Week 1 Challenge

DESIGN AND ANALYSIS OF BOX GIRDER BRIDGE USING STAAD PRO.

AIM

To Analyse and design a box girder bridge using STAAD Pro. Software.

INTRODUCTION

As per the given data to calculate the dead loads of the box girder bridge UNIT WEIGHT OF BUILDING MATERIALS/DEAD LOAD OF BUILDING MATERIALS AS PER IS 875(Part - 1) - 1987 is being considered for finding the dead loads of Deck slab and Box girder.The reference of the IS CODE is as below

PROCEDURE

1. Manual Calculation

1. Dimension and details of Deck slab and Box girder

ii) Self weight of Deck slab = Width x Thickness x Unit weight of concrete

= 2 x 2.27 x 0.225 x 25 (Referred from IS CODE 875 - PART 1 Reference attached above)

Self weight of Deck slab = 25.53 KN

iii) Self weight of Box girder = Area x Unit weight of concrete

Area of box girder = Outer area - Inner area

Outer area = Area of triangle 1 + Area of rectangle + Area of triangle 2

Area of triangle 1 and 2 = 2 x 1/2 x 0.82 x 2.4

= 1.968 sqm

Area of rectangle = 4.02 x 2.4

= 9.648 sqm

Outer area = 1.968 + 9.648

= 11.548 sqm

Inner area = Area of triangle 1 + Area of rectangle + Area of triangle 2

Area of triangle 1 and 2 = 2 x 1/2 x 0.74 x 1.975

= 1.462 sqm

Area of rectangle = 3.642 x 1.975

= 7.192 sqm

Outer area = 1.462 + 7.192

= 8.654 sqm

Total area of box girder = Outer area - Inner area

= 11.548 - 8.654

= 2.89 sqm

Self weight of box girder = Area x unit weight of concrete

= 2.89 x 25

Self weight of Box girder = 72.32 KN

Total self weight of the bridge = Self weight of Deck slab + Self weight of Box girder

= 25.53 + 72.32

TOTAL SELF WEIGHT OF THE BRIDGE = 97.85 KN

1. Design of Box girder bridge in Staad pro.

Step 1 - Create Nodes by entering the corresponding X/Y/Z values in the Node table for Deck slab and box girder design.

Step 2 - After creating the nodes connect those nodes with add beam option.

Step 3 - Then Click specification tab and click pinned support.

Step 4 - After that in create support dialog box add the required support with moment and forces assign to the four bottom corners of the box girder

Step 5 - After adding supports create required nodes in deck slab and box girder after that click Geometry tab and choose Add plates option

Step 6 - Then connect all 4 corners of the node with add plate option

Step 7 - Then in Properties tab click Prismatic and add the required property like Tapered I beam for corner Beams of the deck slab,Rectangular beams for box girder & cross beams,Plate thickness for all the plates in the geometry.

Step 8 - After adding the properties click Loading tab and add a primary load case as DEAD LOAD

Step 9 - Then click the Dead load tab and add the following Dead loads

1. Self Weight Y direction - Applies to the whole geometry
2. Uniformly distributed self weight 97.85 KN as obtained through manual calculation - Applies to corner I beams in Deck slab
3. Super imposed dead load 5 KN/sqm standard for Footway - Applies to corner I beams in Deck slab
4. Finishes Plate load 1.8 KN/sqm for Bitumen layer on the road - Applies to Deck slab

Step 10 - After applying the dead loads in analysis and design tab define commands for PERFORM ANALYSIS and click run analysis.

RESULTS

Axial Force displacement FX

Axial Force - Shear Y displacement FX,FY

Axial Force - Shear Z - Shear Y displacement FX,FY,FZ

Reactions

Max Axial Force

Plate results

REPORT

FINAL THREE DIMENSIONAL MODEL OF BOX GIRDER BRIDGE