## Eccentricity Of Prestressing

In the design of a reinforced concrete beam subjected to bending it is accepted that the concrete in the tensile zone is cracked, and that all the tensile resistance is provided by the reinforcement. The stress that may be permitted in the reinforcement is limited by the need to keep the cracks in the concrete to acceptable widths under working conditions, thus there is no advantage to be gained from the use of the very high strength steels which are available. The design is therefore...

## Magnel Diagram Equations

4.08 x 10fi x 24 - 59.4 x ' 0.8 4.08 x 106 70000 - 75 and allowing for the division by the negative denominator P gt -2881 kN Similarly from equations 11.18 lo 11.20 Pn lt 1555 kN P0 gt 557 kN P lt 654 kN The minimum value of preslress force is therefore 557 kN with an upper limit of 654 kN. b Check the upper economic limit to preslress force From equation 11.23 lt 12 x 350 x 200 x 10' 3 0.8 Since this is greater than the upper limit already established from equation 11.20 a design with an...

## Yield line and strip methods

For cases which are more complex as a result of shape, support conditions, the presence i openings, or loading conditions it may be worthwhile adopting an ultimate analysis ethod. The two principal approaches are the yield line method, which is particularly litable for slabs with a complex shape or concentrated loading, and the strip method hich is valuable where the slab contains openings. These methods have been the subject of research, and are well documented although hey are of a relatively...

## Ribbed and hollow block floors

Cross-sections through a ribbed and hollow block floor slab are shown in ligure 8.15. The ribbed floor is formed using temporary or permanent shuttering while the hollow block floor is generally constructed with blocks made of clay tile or with concrete containing a lightweight aggregate. If the blocks are suitably manufactured and have adequate strength they can be considered to contribute to the strength of the slab in the design calculations, but in many designs no such allowance is made....

## Bent Up Bars In Beams

Total ultimate load on beam 200 x 8.0 1600kN Support reaction 1600 2 800 kN Shear, Vtl at face of support 800 - 200 x 0.3 2 770 kN Shear. Vu distance ct from face of support 770 200 x 0.65 640 kN 1. Check the crushing strength VRd maxof the concrete diagonal strut at the face of the beams support. 0.124 x 350 x 650 1 - 30 250 30 745 kN lt Vnf 770kN VWmax lt 45 0.18MC1 ck 250 ck 0.18 x 350 x 650 1 30 250 30 1081 kN gt VEf 770kN 2. Determine angle 0 From equation 5.8 a or alternatively from...

## Concrete Interaction Diagram

M-N interaction diagram or a non-symmetrical section Non-rectangular M N interaction example EXAMPLE 4.11 M-N interaction diagram for a non-rectangular section Construct the interaction diagram for the equilateral triangular column section in figure 4.23 with i 25N mm2 and gt k 500N mm2. The bending is about an axis parallel to the side AA and causes maximum compression on the corner adjacent to the steel area A'. Non-rectangular M N interaction example

## Pile Cap Truss Analogy

Therefore, substituting for y and .vn P, 166.7 - 35.4 x 1.67 33.3 x 1.0 - 140.9kN P2 166.7 - 35.4 x 1.67 - 33.3 x 1.0 74.3 kN Pi 166.7 35.4 x 0.33 33.3 x 1.0 211.7 kN P4 166.7 35.4 x 0.33 - 33.3 x 1.0 145.1 kN Ps 166.7 35.4 x 1.33 33.3 x 1.0 247.1 kN P6 166.7 35.4 x 1.33 - 33.3 x 1.0 180.5 kN When a pile group is unsymmetrieal about both co-ordinate axes it is necessary to consider the theory of bending about the principal axes which is dealt with in most textbooks on strength of materials. In...

## Design of slender columns

As specified in section 9.2. a column is classified as slender if the slendcmcss ratio about either axis exceeds the value of A itn. If A lt A , then the column may be classified as short and the slenderness effect may be neglected. A slender column with X gt A m must be designed for an additional moment caused by its curvature at ultimate conditions. EC2 identifies four different approaches to designing slender columns 1. A general method based on a non-linear analysis of the structure and...