Week 10 Challenge

Week 10 Challenge

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Calculate the snow load accumulated in the bridge shown in fig.

• Span of the bridge is 10m. The snow is settled snow.
• The deck of bridge is flat with B <30 degree.
• The depth of accumulation of snow is 1250 mm.

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AIM: Calculate the snow Load on given bridge having span of 10 m with 4 Nos of RCC Girders with spacing of 4 m C/C. Analysis of the bridge with Snow loading with given data through STAAD.Pro

INTRODUCTION:

• Snow loads indicate the amount of additional force pressing down on a building or a bridge when winter storms pile snow and ice on the roof. There are two types of loads in construction: live loads and dead loads. Ever-changing live loads like snow and ice are temporary weights on the structure.
• DATA GIVEN

Span = 1X10 m

No of girders = 4

Spacing of the girders= 4 m C/C

Cantilever portion =3m either side

Height of parapet wall (crash barrier) =1.5 m

Loading = Settle snow

Depth of accumulation = 1250 mm

Bita <30 degrees

• Assumptions (Data is not given)

Main Girder is rectangular 500 mm width and 1200 mm deep.

Cross Girder is rectangular 300 mm width and 700 mm deep.

Thickness of parapet wall is 300 mm.

• PROCEDURE

Ø Create the STAAD Model

Ø Loading

Ø Analysis

Ø Result

• Create the Model in Staad. Pro

1. Create a node, select the node, create another node with spacing of 7m in y-direction with the help translation repeat.

2. Add the Beam with connected the two nodes to form a column of 7 m height,

3. Translate other 3 no of column with spacing of 4 m in Z-direction and connect each other with add beam to make the cross beams (Traverse beams).

4. Translate the another set of 4 columns in the X-direction with the spacing of 10m as give span is 10 m.

5. Connect the columns in X-direction with add beams for create the main beams (longitudinal beam) as shown in the fig-1 below.

Fig-1

6. Assign the properties 1.2 m diameter for the Column as shown in the Fig-2 below with help of command of create property.

Fig-2.

7. Assign the properties 0.5 m wide and 1.2m deep for the main beam as shown in Fig-3 below (after that deep has been changed from 0.9 m to 1.2m).

Fig-3.

8. Assign the properties of 0.3 m wide and 0.7 m deep for cross beam as highlighted in the Fig-4 below.

Fig-4.

9. Create a mess of 0.5 mX0.5m to make plate of 900 mm for slab as shown in the Fig-5 below.

Fig-5

10. Translation repeats to form a mess in both X and Z-directions for entire span between two main beams and two cross beams respectively as shown in the Fig-6

Fig-6

11. In the same way the mess is created amongst all beams as shown in fig-7.

12. And create the mess of 0.5 m X 0.5 m for the Cantilever slab also as highlighted.

Fig-7

13. Transilate the mess for entire slab and cantilever portion as shown in the Fig-7

3D VIEW OF THE MODEL

Snow Load Calculation: -

Density of settled Snow= 3KN/M3

Depth of snow = 1.2 m

Flat deck angle = 0 degrees

Snow Load S0 = 3X1.2X10 =36 KN/m

Shape coeffient from IS 875 Part 4 µ=0.8 (For β<30 deg)

Design snow load (S)=µx So = 0.8X36= 28.8 KN/m.

Minimum Snow load as per IRC=9KN/m²

Apply the load 28.8 KN/m² has applied on the Cross Girder as shown in the Fig-8

Fig-8

Fig-9

Applied 9KN/m² on the deck slab which is minimum snow load as per IRC as show in the Fig-9.

Analysis of structure

No errors and no warnings

RESULTS

Maximum Bending Moment in the Beam= -81.577 KN-m

Maximum SF in the Beam =116 KN

Maximum deflection = 0.57 mm

Maximum Bending Moment in the Colmn=59.04 KN-m

Maximum deflection =-0.104 mm

Maximum Reaction in the Colmn=254 KN

Maximum BM in Slab = 67.1 Kn-m