = k + (1 ) 0.86.
where: is the correction coefficient k is the charge equivalent
for the triangular influence line with the vertex corresponding to
the longest ordinate of the curve-shapes influence line. The
strains produced by charges given by vehicles are determined by
multiplying the surfaces of the influence lines by the equivalent
charges. The charge of the influence lines is conducted according
to STAS 3221-86.
________________
Developed by : Ministry of Transports and Telecommunications
Institute for Highway, Naval and Air Transport Design Project
responsible: Eng. Cristea Ionescu Final version: Romanian Standards
Institute Eng. Magda Ionescu
Collaborators: - Ministry of Silviculture Economy and of the
Construction
Materials - General State Inspectorate for Investments in
Constructions - Central Institute for Research and Guiding in
Constructions - Committee for the Problems of City Councils -
Ministry of National Defence - Institute for Railway Design -
Institute for Technologic Research and Design in Transports -
Institute for Research and Design in Wood Industry - Research
Institute Timisoara IPROTIM -