Challenge

Week 2 Challenge

MMadhu Surya27 Feb 2022

AIM & INTRODUCTION:

To design the I Girder Bridge and Apply the IRC live loads and model in Staad pro and perform the structural analysis.

Live Load;

The live load on the bridge, is moving load on the bridge throughout its length. The moving loads are vehicles, Pedestrians etc. but it is difficult to select one vehicle or a group of vehicles to design a safe bridge.

Why is important to calculate live loads in bridge?

These loads acting on the bridges and increase the dead and self-weight of the bridges. It can be assumed by the designer because they live load is one of the major loads in structural design.

GIVEN DATA:

Width of the bridge deck is 7m
Span of the bridge is 24m
Pier size is 2 m diameter
The seismic zone is Zone III
Wind speed is 42 km/hr
Unit weight of soil is 18 kN/m3.

PROCEDURE:

Since the height of the pier is not mentioned I have assumed the height of the pier as 12m. in XY coordinates. To do so in STAAD Pro we have to go to the Geometry option and gives length of nodes in XY direction and select the two nodes using add beam cursor and connect the two nodes and the pier is created.

In the given question they have assigned the diameter of the Pier as 2m. To describe that in STAAD Pro go to the Specification option and go to Prismatic menu and select circle and give the 2m diameter using Concrete material and select the beam and click assign to selected beams and assign and click YES . The pier is created with a diameter of 2m and height of 12m.

To crete another pier for a width of 7m in STAAD Pro click ctrl C and ctrl V , a box will appear. We should assign values as X=0;Y=0;Z=7m and click OK . We shall have created another pier with a width of 7m in the Z direction.

After creating the piers go to Geometry option and click Add beam and connect the upper side of the two piers. After connecting the beam , select the beam and go to the define option in user table and go to the rectange option and give values of YD=0.6m;ZD=1.2m using Concrete material and select the beam and click assign to selected beams and assign and click YES. We shall have created the crossbeams .

After that select all the beams using beam cursor and click ctrl C and ctrl V , a box will appear. We should assign values as X=24m;Y=0;Z=0 and click OK. We will have created the mirror image of the beams at a distance of 24m.

Now go the Geometry Option and select the Add Beam option and conned the upper nodes horizontally on both sides. .

We should create the supports for the piers. To do that we should go to the select node cursor option and select all the nodes at the bottom of the four piersand go to Specification Option and select Fixed option and click Add and select the support 1 option and click assign to selected beams and assign and click YES. We shall have created all the fixed supports at the pier.

In the given question we should create girder along the X direction . To do so select the node cursor and select the first pier on th beam and go to Geometry option and go to Translational Repeat in Z direction and assign the No. of Steps=1;Default Step Spacing=0.65m. Continue the same on the other side of the pier and by using the Add beam cursor Join the the two nodes.

Again the select the node by using node cursor option at the 0.65m node and go to Geometry option and select Translational Repeat in Z direction and assign the No. of Steps=1;Default Step Spacing=1.9m.Repeat the same process on the other side of the beam and connect the beams using add beam option.

Again the select the node by using node cursor option at the 1.9m node and go to Geometry option and select Translational Repeat in Z direction and assign the No. of Steps=1;Default Step Spacing=1.9m.Repeat the same process on the other side of the beam and connect the beams using add beam option.

Select the node cursor and select the first pier on th beam and go to Geometry option and go to Translational Repeat in X direction and assign the No. of Steps=1;Default Step Spacing=8m. Continue the same on the other side of the pier and by using the Add beam cursor Join the the two nodes.

Select the node cursor at 8m and go to Geometry option and go to Translational Repeat in Z direction and assign the No. of Steps=1;Default Step Spacing=8m. Continue the same on the other side of the pier and by using the Add beam cursor Join the the two nodes. Now we haved created all the girders and cross girders.

To assign the beams go to the user data and select define option. In that select the rectangle section of YD=0.55m;ZD=0.2m along both the X axis. After that select the Beams and assign to selected beams and assign. Then click Yes.

