Click here to load reader

View

111Download

40

Embed Size (px)

DESCRIPTION

STAS 1545-89-ENG

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),

Adresa potal: str. Mendeleev 21-25, 70168, Bucureti 1, Direcia General: Tel.: +40 1 211.32.96; Fax: +40 1 210.08.33, Direcia Standardizare: Tel. : +40 1 310.43.08; +40 1 310.43.09, Fax: +40 1 315.58.70,

Direcia Publicaii: Serv. Vnzri/Abonamente: Tel: +40 1 212.77.25, +40 1 212.79.20, +40 1 212.77.23, +40 1 312.94.88 ; Fax : +40 1 210.25.14, +40 1 212.76.20

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

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.

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,

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

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

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.

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.

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.

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 -