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Design Parameters

Concrete Grade 25N/mm2

Concrete Cover 25mm

Density of Concrete 25kN/m3

Strength of Structural steel 275N/mm2

Method of construction Propped

 Imposed Loads

Description Old design Design review

Live load 5kN/m2 5.0 kN/m2

Wall loads 5 kN/m 15.75 kN/m2

Steel sections

PB 350X175 x49.6kg/m

PB1 350X175 x 41.4 kg/m

SB 250x125 x25.7 kg/m

Analysis Models

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Design and Analysis Out put

Cross Girder SB

Deflections old SLS 51 mm

LL 29 mm

Deflectionsreview SLS 64 mm

LL 42 mm

Ultimate Moments Mu old 162 kNm

Mu review 162 kNm

Shear Force Fu old 92 kN

Fu review 92 kN

DescriptionStatus

old reviewBending Strength 0.94 0.94

Shear Strength 0.34 0.34

%Composite

Action 74.10% 74.10%

Strength 179 179

Strength for Full

comp action

100% 100%

196 196

Capacity ratio Full 0.826 0.826

 Design Models

 Main Girder PD

Deflections old SLS 16 mm

LL 9 mm

Deflectionsreview SLS 21 mm

LL 13 mm

Ultimate Moments Mu old 358 kNm

Mu review 358 kNm

Shear Force Fu old 187 kN

Fu review 187 kN

DescriptionStatus

old reviewBending Strength 1.15 1.15

Shear Strength 0.38 0.38

%Composite

Action 21.30% 21.30%

Exist strength 321 321

Strength for Full

comp action

100% 100%

416 416

Capacity ratio Full 0.86 0.86

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 Perimeter Cross Beam

Deflections old SLS 20 mm

LL 11 mm

Deflections

review SLS 55 mm

LL 16 mm

Ultimate Moments Mu old 89 kNm

Mu review 241 kNm

Shear Force Fu old 52 kN

Fu review 141 kN

DescriptionStatus

old review

Bending Strength 0.54 1.41

Shear Strength 0.2 0.53

%CompositeAction 74.10% 74.10%

Strength 171 171

Strength for Full

comp action

100% 100%

181 181

Capacity ratio Full 0.49 1.33

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Conclusion

Girder PB

Provided structural steel sections for main Girders are satisfy for both strength and deflection if full composite

action is being used. But due to lack of shear studs used in the constructions, full composite action is not mobilized,

consequently moment capacity and stiffness of the composite beams reduces. Therefore, provided steel girder fail

under then reduce design ultimate loading. While make the adjustment to the live load to consider the stores of height equivalent to 3m, Girder will not further satisfy. However, for working load, the provided section is satisfied

subjected to plastic moments and large deformations.

Therefore it is recommended to increase the capacity of the section by adding additional section (same size) or

welding additional plate (10mm) to the bottom of flange of the girder. Contractor is asked to submit the method

statement for review.

Cross girder SB

Provided section is marginally satisfy for the given loading. But, full composite action is not mobilized due to lack 

of shear studs. Although relative deflection is satisfy, overall deflection (50mm) is passing the code limit.

Therefore, damages to the underneath partition is expected. Slight modifications is required to satisfy the additional

live loads

 Perimeter Cross Beam

In the design, light weight partitions along the perimeter have been considered, but at the site, solid block work was

used. Therefore perimeter beam is subjected to unexpected additional load and the existing steel structural beam is

not adequate for the purpose. Therefore it is recommended to increase the capacity of the section by adding

additional section (same size) or welding additional plate (10mm) to the bottom of flange of the girder. Contractor is

asked to submit the method statement for review.

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Recommendations

Contractor is asked to submit the method statement about the rectifications to be done. All the rectifications should

be done at the zero imposed loading conditions, as structure is safe without imposed loads. It is recommended to

 jack the beams where higher amount of deflections were detected before doing the rectifications. Following

recommendations will be adopted as possible rectifications methods

Perimeter Cross Girder

Weld 125X10mm steel plate 10mm Thick) along the bottom flange of the Steel Girders SB at the edge of the slabs

and weld stiffeners (5mm thick plates) to the web at the either side of the girders (all the SB Girders) at the interval

of 300mm between first 2m from the supports and rest of the beams at the interval of 600mm

Girder PB

Weld 175X10mm steel plate 10mm Thick) along the bottom flange of the Steel Girders SB at the edge of the slabs

and weld stiffeners (5mm thick plates) to the web at the either side of the girders (all the SB Girders) at the interval

of 300mm between first 2m from the supports and rest of the beams at the interval of 600mm.