Week 1 Challenge

Dead weight of Super structure:

Volume of the section: Area * Length

To calculate the area of the box girder section. I have drawn it in AutoCAD for accuracy.

using Massprop command in AutoCAD, we can get sectional properties of the section as below.

Whole section area from AutoCAD: 13115901.6612 sqmm.

Hollow section area from AutoCAD: 8564011.2342 sqmm.

Net Area of the Box section Girder: 13115901.6612 - 8564011.2342 = 4551890.427/1000000 = 4.552 sqm.

Weight per meter: Area * Density of Concrete

: 4.552 * 25

: 113.8 KN/m.

Consider concrete parapet wall of 1.5m height at both ends of the section and 200mm thick.

weight per meter: Area * Density of Concrete

: 1.5 * 0.2 * 25 * 2Nos.

: 15 KN/m.

Consider 150mm thick floor finish screed on full width of girder.

Weight per meter: 0.15 * 10.2 * 22*

: 33.66 KN/m.

(*Density of screed could vary upon material to be adopted, sometimes density of concrete is also adopted in design.)

Total Dead Weight of super structure per meter could be calculated as: weight of box girder + Parapet + finish screed

: 113.8 + 15 + 33.66

: 162.46 KN/m

Other than the loads mentioned above, load of dividers, side walks, street lights and other utilities could be calculated as details mentioned in architectural drawings or tender drawings.

Dead weight for 12m Span: 162.46 * 12

: 1949.52KN.

To calculate load on Piers, above load is divided in to half and adjacent half span dead load is added.

Dead weight of Sub structure:

Weight of Pier Cap-

Let us assume a trapezoidal Pier cap of width in transverse direction as 4.2m, depth of 1m at Pier face tapering to 0.5m at the free end and width in longitudinal direction as 3m.

Pier Diameter is 2.5m.

Volume of Pier Cap: upper rectangular portion + lower triangular portion on both sides + lower middle rectangular portion

: (4.2 * 3 * 0.5) + (1/2*(4.2 - 2.5) * 3 * 0.5) + (2.5 * 3 * 0.5)

: 6.3 + 1.275 + 3.75

: 11.325 cubicmeter.

Weight of Pier Cap: 11.325 * 25

: 283.125 KN

Weight of Pier-

Let us assume height of Pier below Pier Cap Bottom as 12m

Volume of Pier: 0.785 * 2.5 * 2.5 * 12

: 58.875 cubicmeter.

Weight of Pier: 58.875 * 25

: 1471.875 KN

Other than Pier cap, Pier, weight of Bearing pedestals, seismic restrainers also could be calculated as per design requirement.