Week 7 Challenge

Aim : To calculate the water current forces for the bridge.

Given data :

• The high flood level is 2 m above foundation level
• Span of bridge is 45 m
• Mean velocity of river is 3m/s

Theory : Water current forces are the forces which is caused due to the ocean currents.

The major ocean currents are is given below

1 North equatorial current

2 Equatorial counter current

3 Atlantic current

4 North specific current

5 South Indian current

For calculating water current forces IRC 78:2000 is used.

Calculation:

Shape factor K = 0.66 . As per IRC 78:2000

Max. Velocity, V = √2 x V_mean

= √2 x 3

Max. Velocity, V = 4.24

Water current, P = 52 x K x V²

= 52 x 0.66 x 4.24²

Water current, P = 560.901 KN/m²

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.And also by using Translation repear command model has been prepared.

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

plate elements are drawn by using nodes and model has been prepared.

properties are defined.

Assigning the properties to the beam .

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

Plates properties are defined and assinged.

Specifications > Supports > select the supports > click enter

Supports are given to the respective nodes.

Defining the load cases .

Loading > Load case detail > select load > Add

Add > member load > Linear varying > enter the value and give the direction > ok

Select the defined load > select the beam > Assign to selected beam > click enter

Run analysis > go to post processing mode > Results

The reactions are generated at the respective nodes .the reaction value is 3366 KN

• The maximum deflection in X direction is 0.002 mm
• The minimum deflection in X direction is -0.002 mm
• The maximum deflection in Y direction is 0.022 mm
• The minimum deflection in Y direction is -0.022 mm
• The maximum deflection in Z direction is 2.457 mm
• The minimum deflection in Z direction is -2.457 mm

• The maximum Shear force in X direction is 5.769 KN
• The minimum Shear force in X direction is -5.769 KN
• The maximum Shear force in Y direction is 5.196 KN
• The minimum Shear force in Y direction is -5.196 KN
• The maximum Shear force in Z direction is 560.986 KN
• The minimum Shear force in Z direction is -560.986 KN

• The maximum Bending moment in X direction is 4.416 KNm
• The minimum Bending moment in X direction is -4.416 KNm
• The maximum Bending momentin Y direction is 351.739 KNm
• The minimum Bending moment in Y direction is -351.739 KNm
• The maximum Bending moment in Z direction is 15.986 KNm
• The minimum Bending moment in Z direction is -15.986 KNm

• 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