Week 8 Challenge

Aim : To calculate the centrifugal force for the bridge by using following data.

Given data :

• Width of the carriage way is 7 m
• Span of bridge is 12 m
• Design speed of the more 75 km/hour
• Radius of curvature in the bridge is 3 m
• Bridge is subjected to a live load of class 70 R tracked vehicle

Theory :

The moving of a vehicle in a curve produces an outward pushing force from the bridge which exerts a loads on the structural elements of the bridge is called the centrifugal loads

For calculating water current forces IRC 6:2000 is used.

Calculation:

C = ( W x V² ) / 127 x R

Where , C is centrifugal force

V is the design speed

R is the radius of the curvature

W is the live load

C = ( 70 x 75² ) / 127 x 3

C = 1033.464 KN

Aim : To prepare the model in a STAAD Pro and perform the analysis and justify with the results.

Theory : The general steps to be create a STAAD Pro model is given below,

Step 1 : Create the nodes by using the nodes cursor.

Step 2 : Joining the nodes by using the respective beam plate cursor.

Step 3 : Supports given to the nodes whether its pinned or fixed or any other custom supports

Step 4 : specifications given to the respective beams plates Step 5 : Assign the dead load as per calculation

Step 6 : Save the model and perform the analysis

Step 7 : The results are obtained and discuss with the results Step 8: Take the print out of report of necessary results.

Creating the nodes by using node cursor.

Open the STAAD Pro window > Select > Node cursor > enter the value with respect to X Y Z axis > click enter

Join the nodes by using beam cursor.

Select > beam cursor > join by dragging the mouse or enter the node numbers > click enter

model has been prepared.

Assigning the properties to the beam .

Specification > Prismatic > Rectangle > enter dimensions > select the beam > assign the properties to selected beams.

Supports are given to the respective nodes.

Specifications > Supports > select the supports > click enter

Properties are assigned.

girder properties are assigned.

Defining the load cases .

Definition > Vehicle definition > define load > Add

Loadcase > add > load generation > add

Add > give the ranges > add

Run analysis > go to post processing mode > Results

The reactions are generated at the end of the nodes .the reaction value is 2066.92 KN

• The maximum deflection in X direction is 7.204 mm
• The minimum deflection in X direction is -7.949 mm
• The maximum deflection in Y direction is 0.005 mm
• The minimum deflection in Y direction is -76.961 mm
• The maximum deflection in Z direction is 3.78 mm
• The minimum deflection in Z direction is -4.72mm

• The maximum shear force in X direction is 1260.506 KN
• The minimum shear force in X direction is -33.22 KN
• The maximum shear force in Y direction is 889.566 KN
• The minimum shear force in Y direction is -1082.165 KN
• The maximum shear force in Z direction is 33.713 KN
• The minimum shear force in Z direction is -36.328 KN

• The maximum bending moment in X direction is 185.381 KN-m
• The minimum bending moment in X direction is -184.116 KN-m
• The maximum bending moment in Y direction is 205.405 KN-m
• The minimum bending moment in Y direction is -170.305 KN-m
• The maximum bending moment in Z direction is 1136.796 KN-m
• The minimum bending moment in Z direction is -1184.71 KN-m

The max shear stress in x is 207.107 kilo newton square mm

The min shear stress in x is -143.946 kilo newton square mm

• Reports are taken printout which ever is necessary by using report
• In the report option we obtain the results of section forces, displacement, reactions, plate
• The exact report is to be taken further move to design