reliable essay assistance on Post-tensioned beam lab report

Assignment Title:
Post-tensioned beam experiment:
1) Three 100mm concrete cubes will be tested on the day of the experiment. The average of these three cube strengths will be assumed to be the fcu value for the concrete.
2) One standard 300mm cylinder specimen will also be tested on the day, in accordance with BS 1881, to determine the modulus of elasticity of the concrete, Ec. Concrete density can be assumed to be 2400kg/m3.
3) A stress strain curve is provided in this descriptor for the 5mm diameter prestressing wire used. Any calculation involving the modulus of elasticity for the steel, Es, shall use the value derived from this graph.
4) The beam has an overall length of 4m. The cross-sectional dimensions and locations of the wire centrelines are as shown in Figure 1, together with the loading arrangement.

Method:
1) Stressing will be carried out using the normal design data given in the code for 5mm diameter wire.
2) Characteristic strength (fpu) 30.8kN
3) Cross-sectional area (Apu) 19.6mm2
4) The initial (transfer) force per wire, Pi, is to be 0.7 Pu, where Pu is the characteristic strength. Hence, Pi = 21.5kN and the corresponding stress, fpi, is 1100N/mm2.
5) The anchorage device used in the stressing system (PSC Monowire) is subject to a small amount of slip; i.e. loss of extension, when the anchorage is driven home and the jack load reduced to zero. This slip amounts to about 5mm on average and is allowed for.
6) Immediately before the commencement of stressing, and at stages throughout the test, measurements will be taken to determine the distribution of concrete surface strain across the entire depth of the beam. In addition, vertical displacement will be recorded at mid-span.

Loading regime:
The beam element will be loaded in stages until failure occurs.
Results:
1) Basic data
Record the identification number for the beam, dates of casting, stressing and testing.
Concrete elastic modulus, Ec, will be determined from a cylinder test, carried out by two
members of the group. The results are to be reported individually.
2) Initial prestress and eccentricity
These will be determined from the stress calculated from the force applied (allowing for a
30% loss) and the cross sectional area of the wire, and from sectional geometry.
3) Concrete strain distributions
With strain gauge readings taken before stressing as a baseline, determine the strain
distributions over the whole depth of the section:-
i) Immediately after stressing
ii) Immediately before loading
iii) At individual load stages
CL
P
125mm 1250mm 625mm 625mm 1250mm 125mm
75mm 50mm
200mm

Plot each distribution on a single graph. Determine the location of each set of gauge points and then draw strain distribution over the full depth of the section, neglecting any tensile strain readings which may be affected by crack development at loads close to failure.
Provide a critical review on the pattern of distributions with increasing load, making appropriate allowances for possible inaccuracy in readings.
4) Load deflection curve
Plot to as large a scale as possible the load-deflection curve for the loading cycle. The initial stage of the loading cycle will have a linear relationship. Locate the point of the onset of non-linear behaviour.
5) Camber due to prestress
Mid-span deflections measured during stressing will provide evidence of camber.
6) Ultimate moment of resistance
Calculate in accordance with the code:
i) With fcu equal to the mean cube strength
ii) Aps is the cross-sectional area of the wires
Compare the calculated value with Mult under the failure load and self-weight and make comment appropriately.

Presentation of results:
1) A laboratory report containing all pertinent information and suitable critical commentary on all aspects covered above.
Note: For a beam subjected to a constant moment M (i.e. Pe) the central deflection (i.e. camber) is

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