243 FALSEWORK - TECHNICAL INFORMATION - 2023 FALSEWORK Absolutely prevent bearing on ground with unknown bearing capacity. In these particular cases, change the location of the falsework or increase the load spreading. Bearing on concrete slab In general, a tower does not require any particular preparation when it bears on a concrete slab. If the surface is uneven, wooden planks should be used between the base and the concrete. It may be necessary to provide falsework under the lower levels if they are unable to take the vertical loads. Differential subsidence The four feet of the tower must bear on the same type of surface so that the subsidence under each foot is identical. If this is not possible, for example, if two legs bear on a concrete slab and two bear on natural ground, the load on the legs on the natural ground must be spread to minimise subsidence. Bearing on natural ground On natural ground, the load must be distributed appropriately, depending on the nature of the ground and the load. Verification It is important to check that F < p x S F: downward force on standard; p: ground bearing capacity and S: bearing surface area on the ground. If this is not case, the bearing area should be increased by using an additional support. In practice, wooden planks, wood beams or solid timber are often used for load spreading. The calculations should assume that the load is spread in a cone with an aperture angle of 90°. When a = plate width = 15 cm A = 2 H + a The wedge is frequently larger than the load spreading cone. If the wedge is larger than “A” in any direction, the dimension can still be used for calculating the bearing area provided that the dimension is less than or equal to L max where: Max. L ≤ A + 3 H INFORMATION
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