Detail design includes but not limited to beams, columns, slabs, walls, beam column. They are a blend of the gravity wall and the cantilever wall designs. We wanted a neon sign of our names but are looking for a cheaper option so are thinking we could project an image instead. A contractor is to construct a reinforced concrete retaining wall 3.
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The fundamental requirement is that the wall is capable of holding the retained material in place without undue movement arising from deflection, overturning or sliding. Within these groups many common variations exist, for example cantilever walls may have additional supporting ties into the retained material.
The structural action of each type is fundamentally different, but the techniques used in analysis, design and detailing are those normally used for concrete structures.
As illustrated in figure It is generally taken as a requirement that under working conditions the resultant of the self-weight and overturning forces must lie within the middle third at the interface of the base and soil. This ensures that uplift is avoided at this interface, as described in section Friction effects which resist sliding are thus maintained across the entire base. Figure Friction force Self-weight Bending, shear, and deflections of such walls are usually insignificant in view of the large effective depth of the section.
Distribution steel to control thermal cracking is necessary, however, and great care must be taken to reduce hydration temperatures by mix design, construction procedures and curing techniques. The basis of design of counterfort walls is that the earth pressures act on a thin wall which spans horizontally between the massive counterforts figure These must be sufficiently large to provide the necessary permanent load for stability requirements, possibly with the aid of the weight of backfill on an enlarged base.
The counterforts must be designed with reinforcement to act as cantilevers to resist the considerable bending moments thai are concentrated at these points. The advantage of this form of construction is that the volume of concrete involved is considerably reduced, thereby removing many of the problems of large pours, and reducing the quantities of excavation. Balanced against this must be considered the generally increased shuttering complication and the probable need for increased reinforcement.
Hi Cantilever walls These are designed as vertical cantilevers spanning from a large rigid base which often relies on the weight of backfill on the base to provide stability.
Two forms of this Figure In both cases, stability calculations follow similar procedures to those for gravity walls to ensure that the resultant force lies within the middle third of the base and that overturning and sliding requirements are met.
This is demonstrated by the simple case of a gravity wall as shown in figure The critical conditions for overturning are when a maximum horizontal force acts with a minimum vertical load.
To guard against failure by overturning, it is usual to apply conservative factors of safety to the forces and loads. Tabic For resistance to overturning, moments would normally be taken about the toe of the base, point A on figure Thus the requirement is that Resistance lo.
Resistance provided by the passive earth pressure on the front face of the base may make some contribution, but since this material is often backfilled against the face, this resistance cannot be guaranteed and is usually ignored. Failure by sliding is considered under the action of the loads corresponding to the ultimate limit state of GEO. Table
DESIGN OF COUNTERFORT RETAINING WALL EXAMPLE FILETYPE PDF