Now select all the GIRDERS and go to user data and select define . in the screen select the rectyangale section and add the values of YD=1.7m;ZD=0.5m using Concrete material. After that select the Beams and assign to selected beams and assign. Then click Yes.

Then select all the cross Girders and go to user data and select define . in the screen select the rectyangale section and add the values of YD=1.5m;ZD=0.3m using Concrete material. After that select the Beams and assign to selected beams and assign. Then click Yes.

Select the node cursor and select the first pier on th beam and go to Geometry option and go to Translational Repeat in Z direction and assign the No. of Steps=1;Default Step Spacing=0.5m. Again Select the node cursor and select the first pier on th beam and go to Geometry option and go to Translational Repeat in X direction and assign the No. of Steps=1;Default Step Spacing=0.5m. A box will be made using the plate beam and a plate is applies using the plate cursor. Select the plate and go to Geometry option and go to Translational Repeat in X direction and assign the No. of Steps=47;Default Step Spacing=0.5m. Now copy all the plates and go to Geometry option and go to Translational Repeat in Z direction and assign the No. of Steps=13;Default Step Spacing=0.5m. We will have created all the plates.

To assign values for the plates go for the Specifications Options and select the Plate Thickness and give values as Node 1=0.2m;Node 2=0.2m;Node 3=0.2m;Node 4=0.2m. using Concrete material. After that select the Beams and assign to selected beams and assign. Then click Yes.

After assigning the values to be the beams we should name the Group in order to specifiy the beams. To name the group ctrl G and Group Box and name the Group as BEAMS and the Type as Beams and click OK. Associate the Beams and highlight the Beams.

Create the group name as GIRDER and the Type as Beams and click OK. Associate the girder and highlight the gieder.

Create the group name as CROSS GIRDER and the Type as Beams and click OK. Associate the Cross girder and highlight it. Create the group name as PIER and the Type as Beams and click OK. Associate the pier and highlight it.

RESULT:

To obtain results we need assign the live loads to the structure. In order to do so we should go to the Loading menu and go to Definition and select Vehicle Definition. Click add and define load. Mention the width as 1.6 . Add the Class A loading as mentioned in IRC 6 code. and click Add.

And again go the load definition Option and select Vehicle Definition. Click add and define load. Mention the width as 1.6 . Add the Class 70 R loading as mentioned in IRC 6 code. and click Add.

Select the Load Case Details and click Add and go to load Generation and add the No. of Loads to be Generated as 200 and add. GGoWe should apply the load at the specific point on the slab. To do that go to Load Generation Type and select Initail Portion of Load and give following values as X=-18.8m;Y=12m;Z=0.65m and Load Increment as 0.2 in X Increment. in Class A Loading.

Select the Load Case Details and click Add and go to load Generation and add the No. of Loads to be Generated as 200 and add. We should apply the load at the specific point on the slab. To do that go to Load Generation Type and select Initail Portion of Load and give following values as X=-14.4m;Y=12m;Z=0.65m and Load Increment as 0.2 in X Increment. for Class 70R Loading. After assign the Loads Go to analysis and Design Command and select the Analysis Command and Perform Analysis. Then go to Run analysis and go to the Post Processing Mode. IN the Post Processing Mode we can obtain the Required Results.

REPORT:

We shall be able to observe the moving Live loads in the above mentioned pictures of Class A and Class 70R. To do that go the Results Section and select the View Loading Diagram and apply the moving Live loads.

To obtain the Required results Bending moment, go to the Moment at MZ and select Result option and select the Beam End Forces by selecting all the Beams at Moment at Z and List from Hign to Low.

To obtain the Required results Shaer Force, go to the Moment at FY and select Result option and select the Beam End Forces by selecting all the Beams at Moment at Z and List from Hign to Low and section Forces at Shear Y and List from Hign to Low.

To obtain the Required results Bending moment, Select all the plates and select Result option and select the Plate Stresses by selecting all the Plates.