# ISO 5049-1-1994

INTERNATIONAL STANDARD IS0 5049-I Second edition 1994-07-01 Mobile equipment for continuous handling of bulk materials - Part 1: Rules for the design of steel structures Appareils mobiles de manutention continue pour produits en vrac - Partie 1: R. - material loads; - incrustation; - normal digging and lateral resistances; - forces at the conveying elements for the ma- terial load; - permanent dynamic effects; - inclination of the machine; - loads on the gangways, stairs and platforms. The additional loads are loads that can occur intermittently during operation of the equipment or when the equipment is not working; these loads can either replace certain main loads or be added to the main loads. They include, among others: - wind load for machines in operation; - snow load; - temperature load; - abnormal digging and lateral resistance; - resistances due to friction and travel; - horizontal lateral forces during travelling; - non-permanent dynamic effects. The special loads comprise the loads which should not occur during and outside the operation of the equipment but the occurrence of which is not to be excluded. They include, among others: - blocking of chutes; - resting of the bucket wheel or the bucket lad- der on the ground or face; - blocking of travelling devices; - lateral collision of the bucket wheel with the slope; - wind load for machines not in operation; - buffer effects; - loads due to earthquakes. In addition, it may be necessary to take into ac- count the loads occurring on certain parts of the structure during assembly. 3.1 Main loads 3.1.1 Dead loads Dead loads are load forces of all fixed and movable construction parts, always present in operation, of mechanical and electrical plants as well as of the support structure. 3.1.2 Material loads The material load carried on conveyors and reclaimers is considered. 3.1.2.1 Material load carried on the conveyors These loads are determined from the design capacity (in cubic metres per hour). 3.1.2.1.1 Units with no built-in reclaiming device a) Where the belt load is limited by automatic de- vices, the load on the conveyor will be assumed to be that which results from the capacity thus limited. b) Where there is no capacity limiter, the design ca- pacity is that resulting from the maximum cross- sectional area of the conveyor multiplied by the conveying speed. Unless otherwise specified in the contract, the cross-sectional area shall be determined assuming a surcharge angle 6 = 20”. The maximum sections of materials conveyed are calculated in accordance with IS0 5048. c) Where the design capacity resulting from a) or b) on the upstream units is lower than that of the downstream units, the downstream units may be deemed to have the same capacity as the up- stream units. 3.1.2.1.2 Units fitted with a reclaiming device (bucket wheel or bucket chain) a) Where there is no capacity limiter, the design ca- pacity is 1,5 times the nominal filling capacity of 2 @a IS0 IS0 5049-1:1994(E) the buckets multiplied by the maximum number of discharges. In the case of bucket wheels, the factor 1,5, which takes into account the volumes which can be filled in addition to the buckets, can be replaced by taking into account the actual value of nominal and additional filling. b) Where there are automatic capacity limiters, the design capacity shall be the capacity thus limited. Where the unit is intended to convey materials of different densities (for example, coal and ore), safety devices shall be provided to ensure that the calculated load will not be exceeded with the heavier material. Dynamic load factor: In order to take into account the dynamic loads which could be applied to the conveyor during transport, the load shall be multiplied by a factor of 1,l. 3.1.2.2 Load in the reclaiming devices To take into account the weight of the material to be conveyed in the reclaiming devices, it is assumed that a) for bucket wheels - one-quarter of all available buckets are 100 % full; b) for bucket chains - - - one-third of all the buckets in contact with the face are one-third full; one-third of all the buckets in contact with the face are two-thirds full; all other buckets up to the sprocket are 100 % full. 3.1.2.3 Material in the hoppers The weight of the material in the hoppers is obtained by multiplying the bulk density of the material by the volume (filled to the brim). If ‘he weight of the material is limited by reliable dutomatic controls, deviation from the value given in 3.1.2.2 is permissible. X1.3 Incrustation The degree of incrustation (dirt accumulation) de- pends on the specific material and the operating con- ditions prevailing in each given case. The data which follow shall be taken as guidance. The actual values can deviate towards either higher or lower values. For storage yard appliances, the values are generally lower, while for other equipment (for example in mines) they shall be taken as minimum values. Loads due to dirt accumulation shall be taken into ac- count: a) on the conveying devices, 10 % of the material load calculated according to 3.1.2; b) for bucket wheels, the weight of a 5 cm thick layer of material on the centre of the bucket wheel, considered as a solid disc up to the cutting circle; c) for bucket chains, 10 % of the design material load calculated according to 3.1.2, uniformly dis- tributed over the total length of the ladder. 