## Combined footing

Design a combined footing supporting one exterior and one interior column. An exterior column, 600 mm x 450 mm, with service loads of 760 kN dead and 580 kN imposed and an interior column, 600 mm x 600 mm, with service loads of 1110 kN dead and 890 kN imposed are to be supported on a rectangular footing that cannot protrude beyond the outer face of the exterior column. The columns are spaced at 5.5 m centres and positioned as shown in Figure 7.2. The allowable bearing pressure is 175 kN m2, and...

## Pilecap design example using truss analogy

A four-pile group supports a 500 mm square column which carries a factored load of 2800 kN. The piles are 450 mm in diameter and spaced at 1350 mm centres. Assume a pilecap depth of 800 mm. Allow the pilecap to extend 150 mm beyond the edge of the piles, to give a base 2.1 m square as shown in Figure 7.7. Use 2.1 m x 2.1 m x 0.8 m deep pilecap For components in non-aggressive soil and or water, exposure class is 2 a . Minimum concrete strength grade is C30 37. For cement content and w c ratio...

## Twoway spanning solid slabs

EC2 1 permits the use of elastic analysis, with or without redistribution, or plastic analysis for ultimate limit state design. Elastic analyses are commonly employed for one-way spanning slabs and for two-way spanning slabs without adequate provision to resist torsion at the corners of the slab and prevent the corners from lifting. Plastic analyses are commonly used in other situations. Tabulated results for moments and shears from both types of analysis are widely available. Care is necessary...

## Concrete Nib Design

lt 0.0015 x 1000 x 81 122 mm2 Check minimum area of reinforcement for crack control 0.4 x 0.8 x 3.0 x 52.5 x 103 460 110 mm2 No further check for crack control Is necessary as h 105 lt 200 mm. Maximum bar spacing 3h 315 lt 500 mm The reinforcement details are shown in Figure 8.5. Figure 8.5 Nib reinforcement details Figure 8.5 Nib reinforcement details Check shear in nib, taking into account the proximity of the concentrated load 4.3.2.3 to the support. 0 2.5dlx 2 5 X 81 1.69 Eqn 4.17

## Concrete grades

EC2 1 uses the cylinder strength, fck, to define the concrete strength in design equations, although the cube strength may be used for control purposes. The grade designations specify both cylinder and cube strengths in the form C cylinder strength cube strength, for example C25 30. It may occasionally be necessary to use cube strengths which do not exactly correspond to one of the specified grades. In such instances a relationship is required between cylinder and cube strength in order to...

## Comparison with spaneffective depth ratio

The procedure for limiting deflections by use of span effective depth ratios is set out in EC2 Section 4.4.3. 100 4 100 x 2410 o _ UU 0.37 Therefore the concrete is lightly stressed, p lt 0.5 The NAD 1 introduces a category of nominally reinforced concrete corresponding to p 0.15 Basic span effective depth ratio for a simply supported beam, interpolating for p 0.37 For flanged beams where M gt w gt 3.0 the basic span effective depth ratio should be multiplied by a factor of 0.8 The span...

## References

Eurocode 2 Design of concrete structures. Part 1. General rules and rules for buildings together with United Kingdom National Application Document . DD ENV 1992-1-1 1992. London, BSI, 1992. 254 pp. 2. British standards institution. Structural use of concrete. Part 1 Code of practice for design and construction. Part 2 Code of practice for special circumstances. Part 3 Design charts for singly reinforced beams, doubly reinforced beams and rectangular columns. BS...