Storage material densities
Standard concrete specification
The concrete shall be produced in accordance with BS8500 to meet an exposure condition of XD2 with an intended life of 50 years.
Design Scope / Philosophy
The reinforced concrete precast retaining wall unit has been designed in accordance with the latest set of Eurocodes.
The unit will be designed to be loaded from either side with the following conditions: retained material level with the top of the wall and with an applied surcharge of 10kN/m2 or a sloping backfill with a maximum angle of 35º without an imposed surcharge. The retained material will be assumed to be granular and drained with a specific maximum moist density of 18kN/m3. For more information on specific material densities see table 1.
All steel to be grade S275 UNO.
All Anchor Bolts to be min grade 4.6 UNO.
See detailed bolt calculations.
Holding Down Bolts
Threaded rod anchor bars in grade 4.6 are used to anchor the base of the retaining wall into the cast in-situ concrete base (by others). The length of the embedment will vary between units and loading, the minimum embedment depth into the in-situ base for the standard range is shown on pages 6 and 7. The rod is placed in the in-situ base through the preformed holes within.
Due to a nominal cover of 45mm (including Δc of 5mm) and the mix design used the standard range of retaining walls meet an exposure condition of XD2 with an intended working life of 50 years. Other exposure conditions can be designed for. Please contact Bison Precast for further details. The limiting crack width will be taken as 0.3mm.
Assumed to be uncracked, mass / reinforced concrete base of minimum strength 25N/mm2. This is to be designed by others to resist the overturning and sliding forces exerted by the retaining wall unit and to consider the allowable ground bearing pressure to the relevant site.
The primary job of the unit is to retain the material behind. To do this the stem and the base have been designed to withstand the applied forces. To resist overturning and sliding with a factor of safety of 2 for overturning and 1.5 for sliding respectively, the units require anchoring into a mass or reinforced insitu concrete base.
The grouted threaded rod will be post fixed into the suitable base below and secured with a washer plate on top of the unit to increase the bearing capacity onto the base slab and prevent punching shear of the bolt head through the unit. The resistance of the anchors into the base must be checked by others.
The overall ground bearing pressure must be checked by others and considered when designing the insitu support base.
All reinforcement to be high yield with a yield strength of 500N/mm2.
All reinforcement to be Type 2 deformed bars including any specified mesh.
Minimum lap length to be 40 x smallest lapped bar diameter.