3.1.4 Normal digging and lateral resistances These forces shall be calculated as concentrated loads, i.e. on bucket wheels as acting at the most unfavourable point of the cutting circle, and on bucket chains as acting at a point one-third of the way along the part of the ladder in contact with the face. 3.1.4.1 Normal digging resistance The normal digging resistance acting tangentially to the wheel cutting circle or in the direction of the bucket chain (on digging units and, in general, on units for which the digging load is largely uncertain) is ob- tained from the rating of the drive motor, the effi- ciency of the transmission gear, the circumferential speed of the cutting edge and the power necessary to lift the material and (in the case of bucket chains) from the power necessary to move the bucket chain. To calculate the lifting power, the figures indicated in 3.1.2.2 may be used. For storage yard applications, the above method of calculation may be ignored if the digging resistance of the material is accurately known as a result of tests and if it is known for sure that this digging resistance will not be exceeded during normal operation. 3.1.4.2 Normal lateral resistance Unless otherwise specified, the normal lateral resist- ance can be assumed to be 0,3 times the value of the normal digging resistance. 3 IS0 5049-1:1994(E) Q IS0 3.1.5 Forces on the conveyor Belt tensions, chain tensions, etc. shall be taken into consideration for the calculation as far as they have an effect on the structures. 3.1.6 Permanent dynamic effects where fied because of local conditions. The aerodynamic pressure, q, in kilopascalsl), shall be calculated using the following generally applied formula: v2 q=m$ii 3.1.6.1 In general, the dynamic effect of the digging resistances, the falling masses at the transfer points, the rotating parts of machinery, the vibrating feeders, etc. need only be considered as acting locally. 3.1.6.2 The inertia forces due to acceleration and braking of moving structural parts shall be taken into account. These can be neglected for appliances working outdoors if the acceleration or deceleration is less than 0,2 m/s*. If possible, the drive motors and brakes shall be de- signed in such a way that the acceleration value of 0,2 m/s2 is not exceeded. If the number of load cycles caused by inertia forces due to acceleration and braking is lower than 2 x lo4 during the life-time of the machine, the effects shall be considered as additional loads (see also 3.2.7). 3.1.7 Loads due to inclination of the machine In the case of inclination of the working level, forces will be formed by breaking down the weight loads acting vertically and parallel to the plane of the work- ing level. The slope loads shall be based on the max- imum inclinations specified in the delivery contract and shall be increased by 20 % for the calculation. 3.1.8 Loads on the gangways, stairs and platforms Stairs, platforms and gangways shall be constructed to bear 3 kN of concentrated load under the worst conditions, and the railings and guards to stand 0,3 kN of horizontal load. When higher loads are to be supported temporarily by platforms, the latter shall be designed and sized accordingly. 3.2 Additional loads 3.2.1 Wind load for machines in operation During handling, a wind speed of V, = 20 m/s (72 km/h) shall be assumed, unless otherwise speci- VW is the wind speed in metres per second. The aerodynamic pressure during the handling oper- ation is then q = 0,25 kN/m* Calculating wind action: It shall be assumed that the wind can blow horizon- tally in all directions. The effect of wind action on a structural element is a resultant force, P, in kilonewtons, the component of which resolved along the direction of the wind is given by the equation P=Axqxc where A is the area, in square metres, presented to the wind by the structural element, i.e. the projected area of the structural element on a plane perpendicular to the direction of the wind; is the aerodynamic pressure, in kilo- newtons per square metre; is an aerodynamic coefficient taking into account the overpressures and underpres- sures on the various surfaces. It depends on the configuration of the structural el- ements; its values are given in table 1. When a girder or part of a girder is protected from the wind by another girder, the wind force on this girder is determined by applying a reducing coefficient v. It is assumed that the protected part of the second girder is determined by the projection of the contour of the first girder on the second in the direction of the