Week 8 Challenge

The 3D render view of the defined structure.Aim and Introduction:-

• The aim of this challenge is to calculate the centrifugal force on the structure and to calculate the effect on the structure as various forces like shear force, bending moment etc using staad Pro.
• So first of all the details components for calculating the centrifugal load due to different types of class of vehicles is to be determined from the given data.
• Then the model will be created in Staad pro., centrifugal load is applied on the the structure separately and the reactions, stresses and bending moments due to the loading is being analyzed for the structure as given.

Data Given:-

• Span of bridge - 12m
• Width of Bridge - 7m
• The bridge is subjected to a live load - Class 70R tracked vehicle.
• Design speed (V) - 75 km/hr.
• Radius of curvature - 3m
• 

Calculation of the Centrifugal Forces :-

Considering the impact Load

• For tracked vehicles and spans >9m, the impact load as per IRC-6 code is 25% of the live load.

So impact Load = 25% of 70

i.e.= 17.5 KN

Then,

Radius of curvature , R =3m

Live Load , W = (70 + 17.5)KN =87.5 KN

Design Speed , V = 75 Km/hr

Centrifugal Force = (W x V^2)/127 x R

= (87.5 x 75 x 75) / (127 x 3)

= 1292 KN

STAAD Pro. Analysis:-

• The bridge has been created by considering 4 spans of 12 m length and the cross section of the bridge is taken as 7 m carriage way width.

The bridge model has been created by considering the following details.

• Pier - 1.2m x 1.2m
• pier Ht. - 9.0m
• Main girder - 0.75m x 1.2m
• cross girder - 0.75m x 0.75m
• Deck slab (Plate) thickness - 0.30m

Fixed support has been created and has been applied to all the support nodes.

The 3D render view of the defined structure.

Applying the centrifugal load at the mentioned node (co-ordinate) at the two locations as given above.

Addition to this dead load and the load at the side beams supposed to Crash barrier loads has been applied to the beams.

The structure is being analyzed and the result after the analysis.

Results:-

Deflection due to centrifugal and impact load

Deflection due to Dead load of the structure.

Deflection due to crash barrier load on the structure.

The reactions at the bottom of the structure.

Mz due to centrifugal force.

Mz due to Dead Load.

• My

• Fz for Crash barrier load

• Fz for Dead load

• Fz for Centrifugal and impact load

• Fy for Dead load with annotating all the maximum values

• Variation of plate load due to "My" for Dead load

• Variation of plate load due to "My" for CB load

• Variation of plate load due to "My" for Centrifugal load

The plate load stresses for the moving load at various places according to various positions can be carried out.

For details of the results as minimum, maximum at diffrent span positions, reports can be generated for design and detailing of the structure.