wind. The wind force on the unprotected parts of the second girder is calculated without the coefficient r. 1) 1 kPa = 1 kN/m* 4 0 IS0 IS0 5049-1:1994(E) The value of this coefficient r] will depend on h and b (see figure 1 and table21 and on the ratio q+ e where A is the visible area (solid portion area); Ae is the enveloped area (solid portions + voids); h is the height of the girder; b is the distance between the surfaces fac- ing each other. When, for lattice girders, the ratio cp = A/A, is higher than 0,6, the reducing coefficient is the same as for a solid girder. Lattice of rolled sections Table 1 - Values of the aerodynamic coefficient, c Type of girder c Solid-web or box girders Members of circular section Tubular lattice (in metres) w -n q (in kilonewtons per square metre) d+ 1 0,7 NOTE - Certain values of c can be lowered if wind tunnel tests show that the values contained in the table are too high. Table 2 - Values of reducing coefficient q as a function of cp = A/A, and the ratio b/h q=+ or1 02 OR3 or4 or5 Or6 03 1 e b/h = 0,5 0,75 OS4 0,32 0,21 0,15 0,05 0,05 0,05 b/h = 1 0,92 0,75 0,59 0,43 0,25 O,l Otl 061 b/h = 2 0,95 03 0,63 0,5 0,33 02 02 02 b/h = 4 1 0,88 0,76 0,66 0,55 0,45 0.45 0,45 b/h = 5 1 0,95 0,88 0,8 l 0,75 0,68 0,68 0,68 NOTE - These values are also represented by the curves in figure 2. 5 IS0 5049-1:1994(E) 0 IS0 - * b c -c _ b )- II - Figure 1 - Height h and width b 0.8 U 0 02 0.4 0,6 0.8 1 Figure 2 - Curves giving values of q 3.2.5 Resistances due to friction and travel P=A Al? the bucket wheel or in the direction of the bucket chain is calculated from the starting torque of the drive motor or from the cut-off torque of the built-in safety coupling, taking into account the more un- favourable of the two cases listed below: a) if the wheel or chain is not loaded: in this case, account is not taken of the power necessary to lift the material to be transported, and the load due to the starting torque of the motor is considered as a digging load; b) if the wheel and chain are loaded according to 3.1.2.2: in this case, the digging power results from the starting torque of the motor, reduced by the lifting power. The abnormal lateral resistance is calculated as in 3.1.4.2, thereby considering a load of 0,3 times the abnormal digging resistance. If appropriate, this load can be calculated from the working torque of an existing cut-out device at least equal to 1,l times the sum of the torques due to the inclination of the machine (see 3.1.7) and to wind load for machines in operation (see 3.2.1). a) Frictional resistances need only be calculated as long as they influence the sizes. 3.2.2 Snow and ice load The loads due to snow and ice have been considered by the load case 3.1.3 (incrustation). If the customer does not prescribe load values due to particular cli- matic conditions, snow and ice need not be included. 3.2.3 Temperature Temperature effects need only be considered in spe- cial cases, for example when using materials with very different expansion coefficients within the same component. 3.2.4 Abnormal digging resistance and abnormal - on wheels of crawler-mounted machines: lateral resistance p =O,l The friction coefficients shall be calculated as fol- lows: - for pivots and ball bearings: p = 0,lO - for structural parts with sliding friction: p = 0,25 b) For calculating the resistances to travel, the fric- tion coefficients are as follows: - on wheels of rail-mounted machines: p = 0,03 The abnormal digging resistance acting tangentially to - between crawler and ground: p = 0,60 6 CJ IS0 IS0 5049-1:1994(E) -c HYl HY a Y ai1 3.2.7 Non-permanent dynamic effects The mass forces due to the acceleration and braking of moving structural parts occurring less than 2 x IO4 times during the lifetime of the appliance shall be checked as additional loads. They may be disregarded if their effect is less than that of the wind force during operation as per 3.2.1. If the mass forces are such that they have to be taken into account, the wind effect can be disregarded. 7 IS0 5049-1:1994(E) Q IS0 3.3 Special loads 3.3.1 Blockage of chutes The weight of material due to a blockage shall be calculated using a load which is equivalent to the ca- pacity of the chute in question, with due reference to the angle of repose. The material normally within the chute may be deducted. The actual bulk weight shall be taken for the calculation. 3.3.2 Resting of the bucket wheel or the bucket ladder on the face Where safety devices, for example slack rope safe- guard for rope suspensions or pressure switches for hydraulic hoists, are installed which prevent the full weight of the bucket wheel or the bucket ladder from coming to rest, the allowable resting force shall be calculated as a special load at I,1 times its value. Where such safety devices are not provided, the special load shall be calculated with the full resting weight. 3.3.3 Failure of safety devices as in 3.1.2.1 In the case of failure on the part of the aut